X-Git-Url: https://git.auder.net/?a=blobdiff_plain;f=base_rules.js;h=beac0bb020a361c7742d4f4d17a270380d7c57cd;hb=f31de5e46015a93dca20765da61670035ce8f491;hp=8ad0894e2972c074d8474844e15d52511fefc7d8;hpb=3b641716d7e86d9f1b39d1e046ce197e6b5a8075;p=xogo.git

diff --git a/base_rules.js b/base_rules.js
index 8ad0894..beac0bb 100644
--- a/base_rules.js
+++ b/base_rules.js
@@ -3,6 +3,21 @@ import { ArrayFun } from "/utils/array.js";
 import PiPo from "/utils/PiPo.js";
 import Move from "/utils/Move.js";
 
+// Helper class for move animation
+class TargetObj {
+
+  constructor(callOnComplete) {
+    this.value = 0;
+    this.target = 0;
+    this.callOnComplete = callOnComplete;
+  }
+  increment() {
+    if (++this.value == this.target)
+      this.callOnComplete();
+  }
+
+};
+
 // NOTE: x coords: top to bottom (white perspective); y: left to right
 // NOTE: ChessRules is aliased as window.C, and variants as window.V
 export default class ChessRules {
@@ -96,6 +111,11 @@ export default class ChessRules {
     return !!this.options["dark"];
   }
 
+  // Some variants use only click information
+  get clickOnly() {
+    return false;
+  }
+
   // Some variants use click infos:
   doClick(coords) {
     if (typeof coords.x != "number")
@@ -110,7 +130,7 @@ export default class ChessRules {
           new PiPo({
             x: coords.x,
             y: coords.y,
-            c: this.captured.c, //this.turn,
+            c: this.captured.c,
             p: this.captured.p
           })
         ],
@@ -177,8 +197,19 @@ export default class ChessRules {
     return (f.charCodeAt(0) <= 90 ? "w" + f.toLowerCase() : "b" + f);
   }
 
-  // Setup the initial random-or-not (asymmetric-or-not) position
   genRandInitFen(seed) {
+    Random.setSeed(seed); //may be unused
+    let baseFen = this.genRandInitBaseFen();
+    baseFen.o = Object.assign({init: true}, baseFen.o);
+    const parts = this.getPartFen(baseFen.o);
+    return (
+      baseFen.fen +
+      (Object.keys(parts).length > 0 ? (" " + JSON.stringify(parts)) : "")
+    );
+  }
+
+  // Setup the initial random-or-not (asymmetric-or-not) position
+  genRandInitBaseFen() {
     let fen, flags = "0707";
     if (!this.options.randomness)
       // Deterministic:
@@ -186,7 +217,6 @@ export default class ChessRules {
 
     else {
       // Randomize
-      Random.setSeed(seed);
       let pieces = {w: new Array(8), b: new Array(8)};
       flags = "";
       // Shuffle pieces on first (and last rank if randomness == 2)
@@ -196,9 +226,7 @@ export default class ChessRules {
           flags += flags;
           break;
         }
-
         let positions = ArrayFun.range(8);
-
         // Get random squares for bishops
         let randIndex = 2 * Random.randInt(4);
         const bishop1Pos = positions[randIndex];
@@ -208,7 +236,6 @@ export default class ChessRules {
         // Remove chosen squares
         positions.splice(Math.max(randIndex, randIndex_tmp), 1);
         positions.splice(Math.min(randIndex, randIndex_tmp), 1);
-
         // Get random squares for knights
         randIndex = Random.randInt(6);
         const knight1Pos = positions[randIndex];
@@ -216,18 +243,15 @@ export default class ChessRules {
         randIndex = Random.randInt(5);
         const knight2Pos = positions[randIndex];
         positions.splice(randIndex, 1);
-
         // Get random square for queen
         randIndex = Random.randInt(4);
         const queenPos = positions[randIndex];
         positions.splice(randIndex, 1);
-
         // Rooks and king positions are now fixed,
         // because of the ordering rook-king-rook
         const rook1Pos = positions[0];
         const kingPos = positions[1];
         const rook2Pos = positions[2];
-
         // Finally put the shuffled pieces in the board array
         pieces[c][rook1Pos] = "r";
         pieces[c][knight1Pos] = "n";
@@ -246,19 +270,7 @@ export default class ChessRules {
         " w 0"
       );
     }
-    // Add turn + flags + enpassant (+ reserve)
-    let parts = [];
-    if (this.hasFlags)
-      parts.push(`"flags":"${flags}"`);
-    if (this.hasEnpassant)
-      parts.push('"enpassant":"-"');
-    if (this.hasReserve)
-      parts.push('"reserve":"000000000000"');
-    if (this.options["crazyhouse"])
-      parts.push('"ispawn":"-"');
-    if (parts.length >= 1)
-      fen += " {" + parts.join(",") + "}";
-    return fen;
+    return { fen: fen, o: {flags: flags} };
   }
 
   // "Parse" FEN: just return untransformed string data
@@ -276,23 +288,28 @@ export default class ChessRules {
 
   // Return current fen (game state)
   getFen() {
-    let fen = (
-      this.getPosition() + " " +
-      this.getTurnFen() + " " +
-      this.movesCount
+    const parts = this.getPartFen({});
+    return (
+      this.getBaseFen() +
+      (Object.keys(parts).length > 0 ? (" " + JSON.stringify(parts)) : "")
     );
-    let parts = [];
+  }
+
+  getBaseFen() {
+    return this.getPosition() + " " + this.turn + " " + this.movesCount;
+  }
+
+  getPartFen(o) {
+    let parts = {};
     if (this.hasFlags)
-      parts.push(`"flags":"${this.getFlagsFen()}"`);
+      parts["flags"] = o.init ? o.flags : this.getFlagsFen();
     if (this.hasEnpassant)
-      parts.push(`"enpassant":"${this.getEnpassantFen()}"`);
+      parts["enpassant"] = o.init ? "-" : this.getEnpassantFen();
     if (this.hasReserveFen)
-      parts.push(`"reserve":"${this.getReserveFen()}"`);
+      parts["reserve"] = this.getReserveFen(o);
     if (this.options["crazyhouse"])
-      parts.push(`"ispawn":"${this.getIspawnFen()}"`);
-    if (parts.length >= 1)
-      fen += " {" + parts.join(",") + "}";
-    return fen;
+      parts["ispawn"] = this.getIspawnFen(o);
+    return parts;
   }
 
   static FenEmptySquares(count) {
@@ -333,10 +350,6 @@ export default class ChessRules {
     return position;
   }
 
-  getTurnFen() {
-    return this.turn;
-  }
-
   // Flags part of the FEN string
   getFlagsFen() {
     return ["w", "b"].map(c => {
@@ -347,17 +360,22 @@ export default class ChessRules {
   // Enpassant part of the FEN string
   getEnpassantFen() {
     if (!this.epSquare)
-      return "-"; //no en-passant
+      return "-";
     return C.CoordsToSquare(this.epSquare);
   }
 
-  getReserveFen() {
+  getReserveFen(o) {
+    if (o.init)
+      return "000000000000";
     return (
       ["w","b"].map(c => Object.values(this.reserve[c]).join("")).join("")
     );
   }
 
-  getIspawnFen() {
+  getIspawnFen(o) {
+    if (o.init)
+      // NOTE: cannot merge because this.ispawn doesn't exist yet
+      return "-";
     const squares = Object.keys(this.ispawn);
     if (squares.length == 0)
       return "-";
@@ -385,21 +403,27 @@ export default class ChessRules {
     if (o.genFenOnly)
       // This object will be used only for initial FEN generation
       return;
+
+    // Some variables
     this.playerColor = o.color;
     this.afterPlay = o.afterPlay; //trigger some actions after playing a move
+    this.containerId = o.element;
+    this.isDiagram = o.diagram;
+    this.marks = o.marks;
 
-    // Fen string fully describes the game state
+    // Initializations
     if (!o.fen)
       o.fen = this.genRandInitFen(o.seed);
-    const fenParsed = this.parseFen(o.fen);
-    this.board = this.getBoard(fenParsed.position);
+    this.re_initFromFen(o.fen);
+    this.graphicalInit();
+  }
+
+  re_initFromFen(fen, oldBoard) {
+    const fenParsed = this.parseFen(fen);
+    this.board = oldBoard || this.getBoard(fenParsed.position);
     this.turn = fenParsed.turn;
     this.movesCount = parseInt(fenParsed.movesCount, 10);
     this.setOtherVariables(fenParsed);
-
-    // Graphical (can use variables defined above)
-    this.containerId = o.element;
-    this.graphicalInit();
   }
 
   // Turn position fen into double array ["wb","wp","bk",...]
@@ -429,11 +453,10 @@ export default class ChessRules {
       this.setFlags(fenParsed.flags);
     if (this.hasEnpassant)
       this.epSquare = this.getEpSquare(fenParsed.enpassant);
-    if (this.hasReserve)
+    if (this.hasReserve && !this.isDiagram)
       this.initReserves(fenParsed.reserve);
     if (this.options["crazyhouse"])
       this.initIspawn(fenParsed.ispawn);
-    this.subTurn = 1; //may be unused
     if (this.options["teleport"]) {
       this.subTurnTeleport = 1;
       this.captured = null;
@@ -443,48 +466,14 @@ export default class ChessRules {
       this.enlightened = ArrayFun.init(this.size.x, this.size.y, false);
       this.updateEnlightened();
     }
+    this.subTurn = 1; //may be unused
+    if (!this.moveStack) //avoid resetting (unwanted)
+      this.moveStack = [];
   }
 
-  updateEnlightened() {
-    this.oldEnlightened = this.enlightened;
-    this.enlightened = ArrayFun.init(this.size.x, this.size.y, false);
-    // Add pieces positions + all squares reachable by moves (includes Zen):
-    for (let x=0; x<this.size.x; x++) {
-      for (let y=0; y<this.size.y; y++) {
-        if (this.board[x][y] != "" && this.getColor(x, y) == this.playerColor)
-        {
-          this.enlightened[x][y] = true;
-          this.getPotentialMovesFrom([x, y]).forEach(m => {
-            this.enlightened[m.end.x][m.end.y] = true;
-          });
-        }
-      }
-    }
-    if (this.epSquare)
-      this.enlightEnpassant();
-  }
-
-  // Include square of the en-passant capturing square:
-  enlightEnpassant() {
-    // NOTE: shortcut, pawn has only one attack type, doesn't depend on square
-    const steps = this.pieces(this.playerColor)["p"].attack[0].steps;
-    for (let step of steps) {
-      const x = this.epSquare.x - step[0],
-            y = this.getY(this.epSquare.y - step[1]);
-      if (
-        this.onBoard(x, y) &&
-        this.getColor(x, y) == this.playerColor &&
-        this.getPieceType(x, y) == "p"
-      ) {
-        this.enlightened[x][this.epSquare.y] = true;
-        break;
-      }
-    }
-  }
-
-  // ordering as in pieces() p,r,n,b,q,k (+ count in base 30 if needed)
+  // ordering as in pieces() p,r,n,b,q,k
   initReserves(reserveStr) {
-    const counts = reserveStr.split("").map(c => parseInt(c, 30));
+    const counts = reserveStr.split("").map(c => parseInt(c, 36));
     this.reserve = { w: {}, b: {} };
     const pieceName = ['p', 'r', 'n', 'b', 'q', 'k'];
     const L = pieceName.length;
@@ -503,6 +492,22 @@ export default class ChessRules {
       this.ispawn = {};
   }
 
+  ////////////////
+  // VISUAL UTILS
+
+  getPieceWidth(rwidth) {
+    return (rwidth / this.size.y);
+  }
+
+  getReserveSquareSize(rwidth, nbR) {
+    const sqSize = this.getPieceWidth(rwidth);
+    return Math.min(sqSize, rwidth / nbR);
+  }
+
+  getReserveNumId(color, piece) {
+    return `${this.containerId}|rnum-${color}${piece}`;
+  }
+
   getNbReservePieces(color) {
     return (
       Object.values(this.reserve[color]).reduce(
@@ -518,22 +523,6 @@ export default class ChessRules {
       (oldV,newV) => oldV + (this.reserve[c][newV] > 0 ? 1 : 0), 0);
   }
 
-  //////////////
-  // VISUAL PART
-
-  getPieceWidth(rwidth) {
-    return (rwidth / this.size.y);
-  }
-
-  getReserveSquareSize(rwidth, nbR) {
-    const sqSize = this.getPieceWidth(rwidth);
-    return Math.min(sqSize, rwidth / nbR);
-  }
-
-  getReserveNumId(color, piece) {
-    return `${this.containerId}|rnum-${color}${piece}`;
-  }
-
   static AddClass_es(piece, class_es) {
     if (!Array.isArray(class_es))
       class_es = [class_es];
@@ -550,49 +539,70 @@ export default class ChessRules {
     });
   }
 
+  // Generally light square bottom-right
+  getSquareColorClass(x, y) {
+    return ((x+y) % 2 == 0 ? "light-square": "dark-square");
+  }
+
+  getMaxDistance(r) {
+    // Works for all rectangular boards:
+    return Math.sqrt(r.width ** 2 + r.height ** 2);
+  }
+
+  getDomPiece(x, y) {
+    return (typeof x == "string" ? this.r_pieces : this.g_pieces)[x][y];
+  }
+
+  //////////////////
+  // VISUAL METHODS
+
   graphicalInit() {
-    // NOTE: not window.onresize = this.re_drawBoardElts because scope (this)
-    window.onresize = () => this.re_drawBoardElements();
-    this.re_drawBoardElements();
-    this.initMouseEvents();
-    const chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
+    const g_init = () => {
+      this.re_drawBoardElements();
+      if (!this.isDiagram && !this.mouseListeners && !this.touchListeners)
+        this.initMouseEvents();
+    };
+    let container = document.getElementById(this.containerId);
+    this.windowResizeObs = new ResizeObserver(g_init);
+    this.windowResizeObs.observe(container);
   }
 
   re_drawBoardElements() {
     const board = this.getSvgChessboard();
     const oppCol = C.GetOppCol(this.playerColor);
-    let chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
+    const container = document.getElementById(this.containerId);
+    const rc = container.getBoundingClientRect();
+    let chessboard = container.querySelector(".chessboard");
     chessboard.innerHTML = "";
     chessboard.insertAdjacentHTML('beforeend', board);
     // Compare window ratio width / height to aspectRatio:
-    const windowRatio = window.innerWidth / window.innerHeight;
+    const windowRatio = rc.width / rc.height;
     let cbWidth, cbHeight;
-    if (windowRatio <= this.size.ratio) {
+    const vRatio = this.size.ratio || 1;
+    if (windowRatio <= vRatio) {
       // Limiting dimension is width:
-      cbWidth = Math.min(window.innerWidth, 767);
-      cbHeight = cbWidth / this.size.ratio;
+      cbWidth = Math.min(rc.width, 767);
+      cbHeight = cbWidth / vRatio;
     }
     else {
       // Limiting dimension is height:
-      cbHeight = Math.min(window.innerHeight, 767);
-      cbWidth = cbHeight * this.size.ratio;
+      cbHeight = Math.min(rc.height, 767);
+      cbWidth = cbHeight * vRatio;
     }
-    if (this.hasReserve) {
+    if (this.hasReserve && !this.isDiagram) {
       const sqSize = cbWidth / this.size.y;
       // NOTE: allocate space for reserves (up/down) even if they are empty
       // Cannot use getReserveSquareSize() here, but sqSize is an upper bound.
-      if ((window.innerHeight - cbHeight) / 2 < sqSize + 5) {
-        cbHeight = window.innerHeight - 2 * (sqSize + 5);
-        cbWidth = cbHeight * this.size.ratio;
+      if ((rc.height - cbHeight) / 2 < sqSize + 5) {
+        cbHeight = rc.height - 2 * (sqSize + 5);
+        cbWidth = cbHeight * vRatio;
       }
     }
     chessboard.style.width = cbWidth + "px";
     chessboard.style.height = cbHeight + "px";
     // Center chessboard:
-    const spaceLeft = (window.innerWidth - cbWidth) / 2,
-          spaceTop = (window.innerHeight - cbHeight) / 2;
+    const spaceLeft = (rc.width - cbWidth) / 2,
+          spaceTop = (rc.height - cbHeight) / 2;
     chessboard.style.left = spaceLeft + "px";
     chessboard.style.top = spaceTop + "px";
     // Give sizes instead of recomputing them,
@@ -610,7 +620,7 @@ export default class ChessRules {
     const flipped = (this.playerColor == 'b');
     let board = `
       <svg
-        viewBox="0 0 80 80"
+        viewBox="0 0 ${10*this.size.y} ${10*this.size.x}"
         class="chessboard_SVG">`;
     for (let i=0; i < this.size.x; i++) {
       for (let j=0; j < this.size.y; j++) {
@@ -635,51 +645,63 @@ export default class ChessRules {
     return board;
   }
 
-  // Generally light square bottom-right
-  getSquareColorClass(x, y) {
-    return ((x+y) % 2 == 0 ? "light-square": "dark-square");
-  }
-
   setupPieces(r) {
-    if (this.g_pieces) {
-      // Refreshing: delete old pieces first
-      for (let i=0; i<this.size.x; i++) {
-        for (let j=0; j<this.size.y; j++) {
-          if (this.g_pieces[i][j]) {
-            this.g_pieces[i][j].remove();
-            this.g_pieces[i][j] = null;
-          }
-        }
-      }
-    }
-    else
-      this.g_pieces = ArrayFun.init(this.size.x, this.size.y, null);
     let chessboard =
       document.getElementById(this.containerId).querySelector(".chessboard");
     if (!r)
       r = chessboard.getBoundingClientRect();
     const pieceWidth = this.getPieceWidth(r.width);
+    const addPiece = (i, j, arrName, classes) => {
+      this[arrName][i][j] = document.createElement("piece");
+      C.AddClass_es(this[arrName][i][j], classes);
+      this[arrName][i][j].style.width = pieceWidth + "px";
+      this[arrName][i][j].style.height = pieceWidth + "px";
+      let [ip, jp] = this.getPixelPosition(i, j, r);
+      // Translate coordinates to use chessboard as reference:
+      this[arrName][i][j].style.transform =
+        `translate(${ip - r.x}px,${jp - r.y}px)`;
+      chessboard.appendChild(this[arrName][i][j]);
+    };
+    const conditionalReset = (arrName) => {
+      if (this[arrName]) {
+        // Refreshing: delete old pieces first. This isn't necessary,
+        // but simpler (this method isn't called many times)
+        for (let i=0; i<this.size.x; i++) {
+          for (let j=0; j<this.size.y; j++) {
+            if (this[arrName][i][j]) {
+              this[arrName][i][j].remove();
+              this[arrName][i][j] = null;
+            }
+          }
+        }
+      }
+      else
+        this[arrName] = ArrayFun.init(this.size.x, this.size.y, null);
+      if (arrName == "d_pieces")
+        this.marks.forEach(([i, j]) => addPiece(i, j, arrName, "mark"));
+    };
+    if (this.marks)
+      conditionalReset("d_pieces");
+    conditionalReset("g_pieces");
     for (let i=0; i < this.size.x; i++) {
       for (let j=0; j < this.size.y; j++) {
         if (this.board[i][j] != "") {
           const color = this.getColor(i, j);
           const piece = this.getPiece(i, j);
-          this.g_pieces[i][j] = document.createElement("piece");
-          C.AddClass_es(this.g_pieces[i][j], this.pieces()[piece]["class"]);
+          addPiece(i, j, "g_pieces", this.pieces(color, i, j)[piece]["class"]);
           this.g_pieces[i][j].classList.add(C.GetColorClass(color));
-          this.g_pieces[i][j].style.width = pieceWidth + "px";
-          this.g_pieces[i][j].style.height = pieceWidth + "px";
-          let [ip, jp] = this.getPixelPosition(i, j, r);
-          // Translate coordinates to use chessboard as reference:
-          this.g_pieces[i][j].style.transform =
-            `translate(${ip - r.x}px,${jp - r.y}px)`;
           if (this.enlightened && !this.enlightened[i][j])
             this.g_pieces[i][j].classList.add("hidden");
-          chessboard.appendChild(this.g_pieces[i][j]);
+        }
+        if (this.marks && this.d_pieces[i][j]) {
+          let classes = ["mark"];
+          if (this.board[i][j] != "")
+            classes.push("transparent");
+          addPiece(i, j, "d_pieces", classes);
         }
       }
     }
-    if (this.hasReserve)
+    if (this.hasReserve && !this.isDiagram)
       this.re_drawReserve(['w', 'b'], r);
   }
 
@@ -733,7 +755,7 @@ export default class ChessRules {
         r_cell.style.height = sqResSize + "px";
         rcontainer.appendChild(r_cell);
         let piece = document.createElement("piece");
-        C.AddClass_es(piece, this.pieces()[p]["class"]);
+        C.AddClass_es(piece, this.pieces(c, c, p)[p]["class"]);
         piece.classList.add(C.GetColorClass(c));
         piece.style.width = "100%";
         piece.style.height = "100%";
@@ -766,51 +788,29 @@ export default class ChessRules {
     }
   }
 
-  // Apply diff this.enlightened --> oldEnlightened on board
-  graphUpdateEnlightened() {
-    let chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
-    const r = chessboard.getBoundingClientRect();
-    const pieceWidth = this.getPieceWidth(r.width);
-    for (let x=0; x<this.size.x; x++) {
-      for (let y=0; y<this.size.y; y++) {
-        if (!this.enlightened[x][y] && this.oldEnlightened[x][y]) {
-          let elt = document.getElementById(this.coordsToId({x: x, y: y}));
-          elt.classList.add("in-shadow");
-          if (this.g_pieces[x][y])
-            this.g_pieces[x][y].classList.add("hidden");
-        }
-        else if (this.enlightened[x][y] && !this.oldEnlightened[x][y]) {
-          let elt = document.getElementById(this.coordsToId({x: x, y: y}));
-          elt.classList.remove("in-shadow");
-          if (this.g_pieces[x][y])
-            this.g_pieces[x][y].classList.remove("hidden");
-        }
-      }
-    }
-  }
-
   // Resize board: no need to destroy/recreate pieces
   rescale(mode) {
-    let chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
-    const r = chessboard.getBoundingClientRect();
+    const container = document.getElementById(this.containerId);
+    let chessboard = container.querySelector(".chessboard");
+    const rc = container.getBoundingClientRect(),
+          r = chessboard.getBoundingClientRect();
     const multFact = (mode == "up" ? 1.05 : 0.95);
     let [newWidth, newHeight] = [multFact * r.width, multFact * r.height];
     // Stay in window:
-    if (newWidth > window.innerWidth) {
-      newWidth = window.innerWidth;
-      newHeight = newWidth / this.size.ratio;
+    const vRatio = this.size.ratio || 1;
+    if (newWidth > rc.width) {
+      newWidth = rc.width;
+      newHeight = newWidth / vRatio;
     }
-    if (newHeight > window.innerHeight) {
-      newHeight = window.innerHeight;
-      newWidth = newHeight * this.size.ratio;
+    if (newHeight > rc.height) {
+      newHeight = rc.height;
+      newWidth = newHeight * vRatio;
     }
     chessboard.style.width = newWidth + "px";
     chessboard.style.height = newHeight + "px";
-    const newX = (window.innerWidth - newWidth) / 2;
+    const newX = (rc.width - newWidth) / 2;
     chessboard.style.left = newX + "px";
-    const newY = (window.innerHeight - newHeight) / 2;
+    const newY = (rc.height - newHeight) / 2;
     chessboard.style.top = newY + "px";
     const newR = {x: newX, y: newY, width: newWidth, height: newHeight};
     const pieceWidth = this.getPieceWidth(newWidth);
@@ -927,8 +927,8 @@ export default class ChessRules {
       if (cd) {
         const move = this.doClick(cd);
         if (move)
-          this.playPlusVisual(move);
-        else {
+          this.buildMoveStack(move, r);
+        else if (!this.clickOnly) {
           const [x, y] = Object.values(cd);
           if (typeof x != "number")
             startPiece = this.r_pieces[x][y];
@@ -981,32 +981,63 @@ export default class ChessRules {
         if (moves.length >= 2)
           this.showChoices(moves, r);
         else if (moves.length == 1)
-          this.playPlusVisual(moves[0], r);
+          this.buildMoveStack(moves[0], r);
       }
       curPiece.remove();
     };
 
+    const resize = (e) => this.rescale(e.deltaY < 0 ? "up" : "down");
+
     if ('onmousedown' in window) {
-      document.addEventListener("mousedown", mousedown);
-      document.addEventListener("mousemove", mousemove);
-      document.addEventListener("mouseup", mouseup);
-      document.addEventListener("wheel",
-        (e) => this.rescale(e.deltaY < 0 ? "up" : "down"));
+      this.mouseListeners = [
+        {type: "mousedown", listener: mousedown},
+        {type: "mousemove", listener: mousemove},
+        {type: "mouseup", listener: mouseup},
+        {type: "wheel", listener: resize}
+      ];
+      this.mouseListeners.forEach(ml => {
+        document.addEventListener(ml.type, ml.listener);
+      });
     }
     if ('ontouchstart' in window) {
-      // https://stackoverflow.com/a/42509310/12660887
-      document.addEventListener("touchstart", mousedown, {passive: false});
-      document.addEventListener("touchmove", mousemove, {passive: false});
-      document.addEventListener("touchend", mouseup, {passive: false});
+      this.touchListeners = [
+        {type: "touchstart", listener: mousedown},
+        {type: "touchmove", listener: mousemove},
+        {type: "touchend", listener: mouseup}
+      ];
+      this.touchListeners.forEach(tl => {
+        // https://stackoverflow.com/a/42509310/12660887
+        document.addEventListener(tl.type, tl.listener, {passive: false});
+      });
     }
     // TODO: onpointerdown/move/up ? See reveal.js /controllers/touch.js
   }
 
+  removeListeners() {
+    let container = document.getElementById(this.containerId);
+    this.windowResizeObs.unobserve(container);
+    if (this.isDiagram)
+      return; //no listeners in this case
+    if ('onmousedown' in window) {
+      this.mouseListeners.forEach(ml => {
+        document.removeEventListener(ml.type, ml.listener);
+      });
+    }
+    if ('ontouchstart' in window) {
+      this.touchListeners.forEach(tl => {
+        // https://stackoverflow.com/a/42509310/12660887
+        document.removeEventListener(tl.type, tl.listener);
+      });
+    }
+  }
+
   showChoices(moves, r) {
     let container = document.getElementById(this.containerId);
     let chessboard = container.querySelector(".chessboard");
     let choices = document.createElement("div");
     choices.id = "choices";
+    if (!r)
+      r = chessboard.getBoundingClientRect();
     choices.style.width = r.width + "px";
     choices.style.height = r.height + "px";
     choices.style.left = r.x + "px";
@@ -1020,7 +1051,7 @@ export default class ChessRules {
     const callback = (m) => {
       chessboard.style.opacity = "1";
       container.removeChild(choices);
-      this.playPlusVisual(m, r);
+      this.buildMoveStack(m, r);
     }
     for (let i=0; i < moves.length; i++) {
       let choice = document.createElement("div");
@@ -1033,7 +1064,8 @@ export default class ChessRules {
       choice.onclick = () => callback(moves[i]);
       const piece = document.createElement("piece");
       const cdisp = moves[i].choice || moves[i].appear[0].p;
-      C.AddClass_es(piece, this.pieces()[cdisp]["class"]);
+      C.AddClass_es(piece,
+        this.pieces(color, moves[i].end.x, moves[i].end.y)[cdisp]["class"]);
       piece.classList.add(C.GetColorClass(color));
       piece.style.width = "100%";
       piece.style.height = "100%";
@@ -1042,43 +1074,116 @@ export default class ChessRules {
     }
   }
 
-  //////////////
-  // BASIC UTILS
-
-  get size() {
-    return {
-      x: 8,
-      y: 8,
-      ratio: 1 //for rectangular board = y / x
-    };
-  }
+  ////////////////
+  // DARK METHODS
 
-  // Color of thing on square (i,j). 'undefined' if square is empty
-  getColor(i, j) {
-    if (typeof i == "string")
-      return i; //reserves
-    return this.board[i][j].charAt(0);
+  updateEnlightened() {
+    this.oldEnlightened = this.enlightened;
+    this.enlightened = ArrayFun.init(this.size.x, this.size.y, false);
+    // Add pieces positions + all squares reachable by moves (includes Zen):
+    for (let x=0; x<this.size.x; x++) {
+      for (let y=0; y<this.size.y; y++) {
+        if (this.board[x][y] != "" && this.getColor(x, y) == this.playerColor)
+        {
+          this.enlightened[x][y] = true;
+          this.getPotentialMovesFrom([x, y]).forEach(m => {
+            this.enlightened[m.end.x][m.end.y] = true;
+          });
+        }
+      }
+    }
+    if (this.epSquare)
+      this.enlightEnpassant();
   }
 
-  static GetColorClass(c) {
-    if (c == 'w')
-      return "white";
-    if (c == 'b')
-      return "black";
-    return "other-color"; //unidentified color
+  // Include square of the en-passant capturing square:
+  enlightEnpassant() {
+    // NOTE: shortcut, pawn has only one attack type, doesn't depend on square
+    const steps = this.pieces(this.playerColor)["p"].attack[0].steps;
+    for (let step of steps) {
+      const x = this.epSquare.x - step[0],
+            y = this.getY(this.epSquare.y - step[1]);
+      if (
+        this.onBoard(x, y) &&
+        this.getColor(x, y) == this.playerColor &&
+        this.getPieceType(x, y) == "p"
+      ) {
+        this.enlightened[x][this.epSquare.y] = true;
+        break;
+      }
+    }
   }
 
-  // Assume square i,j isn't empty
-  getPiece(i, j) {
-    if (typeof j == "string")
-      return j; //reserves
-    return this.board[i][j].charAt(1);
-  }
+  // Apply diff this.enlightened --> oldEnlightened on board
+  graphUpdateEnlightened() {
+    let chessboard =
+      document.getElementById(this.containerId).querySelector(".chessboard");
+    const r = chessboard.getBoundingClientRect();
+    const pieceWidth = this.getPieceWidth(r.width);
+    for (let x=0; x<this.size.x; x++) {
+      for (let y=0; y<this.size.y; y++) {
+        if (!this.enlightened[x][y] && this.oldEnlightened[x][y]) {
+          let elt = document.getElementById(this.coordsToId({x: x, y: y}));
+          elt.classList.add("in-shadow");
+          if (this.g_pieces[x][y])
+            this.g_pieces[x][y].classList.add("hidden");
+        }
+        else if (this.enlightened[x][y] && !this.oldEnlightened[x][y]) {
+          let elt = document.getElementById(this.coordsToId({x: x, y: y}));
+          elt.classList.remove("in-shadow");
+          if (this.g_pieces[x][y])
+            this.g_pieces[x][y].classList.remove("hidden");
+        }
+      }
+    }
+  }
+
+  //////////////
+  // BASIC UTILS
+
+  get size() {
+    return {
+      x: 8,
+      y: 8,
+      ratio: 1 //for rectangular board = y / x (optional, 1 = default)
+    };
+  }
+
+  // Color of thing on square (i,j). '' if square is empty
+  getColor(i, j) {
+    if (typeof i == "string")
+      return i; //reserves
+    return this.board[i][j].charAt(0);
+  }
+
+  static GetColorClass(c) {
+    if (c == 'w')
+      return "white";
+    if (c == 'b')
+      return "black";
+    return "other-color"; //unidentified color
+  }
+
+  // Piece on i,j. '' if square is empty
+  getPiece(i, j) {
+    if (typeof j == "string")
+      return j; //reserves
+    return this.board[i][j].charAt(1);
+  }
 
   // Piece type on square (i,j)
-  getPieceType(i, j) {
-    const p = this.getPiece(i, j);
-    return C.CannibalKings[p] || p; //a cannibal king move as...
+  getPieceType(x, y, p) {
+    if (!p)
+      p = this.getPiece(x, y);
+    return this.pieces()[p].moveas || p;
+  }
+
+  isKing(x, y, p) {
+    if (!p)
+      p = this.getPiece(x, y);
+    if (!this.options["cannibal"])
+      return p == 'k';
+    return !!C.CannibalKings[p];
   }
 
   // Get opponent color
@@ -1086,11 +1191,6 @@ export default class ChessRules {
     return (color == "w" ? "b" : "w");
   }
 
-  // Can thing on square1 capture (no return) thing on square2?
-  canTake([x1, y1], [x2, y2]) {
-    return (this.getColor(x1, y1) !== this.getColor(x2, y2));
-  }
-
   // Is (x,y) on the chessboard?
   onBoard(x, y) {
     return (x >= 0 && x < this.size.x &&
@@ -1125,14 +1225,12 @@ export default class ChessRules {
           }
         ]
       },
-      // rook
       'r': {
         "class": "rook",
         moves: [
           {steps: [[0, 1], [0, -1], [1, 0], [-1, 0]]}
         ]
       },
-      // knight
       'n': {
         "class": "knight",
         moves: [
@@ -1145,14 +1243,12 @@ export default class ChessRules {
           }
         ]
       },
-      // bishop
       'b': {
         "class": "bishop",
         moves: [
           {steps: [[1, 1], [1, -1], [-1, 1], [-1, -1]]}
         ]
       },
-      // queen
       'q': {
         "class": "queen",
         moves: [
@@ -1164,7 +1260,6 @@ export default class ChessRules {
           }
         ]
       },
-      // king
       'k': {
         "class": "king",
         moves: [
@@ -1186,8 +1281,31 @@ export default class ChessRules {
     };
   }
 
-  ////////////////////
-  // MOVES GENERATION
+  // NOTE: using special symbols to not interfere with variants' pieces codes
+  static get CannibalKings() {
+    return {
+      "!": "p",
+      "#": "r",
+      "$": "n",
+      "%": "b",
+      "*": "q",
+      "k": "k"
+    };
+  }
+
+  static get CannibalKingCode() {
+    return {
+      "p": "!",
+      "r": "#",
+      "n": "$",
+      "b": "%",
+      "q": "*",
+      "k": "k"
+    };
+  }
+
+  //////////////////////////
+  // MOVES GENERATION UTILS
 
   // For Cylinder: get Y coordinate
   getY(y) {
@@ -1199,36 +1317,116 @@ export default class ChessRules {
     return res;
   }
 
+  getSegments(curSeg, segStart, segEnd) {
+    if (curSeg.length == 0)
+      return undefined;
+    let segments = JSON.parse(JSON.stringify(curSeg)); //not altering
+    segments.push([[segStart[0], segStart[1]], [segEnd[0], segEnd[1]]]);
+    return segments;
+  }
+
+  getStepSpec(color, x, y, piece) {
+    return this.pieces(color, x, y)[piece || this.getPieceType(x, y)];
+  }
+
+  // Can thing on square1 capture thing on square2?
+  canTake([x1, y1], [x2, y2]) {
+    return this.getColor(x1, y1) !== this.getColor(x2, y2);
+  }
+
+  canStepOver(i, j, p) {
+    // In some variants, objects on boards don't stop movement (Chakart)
+    return this.board[i][j] == "";
+  }
+
+  canDrop([c, p], [i, j]) {
+    return (
+      this.board[i][j] == "" &&
+      (!this.enlightened || this.enlightened[i][j]) &&
+      (
+        p != "p" ||
+        (c == 'w' && i < this.size.x - 1) ||
+        (c == 'b' && i > 0)
+      )
+    );
+  }
+
+  // For Madrasi:
+  // (redefined in Baroque etc, where Madrasi condition doesn't make sense)
+  isImmobilized([x, y]) {
+    if (!this.options["madrasi"])
+      return false;
+    const color = this.getColor(x, y);
+    const oppCol = C.GetOppCol(color);
+    const piece = this.getPieceType(x, y);
+    const stepSpec = this.getStepSpec(color, x, y, piece);
+    const attacks = stepSpec.attack || stepSpec.moves;
+    for (let a of attacks) {
+      outerLoop: for (let step of a.steps) {
+        let [i, j] = [x + step[0], y + step[1]];
+        let stepCounter = 1;
+        while (this.onBoard(i, j) && this.board[i][j] == "") {
+          if (a.range <= stepCounter++)
+            continue outerLoop;
+          i += step[0];
+          j = this.getY(j + step[1]);
+        }
+        if (
+          this.onBoard(i, j) &&
+          this.getColor(i, j) == oppCol &&
+          this.getPieceType(i, j) == piece
+        ) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
   // Stop at the first capture found
   atLeastOneCapture(color) {
-    color = color || this.turn;
     const oppCol = C.GetOppCol(color);
-    for (let i = 0; i < this.size.x; i++) {
-      for (let j = 0; j < this.size.y; j++) {
-        if (this.board[i][j] != "" && this.getColor(i, j) == color) {
-          const allSpecs = this.pieces(color, i, j)
-          let specs = allSpecs[this.getPieceType(i, j)];
-          const attacks = specs.attack || specs.moves;
-          for (let a of attacks) {
-            outerLoop: for (let step of a.steps) {
-              let [ii, jj] = [i + step[0], this.getY(j + step[1])];
-              let stepCounter = 1;
-              while (this.onBoard(ii, jj) && this.board[ii][jj] == "") {
-                if (a.range <= stepCounter++)
-                  continue outerLoop;
-                ii += step[0];
-                jj = this.getY(jj + step[1]);
-              }
-              if (
-                this.onBoard(ii, jj) &&
-                this.getColor(ii, jj) == oppCol &&
-                this.filterValid(
-                  [this.getBasicMove([i, j], [ii, jj])]
-                ).length >= 1
-              ) {
-                return true;
-              }
-            }
+    const allowed = (sq1, sq2) => {
+      return (
+        // NOTE: canTake is reversed for Zen.
+        // Generally ok because of the symmetry. TODO?
+        this.canTake(sq1, sq2) &&
+        this.filterValid(
+          [this.getBasicMove(sq1, sq2)]).length >= 1
+      );
+    };
+    for (let i=0; i<this.size.x; i++) {
+      for (let j=0; j<this.size.y; j++) {
+        if (this.getColor(i, j) == color) {
+          if (
+            (
+              !this.options["zen"] &&
+              this.findDestSquares(
+                [i, j],
+                {
+                  attackOnly: true,
+                  one: true,
+                  segments: this.options["cylinder"]
+                },
+                allowed
+              )
+            )
+            ||
+            (
+              (
+                this.options["zen"] &&
+                this.findCapturesOn(
+                  [i, j],
+                  {
+                    one: true,
+                    segments: this.options["cylinder"]
+                  },
+                  allowed
+                )
+              )
+            )
+          ) {
+            return true;
           }
         }
       }
@@ -1236,6 +1434,38 @@ export default class ChessRules {
     return false;
   }
 
+  compatibleStep([x1, y1], [x2, y2], step, range) {
+    const epsilon = 1e-7; //arbitrary small value
+    let shifts = [0];
+    if (this.options["cylinder"])
+      Array.prototype.push.apply(shifts, [-this.size.y, this.size.y]);
+    for (let sh of shifts) {
+      const rx = (x2 - x1) / step[0],
+            ry = (y2 + sh - y1) / step[1];
+      if (
+        // Zero step but non-zero interval => impossible
+        (!Number.isFinite(rx) && !Number.isNaN(rx)) ||
+        (!Number.isFinite(ry) && !Number.isNaN(ry)) ||
+        // Negative number of step (impossible)
+        (rx < 0 || ry < 0) ||
+        // Not the same number of steps in both directions:
+        (!Number.isNaN(rx) && !Number.isNaN(ry) && Math.abs(rx - ry) > epsilon)
+      ) {
+        continue;
+      }
+      let distance = (Number.isNaN(rx) ? ry : rx);
+      if (Math.abs(distance - Math.round(distance)) > epsilon)
+        continue;
+      distance = Math.round(distance); //in case of (numerical...)
+      if (!range || range >= distance)
+        return true;
+    }
+    return false;
+  }
+
+  ////////////////////
+  // MOVES GENERATION
+
   getDropMovesFrom([c, p]) {
     // NOTE: by design, this.reserve[c][p] >= 1 on user click
     // (but not necessarily otherwise: atLeastOneMove() etc)
@@ -1244,23 +1474,22 @@ export default class ChessRules {
     let moves = [];
     for (let i=0; i<this.size.x; i++) {
       for (let j=0; j<this.size.y; j++) {
-        if (
-          this.board[i][j] == "" &&
-          (!this.enlightened || this.enlightened[i][j]) &&
-          (
-            p != "p" ||
-            (c == 'w' && i < this.size.x - 1) ||
-            (c == 'b' && i > 0)
-          )
-        ) {
-          moves.push(
-            new Move({
-              start: {x: c, y: p},
-              end: {x: i, y: j},
-              appear: [new PiPo({x: i, y: j, c: c, p: p})],
-              vanish: []
-            })
-          );
+        if (this.canDrop([c, p], [i, j])) {
+          let mv = new Move({
+            start: {x: c, y: p},
+            end: {x: i, y: j},
+            appear: [new PiPo({x: i, y: j, c: c, p: p})],
+            vanish: []
+          });
+          if (this.board[i][j] != "") {
+            mv.vanish.push(new PiPo({
+              x: i,
+              y: j,
+              c: this.getColor(i, j),
+              p: this.getPiece(i, j)
+            }));
+          }
+          moves.push(mv);
         }
       }
     }
@@ -1268,28 +1497,22 @@ export default class ChessRules {
   }
 
   // All possible moves from selected square
-  getPotentialMovesFrom(sq, color) {
+  getPotentialMovesFrom([x, y], color) {
     if (this.subTurnTeleport == 2)
       return [];
-    if (typeof sq[0] == "string")
-      return this.getDropMovesFrom(sq);
-    if (this.isImmobilized(sq))
+    if (typeof x == "string")
+      return this.getDropMovesFrom([x, y]);
+    if (this.isImmobilized([x, y]))
       return [];
-    const piece = this.getPieceType(sq[0], sq[1]);
-    let moves = this.getPotentialMovesOf(piece, sq);
-    if (
-      piece == "p" &&
-      this.hasEnpassant &&
-      this.epSquare
-    ) {
-      Array.prototype.push.apply(moves, this.getEnpassantCaptures(sq));
-    }
+    const piece = this.getPieceType(x, y);
+    let moves = this.getPotentialMovesOf(piece, [x, y]);
+    if (piece == "p" && this.hasEnpassant && this.epSquare)
+      Array.prototype.push.apply(moves, this.getEnpassantCaptures([x, y]));
     if (
-      piece == "k" &&
-      this.hasCastle &&
+      this.isKing(0, 0, piece) && this.hasCastle &&
       this.castleFlags[color || this.turn].some(v => v < this.size.y)
     ) {
-      Array.prototype.push.apply(moves, this.getCastleMoves(sq));
+      Array.prototype.push.apply(moves, this.getCastleMoves([x, y]));
     }
     return this.postProcessPotentialMoves(moves);
   }
@@ -1300,11 +1523,11 @@ export default class ChessRules {
     const color = this.getColor(moves[0].start.x, moves[0].start.y);
     const oppCol = C.GetOppCol(color);
 
-    if (this.options["capture"] && this.atLeastOneCapture())
+    if (this.options["capture"] && this.atLeastOneCapture(color))
       moves = this.capturePostProcess(moves, oppCol);
 
     if (this.options["atomic"])
-      this.atomicPostProcess(moves, oppCol);
+      this.atomicPostProcess(moves, color, oppCol);
 
     if (
       moves.length > 0 &&
@@ -1313,13 +1536,9 @@ export default class ChessRules {
       this.pawnPostProcess(moves, color, oppCol);
     }
 
-    if (
-      this.options["cannibal"] &&
-      this.options["rifle"]
-    ) {
+    if (this.options["cannibal"] && this.options["rifle"])
       // In this case a rifle-capture from last rank may promote a pawn
       this.riflePromotePostProcess(moves, color);
-    }
 
     return moves;
   }
@@ -1335,7 +1554,7 @@ export default class ChessRules {
     });
   }
 
-  atomicPostProcess(moves, oppCol) {
+  atomicPostProcess(moves, color, oppCol) {
     moves.forEach(m => {
       if (
         this.board[m.end.x][m.end.y] != "" &&
@@ -1352,15 +1571,22 @@ export default class ChessRules {
           [1, 0],
           [1, 1]
         ];
+        let mNext = new Move({
+          start: m.end,
+          end: m.end,
+          appear: [],
+          vanish: []
+        });
         for (let step of steps) {
           let x = m.end.x + step[0];
           let y = this.getY(m.end.y + step[1]);
           if (
             this.onBoard(x, y) &&
             this.board[x][y] != "" &&
+            (x != m.start.x || y != m.start.y) &&
             this.getPieceType(x, y) != "p"
           ) {
-            m.vanish.push(
+            mNext.vanish.push(
               new PiPo({
                 p: this.getPiece(x, y),
                 c: this.getColor(x, y),
@@ -1370,8 +1596,18 @@ export default class ChessRules {
             );
           }
         }
-        if (!this.options["rifle"])
-          m.appear.pop(); //nothing appears
+        if (!this.options["rifle"]) {
+          // The moving piece also vanish
+          mNext.vanish.unshift(
+            new PiPo({
+              x: m.end.x,
+              y: m.end.y,
+              c: color,
+              p: this.getPiece(m.start.x, m.start.y)
+            })
+          );
+        }
+        m.next = mNext;
       }
     });
   }
@@ -1441,114 +1677,123 @@ export default class ChessRules {
     Array.prototype.push.apply(moves, newMoves);
   }
 
-  // NOTE: using special symbols to not interfere with variants' pieces codes
-  static get CannibalKings() {
-    return {
-      "!": "p",
-      "#": "r",
-      "$": "n",
-      "%": "b",
-      "*": "q",
-      "k": "k"
-    };
-  }
-
-  static get CannibalKingCode() {
-    return {
-      "p": "!",
-      "r": "#",
-      "n": "$",
-      "b": "%",
-      "q": "*",
-      "k": "k"
-    };
-  }
-
-  isKing(symbol) {
-    return !!C.CannibalKings[symbol];
-  }
-
-  // For Madrasi:
-  // (redefined in Baroque etc, where Madrasi condition doesn't make sense)
-  isImmobilized([x, y]) {
-    if (!this.options["madrasi"])
-      return false;
+  // Generic method to find possible moves of "sliding or jumping" pieces
+  getPotentialMovesOf(piece, [x, y]) {
     const color = this.getColor(x, y);
-    const oppCol = C.GetOppCol(color);
-    const piece = this.getPieceType(x, y); //ok not cannibal king
-    const stepSpec = this.pieces(color, x, y)[piece];
-    const attacks = stepSpec.attack || stepSpec.moves;
-    for (let a of attacks) {
-      outerLoop: for (let step of a.steps) {
-        let [i, j] = [x + step[0], y + step[1]];
-        let stepCounter = 1;
-        while (this.onBoard(i, j) && this.board[i][j] == "") {
-          if (a.range <= stepCounter++)
-            continue outerLoop;
-          i += step[0];
-          j = this.getY(j + step[1]);
-        }
-        if (
-          this.onBoard(i, j) &&
-          this.getColor(i, j) == oppCol &&
-          this.getPieceType(i, j) == piece
-        ) {
-          return true;
+    const stepSpec = this.getStepSpec(color, x, y, piece);
+    let squares = [];
+    if (stepSpec.attack) {
+      squares = this.findDestSquares(
+        [x, y],
+        {
+          attackOnly: true,
+          segments: this.options["cylinder"],
+          stepSpec: stepSpec
+        },
+        ([i1, j1], [i2, j2]) => {
+          return (
+            (!this.options["zen"] || this.isKing(i2, j2)) &&
+            this.canTake([i1, j1], [i2, j2])
+          );
         }
+      );
+    }
+    const noSpecials = this.findDestSquares(
+      [x, y],
+      {
+        moveOnly: !!stepSpec.attack || this.options["zen"],
+        segments: this.options["cylinder"],
+        stepSpec: stepSpec
       }
+    );
+    Array.prototype.push.apply(squares, noSpecials);
+    if (this.options["zen"]) {
+      let zenCaptures = this.findCapturesOn(
+        [x, y],
+        {}, //byCol: default is ok
+        ([i1, j1], [i2, j2]) =>
+          !this.isKing(i1, j1) && this.canTake([i2, j2], [i1, j1])
+      );
+      // Technical step: segments (if any) are reversed
+      if (this.options["cylinder"]) {
+        zenCaptures.forEach(z => {
+          z.segments = z.segments.reverse().map(s => s.reverse())
+        });
+      }
+      Array.prototype.push.apply(squares, zenCaptures);
     }
-    return false;
-  }
-
-  canStepOver(i, j) {
-    // In some variants, objects on boards don't stop movement (Chakart)
-    return this.board[i][j] == "";
+    if (
+      this.options["recycle"] ||
+      (this.options["teleport"] && this.subTurnTeleport == 1)
+    ) {
+      const selfCaptures = this.findDestSquares(
+        [x, y],
+        {
+          attackOnly: true,
+          segments: this.options["cylinder"],
+          stepSpec: stepSpec
+        },
+        ([i1, j1], [i2, j2]) =>
+          this.getColor(i2, j2) == color && !this.isKing(i2, j2)
+      );
+      Array.prototype.push.apply(squares, selfCaptures);
+    }
+    return squares.map(s => {
+      let mv = this.getBasicMove([x, y], s.sq);
+      if (this.options["cylinder"] && s.segments.length >= 2)
+        mv.segments = s.segments;
+      return mv;
+    });
   }
 
-  // Generic method to find possible moves of "sliding or jumping" pieces
-  getPotentialMovesOf(piece, [x, y]) {
-    const color = this.getColor(x, y);
-    const stepSpec = this.pieces(color, x, y)[piece];
-    let moves = [];
-    // Next 3 for Cylinder mode:
+  findDestSquares([x, y], o, allowed) {
+    if (!allowed)
+      allowed = (sq1, sq2) => this.canTake(sq1, sq2);
+    const apparentPiece = this.getPiece(x, y); //how it looks
+    let res = [];
+    // Next 3 for Cylinder mode: (unused if !o.segments)
     let explored = {};
     let segments = [];
     let segStart = [];
-
-    const addMove = (start, end) => {
-      let newMove = this.getBasicMove(start, end);
-      if (segments.length > 0) {
-        newMove.segments = JSON.parse(JSON.stringify(segments));
-        newMove.segments.push([[segStart[0], segStart[1]], [end[0], end[1]]]);
-      }
-      moves.push(newMove);
+    const addSquare = ([i, j]) => {
+      let elt = {sq: [i, j]};
+      if (o.segments)
+        elt.segments = this.getSegments(segments, segStart, end);
+      res.push(elt);
     };
-
-    const findAddMoves = (type, stepArray) => {
+    const exploreSteps = (stepArray) => {
       for (let s of stepArray) {
         outerLoop: for (let step of s.steps) {
-          segments = [];
-          segStart = [x, y];
+          if (o.segments) {
+            segments = [];
+            segStart = [x, y];
+          }
           let [i, j] = [x, y];
           let stepCounter = 0;
           while (
             this.onBoard(i, j) &&
-            (this.canStepOver(i, j) || (i == x && j == y))
+            ((i == x && j == y) || this.canStepOver(i, j, apparentPiece))
           ) {
-            if (
-              type != "attack" &&
-              !explored[i + "." + j] &&
-              (i != x || j != y)
-            ) {
+            if (!explored[i + "." + j] && (i != x || j != y)) {
               explored[i + "." + j] = true;
-              addMove([x, y], [i, j]);
+              if (
+                !o.captureTarget ||
+                (o.captureTarget[0] == i && o.captureTarget[1] == j)
+              ) {
+                if (o.one && !o.attackOnly)
+                  return true;
+                if (!o.attackOnly)
+                  addSquare(!o.captureTarget ? [i, j] : [x, y]);
+                if (o.captureTarget)
+                  return res[0];
+              }
             }
             if (s.range <= stepCounter++)
               continue outerLoop;
             const oldIJ = [i, j];
             i += step[0];
             j = this.getY(j + step[1]);
-            if (Math.abs(j - oldIJ[1]) > 1) {
+            if (o.segments && Math.abs(j - oldIJ[1]) > 1) {
               // Boundary between segments (cylinder mode)
               segments.push([[segStart[0], segStart[1]], oldIJ]);
               segStart = [i, j];
@@ -1557,106 +1802,88 @@ export default class ChessRules {
           if (!this.onBoard(i, j))
             continue;
           const pieceIJ = this.getPieceType(i, j);
-          if (
-            type != "moveonly" &&
-            !explored[i + "." + j] &&
-            (
-              !this.options["zen"] ||
-              pieceIJ == "k"
-            ) &&
-            (
-              this.canTake([x, y], [i, j]) ||
-              (
-                (this.options["recycle"] || this.options["teleport"]) &&
-                pieceIJ != "k"
-              )
-            )
-          ) {
+          if (!explored[i + "." + j]) {
             explored[i + "." + j] = true;
-            addMove([x, y], [i, j]);
+            if (allowed([x, y], [i, j])) {
+              if (o.one && !o.moveOnly)
+                return true;
+              if (!o.moveOnly)
+                addSquare(!o.captureTarget ? [i, j] : [x, y]);
+              if (
+                o.captureTarget &&
+                o.captureTarget[0] == i && o.captureTarget[1] == j
+              ) {
+                return res[0];
+              }
+            }
           }
         }
       }
+      return undefined; //default, but let's explicit it
     };
-
-    const specialAttack = !!stepSpec.attack;
-    if (specialAttack)
-      findAddMoves("attack", stepSpec.attack);
-    findAddMoves(specialAttack ? "moveonly" : "all", stepSpec.moves);
-    if (this.options["zen"]) {
-      Array.prototype.push.apply(moves,
-                                 this.findCapturesOn([x, y], {zen: true}));
+    if (o.captureTarget)
+      return exploreSteps(o.captureSteps)
+    else {
+      const stepSpec =
+        o.stepSpec || this.getStepSpec(this.getColor(x, y), x, y);
+      let outOne = false;
+      if (!o.attackOnly || !stepSpec.attack)
+        outOne = exploreSteps(stepSpec.moves);
+      if (!outOne && !o.moveOnly && !!stepSpec.attack) {
+        o.attackOnly = true; //ok because o is always a temporary object
+        outOne = exploreSteps(stepSpec.attack);
+      }
+      return (o.one ? outOne : res);
     }
-    return moves;
   }
 
   // Search for enemy (or not) pieces attacking [x, y]
-  findCapturesOn([x, y], args) {
-    let moves = [];
-    if (!args.oppCol)
-      args.oppCol = C.GetOppCol(this.getColor(x, y) || this.turn);
+  findCapturesOn([x, y], o, allowed) {
+    if (!o.byCol)
+      o.byCol = [C.GetOppCol(this.getColor(x, y) || this.turn)];
+    let res = [];
     for (let i=0; i<this.size.x; i++) {
       for (let j=0; j<this.size.y; j++) {
+        const colIJ = this.getColor(i, j);
         if (
           this.board[i][j] != "" &&
-          this.getColor(i, j) == args.oppCol &&
+          o.byCol.includes(colIJ) &&
           !this.isImmobilized([i, j])
         ) {
-          if (args.zen && this.isKing(this.getPiece(i, j)))
-            continue; //king not captured in this way
-          const stepSpec =
-            this.pieces(args.oppCol, i, j)[this.getPieceType(i, j)];
+          const apparentPiece = this.getPiece(i, j);
+          // Quick check: does this potential attacker target x,y ?
+          if (this.canStepOver(x, y, apparentPiece))
+            continue;
+          const stepSpec = this.getStepSpec(colIJ, i, j);
           const attacks = stepSpec.attack || stepSpec.moves;
           for (let a of attacks) {
             for (let s of a.steps) {
               // Quick check: if step isn't compatible, don't even try
-              if (!C.CompatibleStep([i, j], [x, y], s, a.range))
+              if (!this.compatibleStep([i, j], [x, y], s, a.range))
                 continue;
               // Finally verify that nothing stand in-between
-              let [ii, jj] = [i + s[0], this.getY(j + s[1])];
-              let stepCounter = 1;
-              while (
-                this.onBoard(ii, jj) &&
-                this.board[ii][jj] == "" &&
-                (ii != x || jj != y) //condition to attack empty squares too
-              ) {
-                ii += s[0];
-                jj = this.getY(jj + s[1]);
-              }
-              if (ii == x && jj == y) {
-                if (args.zen)
-                  // Reverse capture:
-                  moves.push(this.getBasicMove([x, y], [i, j]));
-                else
-                  moves.push(this.getBasicMove([i, j], [x, y]));
-                if (args.one)
-                  return moves; //test for underCheck
+              const out = this.findDestSquares(
+                [i, j],
+                {
+                  captureTarget: [x, y],
+                  captureSteps: [{steps: [s], range: a.range}],
+                  segments: o.segments,
+                  attackOnly: true,
+                  one: false //one and captureTarget are mutually exclusive
+                },
+                allowed
+              );
+              if (out) {
+                if (o.one)
+                  return true;
+                res.push(out);
               }
             }
           }
         }
       }
     }
-    return moves;
-  }
-
-  static CompatibleStep([x1, y1], [x2, y2], step, range) {
-    const rx = (x2 - x1) / step[0],
-          ry = (y2 - y1) / step[1];
-    if (
-      (!Number.isFinite(rx) && !Number.isNaN(rx)) ||
-      (!Number.isFinite(ry) && !Number.isNaN(ry))
-    ) {
-      return false;
-    }
-    let distance = (Number.isNaN(rx) ? ry : rx);
-    // TODO: 1e-7 here is totally arbitrary
-    if (Math.abs(distance - Math.round(distance)) > 1e-7)
-      return false;
-    distance = Math.round(distance); //in case of (numerical...)
-    if (range < distance)
-      return false;
-    return true;
+    return (o.one ? false : res);
   }
 
   // Build a regular move from its initial and destination squares.
@@ -1703,9 +1930,9 @@ export default class ChessRules {
         })
       );
       if (this.options["cannibal"] && destColor != initColor) {
-        const lastIdx = mv.vanish.length - 1;
+        const lastIdx = mv.vanish.length - 1; //think "Rifle+Cannibal"
         let trPiece = mv.vanish[lastIdx].p;
-        if (this.isKing(this.getPiece(sx, sy)))
+        if (this.isKing(sx, sy))
           trPiece = C.CannibalKingCode[trPiece];
         if (mv.appear.length >= 1)
           mv.appear[0].p = trPiece;
@@ -1748,8 +1975,15 @@ export default class ChessRules {
       s.y == e.y &&
       Math.abs(s.x - e.x) == 2 &&
       // Next conditions for variants like Atomic or Rifle, Recycle...
-      (move.appear.length > 0 && move.appear[0].p == "p") &&
-      (move.vanish.length > 0 && move.vanish[0].p == "p")
+      (
+        move.appear.length > 0 &&
+        this.getPieceType(0, 0, move.appear[0].p) == 'p'
+      )
+      &&
+      (
+        move.vanish.length > 0 &&
+        this.getPieceType(0, 0, move.vanish[0].p) == 'p'
+      )
     ) {
       return {
         x: (s.x + e.x) / 2,
@@ -1764,25 +1998,26 @@ export default class ChessRules {
     const color = this.getColor(x, y);
     const shiftX = (color == 'w' ? -1 : 1);
     const oppCol = C.GetOppCol(color);
-    let enpassantMove = null;
     if (
-      !!this.epSquare &&
+      this.epSquare &&
       this.epSquare.x == x + shiftX &&
       Math.abs(this.getY(this.epSquare.y - y)) == 1 &&
-      this.getColor(x, this.epSquare.y) == oppCol //Doublemove guard...
+      // Doublemove (and Progressive?) guards:
+      this.board[this.epSquare.x][this.epSquare.y] == "" &&
+      this.getColor(x, this.epSquare.y) == oppCol
     ) {
       const [epx, epy] = [this.epSquare.x, this.epSquare.y];
-      this.board[epx][epy] = oppCol + "p";
-      enpassantMove = this.getBasicMove([x, y], [epx, epy]);
+      this.board[epx][epy] = oppCol + 'p';
+      let enpassantMove = this.getBasicMove([x, y], [epx, epy]);
       this.board[epx][epy] = "";
       const lastIdx = enpassantMove.vanish.length - 1; //think Rifle
       enpassantMove.vanish[lastIdx].x = x;
+      return [enpassantMove];
     }
-    return !!enpassantMove ? [enpassantMove] : [];
+    return [];
   }
 
-  // "castleInCheck" arg to let some variants castle under check
-  getCastleMoves([x, y], finalSquares, castleInCheck, castleWith) {
+  getCastleMoves([x, y], finalSquares, castleWith) {
     const c = this.getColor(x, y);
 
     // Castling ?
@@ -1807,7 +2042,7 @@ export default class ChessRules {
       if (
         this.board[x][rookPos] == "" ||
         this.getColor(x, rookPos) != c ||
-        (!!castleWith && !castleWith.includes(castlingPiece))
+        (castleWith && !castleWith.includes(castlingPiece))
       ) {
         // Rook is not here, or changed color (see Benedict)
         continue;
@@ -1818,7 +2053,13 @@ export default class ChessRules {
       let i = y;
       do {
         if (
-          (!castleInCheck && this.underCheck([x, i], oppCol)) ||
+          // NOTE: next weird test because underCheck() verification
+          // will be executed in filterValid() later.
+          (
+            i != finalSquares[castleSide][0] &&
+            this.underCheck([x, i], oppCol)
+          )
+          ||
           (
             this.board[x][i] != "" &&
             // NOTE: next check is enough, because of chessboard constraints
@@ -1850,7 +2091,7 @@ export default class ChessRules {
         }
       }
 
-      // If this code is reached, castle is valid
+      // If this code is reached, castle is potentially valid
       moves.push(
         new Move({
           appear: [
@@ -1886,70 +2127,91 @@ export default class ChessRules {
   ////////////////////
   // MOVES VALIDATION
 
-  // Is (king at) given position under check by "oppCol" ?
-  underCheck([x, y], oppCol) {
-    if (this.options["taking"] || this.options["dark"])
-      return false;
+  // Is piece (or square) at given position attacked by "oppCol" ?
+  underAttack([x, y], oppCol) {
+    // An empty square is considered as king,
+    // since it's used only in getCastleMoves (TODO?)
+    const king = this.board[x][y] == "" || this.isKing(x, y);
     return (
-      this.findCapturesOn([x, y], {oppCol: oppCol, one: true}).length >= 1
+      (
+        (!this.options["zen"] || king) &&
+        this.findCapturesOn(
+          [x, y],
+          {
+            byCol: [oppCol],
+            segments: this.options["cylinder"],
+            one: true
+          }
+        )
+      )
+      ||
+      (
+        (!!this.options["zen"] && !king) &&
+        this.findDestSquares(
+          [x, y],
+          {
+            attackOnly: true,
+            segments: this.options["cylinder"],
+            one: true
+          },
+          ([i1, j1], [i2, j2]) => this.getColor(i2, j2) == oppCol
+        )
+      )
     );
   }
 
-  // Stop at first king found (TODO: multi-kings)
+  // Argument is (very generally) an array of squares (= arrays)
+  underCheck(square_s, oppCol) {
+    if (this.options["taking"] || this.options["dark"])
+      return false;
+    if (!Array.isArray(square_s[0]))
+      square_s = [square_s];
+    return square_s.some(sq => this.underAttack(sq, oppCol));
+  }
+
+  // Scan board for king(s)
   searchKingPos(color) {
+    let res = [];
     for (let i=0; i < this.size.x; i++) {
       for (let j=0; j < this.size.y; j++) {
-        if (this.getColor(i, j) == color && this.isKing(this.getPiece(i, j)))
-          return [i, j];
+        if (this.getColor(i, j) == color && this.isKing(i, j))
+          res.push([i, j]);
       }
     }
-    return [-1, -1]; //king not found
+    return res;
   }
 
-  filterValid(moves) {
-    if (moves.length == 0)
-      return [];
-    const color = this.turn;
+  // 'color' arg because some variants (e.g. Refusal) check opponent moves
+  filterValid(moves, color) {
+    if (!color)
+      color = this.turn;
     const oppCol = C.GetOppCol(color);
-    if (this.options["balance"] && [1, 3].includes(this.movesCount)) {
-      // Forbid moves either giving check or exploding opponent's king:
-      const oppKingPos = this.searchKingPos(oppCol);
-      moves = moves.filter(m => {
-        if (
-          m.vanish.some(v => v.c == oppCol && v.p == "k") &&
-          m.appear.every(a => a.c != oppCol || a.p != "k")
-        )
-          return false;
-        this.playOnBoard(m);
-        const res = !this.underCheck(oppKingPos, color);
-        this.undoOnBoard(m);
-        return res;
-      });
-    }
-    if (this.options["taking"] || this.options["dark"])
-      return moves;
-    const kingPos = this.searchKingPos(color);
+    let kingPos = this.searchKingPos(color);
     let filtered = {}; //avoid re-checking similar moves (promotions...)
     return moves.filter(m => {
       const key = m.start.x + m.start.y + '.' + m.end.x + m.end.y;
       if (!filtered[key]) {
         this.playOnBoard(m);
-        let square = kingPos,
+        let newKingPP = null,
+            sqIdx = 0,
             res = true; //a priori valid
-        if (m.vanish.some(v => {
-          return C.CannibalKings[v.p] && v.c == color;
-        })) {
+        const oldKingPP =
+          m.vanish.find(v => this.isKing(0, 0, v.p) && v.c == color);
+        if (oldKingPP) {
           // Search king in appear array:
-          const newKingIdx =
-            m.appear.findIndex(a => {
-              return C.CannibalKings[a.p] && a.c == color;
-            });
-          if (newKingIdx >= 0)
-            square = [m.appear[newKingIdx].x, m.appear[newKingIdx].y];
+          newKingPP =
+            m.appear.find(a => this.isKing(0, 0, a.p) && a.c == color);
+          if (newKingPP) {
+            sqIdx = kingPos.findIndex(kp =>
+              kp[0] == oldKingPP.x && kp[1] == oldKingPP.y);
+            kingPos[sqIdx] = [newKingPP.x, newKingPP.y];
+          }
           else
-            res = false;
+            res = false; //king vanished
         }
-        res &&= !this.underCheck(square, oppCol);
+        res &&= !this.underCheck(kingPos, oppCol);
+        if (oldKingPP && newKingPP)
+          kingPos[sqIdx] = [oldKingPP.x, oldKingPP.y];
         this.undoOnBoard(m);
         filtered[key] = res;
         return res;
@@ -1961,16 +2223,6 @@ export default class ChessRules {
   /////////////////
   // MOVES PLAYING
 
-  // Aggregate flags into one object
-  aggregateFlags() {
-    return this.castleFlags;
-  }
-
-  // Reverse operation
-  disaggregateFlags(flags) {
-    this.castleFlags = flags;
-  }
-
   // Apply a move on board
   playOnBoard(move) {
     for (let psq of move.vanish)
@@ -1989,12 +2241,8 @@ export default class ChessRules {
   updateCastleFlags(move) {
     // Update castling flags if start or arrive from/at rook/king locations
     move.appear.concat(move.vanish).forEach(psq => {
-      if (
-        this.board[psq.x][psq.y] != "" &&
-        this.getPieceType(psq.x, psq.y) == "k"
-      ) {
+      if (this.isKing(0, 0, psq.p))
         this.castleFlags[psq.c] = [this.size.y, this.size.y];
-      }
       // NOTE: not "else if" because king can capture enemy rook...
       let c = "";
       if (psq.x == 0)
@@ -2013,8 +2261,8 @@ export default class ChessRules {
     if (
       this.hasCastle &&
       // If flags already off, no need to re-check:
-      Object.keys(this.castleFlags).some(c => {
-        return this.castleFlags[c].some(val => val < this.size.y)})
+      Object.values(this.castleFlags).some(cvals =>
+        cvals.some(val => val < this.size.y))
     ) {
       this.updateCastleFlags(move);
     }
@@ -2030,7 +2278,7 @@ export default class ChessRules {
         const destSquare = C.CoordsToSquare(move.end);
         if (
           this.ispawn[initSquare] ||
-          (move.vanish[0].p == "p" && move.appear[0].p != "p")
+          (move.vanish[0].p == 'p' && move.appear[0].p != 'p')
         ) {
           this.ispawn[destSquare] = true;
         }
@@ -2038,7 +2286,7 @@ export default class ChessRules {
           this.ispawn[destSquare] &&
           this.getColor(move.end.x, move.end.y) != move.vanish[0].c
         ) {
-          move.vanish[1].p = "p";
+          move.vanish[1].p = 'p';
           delete this.ispawn[destSquare];
         }
       }
@@ -2080,14 +2328,13 @@ export default class ChessRules {
 
   postPlay(move) {
     const color = this.turn;
-    const oppCol = C.GetOppCol(color);
     if (this.options["dark"])
       this.updateEnlightened();
     if (this.options["teleport"]) {
       if (
         this.subTurnTeleport == 1 &&
         move.vanish.length > move.appear.length &&
-        move.vanish[move.vanish.length - 1].c == color
+        move.vanish[1].c == color
       ) {
         const v = move.vanish[move.vanish.length - 1];
         this.captured = {x: v.x, y: v.y, c: v.c, p: v.p};
@@ -2097,40 +2344,44 @@ export default class ChessRules {
       this.subTurnTeleport = 1;
       this.captured = null;
     }
-    if (this.options["balance"]) {
-      if (![1, 3].includes(this.movesCount))
-        this.turn = oppCol;
-    }
-    else {
-      if (
-        (
-          this.options["doublemove"] &&
-          this.movesCount >= 1 &&
-          this.subTurn == 1
-        ) ||
-        (this.options["progressive"] && this.subTurn <= this.movesCount)
-      ) {
-        const oppKingPos = this.searchKingPos(oppCol);
-        if (
-          oppKingPos[0] >= 0 &&
-          (
-            this.options["taking"] ||
-            !this.underCheck(oppKingPos, color)
-          )
-        ) {
-          this.subTurn++;
-          return;
-        }
-      }
-      this.turn = oppCol;
+    if (this.isLastMove(move)) {
+      this.turn = C.GetOppCol(color);
+      this.movesCount++;
+      this.subTurn = 1;
     }
-    this.movesCount++;
-    this.subTurn = 1;
+    else if (!move.next)
+      this.subTurn++;
+  }
+
+  isLastMove(move) {
+    if (move.next)
+      return false;
+    const color = this.turn;
+    const oppKingPos = this.searchKingPos(C.GetOppCol(color));
+    if (oppKingPos.length == 0 || this.underCheck(oppKingPos, color))
+      return true;
+    return (
+      (
+        !this.options["balance"] ||
+        ![1, 2].includes(this.movesCount) ||
+        this.subTurn == 2
+      )
+      &&
+      (
+        !this.options["doublemove"] ||
+        this.movesCount == 0 ||
+        this.subTurn == 2
+      )
+      &&
+      (
+        !this.options["progressive"] ||
+        this.subTurn == this.movesCount + 1
+      )
+    );
   }
 
   // "Stop at the first move found"
   atLeastOneMove(color) {
-    color = color || this.turn;
     for (let i = 0; i < this.size.x; i++) {
       for (let j = 0; j < this.size.y; j++) {
         if (this.board[i][j] != "" && this.getColor(i, j) == color) {
@@ -2156,17 +2407,20 @@ export default class ChessRules {
   getCurrentScore(move) {
     const color = this.turn;
     const oppCol = C.GetOppCol(color);
-    const kingPos = [this.searchKingPos(color), this.searchKingPos(oppCol)];
-    if (kingPos[0][0] < 0 && kingPos[1][0] < 0)
+    const kingPos = {
+      [color]: this.searchKingPos(color),
+      [oppCol]: this.searchKingPos(oppCol)
+    };
+    if (kingPos[color].length == 0 && kingPos[oppCol].length == 0)
       return "1/2";
-    if (kingPos[0][0] < 0)
+    if (kingPos[color].length == 0)
       return (color == "w" ? "0-1" : "1-0");
-    if (kingPos[1][0] < 0)
+    if (kingPos[oppCol].length == 0)
       return (color == "w" ? "1-0" : "0-1");
-    if (this.atLeastOneMove())
+    if (this.atLeastOneMove(color))
       return "*";
     // No valid move: stalemate or checkmate?
-    if (!this.underCheck(kingPos[0], color))
+    if (!this.underCheck(kingPos[color], oppCol))
       return "1/2";
     // OK, checkmate
     return (color == "w" ? "0-1" : "1-0");
@@ -2184,7 +2438,8 @@ export default class ChessRules {
     const pieceWidth = this.getPieceWidth(r.width);
     move.appear.forEach(a => {
       this.g_pieces[a.x][a.y] = document.createElement("piece");
-      C.AddClass_es(this.g_pieces[a.x][a.y], this.pieces()[a.p]["class"]);
+      C.AddClass_es(this.g_pieces[a.x][a.y],
+                    this.pieces(a.c, a.x, a.y)[a.p]["class"]);
       this.g_pieces[a.x][a.y].classList.add(C.GetColorClass(a.c));
       this.g_pieces[a.x][a.y].style.width = pieceWidth + "px";
       this.g_pieces[a.x][a.y].style.height = pieceWidth + "px";
@@ -2200,56 +2455,72 @@ export default class ChessRules {
       this.graphUpdateEnlightened();
   }
 
-  playPlusVisual(move, r) {
+  // TODO: send stack receive stack, or allow incremental? (good/bad points)
+  buildMoveStack(move, r) {
+    this.moveStack.push(move);
+    this.computeNextMove(move);
     this.play(move);
-    this.playVisual(move, r);
-    this.afterPlay(move); //user method
-  }
-
-  getMaxDistance(rwidth) {
-    // Works for all rectangular boards:
-    return Math.sqrt(rwidth ** 2 + (rwidth / this.size.ratio) ** 2);
+    const newTurn = this.turn;
+    if (this.moveStack.length == 1)
+      this.playVisual(move, r);
+    if (move.next) {
+      this.gameState = {
+        fen: this.getFen(),
+        board: JSON.parse(JSON.stringify(this.board)) //easier
+      };
+      this.buildMoveStack(move.next, r);
+    }
+    else {
+      if (this.moveStack.length == 1) {
+        // Usual case (one normal move)
+        this.afterPlay(this.moveStack, newTurn, {send: true, res: true});
+        this.moveStack = []
+      }
+      else {
+        this.afterPlay(this.moveStack, newTurn, {send: true, res: false});
+        this.re_initFromFen(this.gameState.fen, this.gameState.board);
+        this.playReceivedMove(this.moveStack.slice(1), () => {
+          this.afterPlay(this.moveStack, newTurn, {send: false, res: true});
+          this.moveStack = []
+        });
+      }
+    }
   }
 
-  getDomPiece(x, y) {
-    return (typeof x == "string" ? this.r_pieces : this.g_pieces)[x][y];
-  }
+  // Implemented in variants using (automatic) moveStack
+  computeNextMove(move) {}
 
-  animate(move, callback) {
-    if (this.noAnimate || move.noAnimate) {
-      callback();
-      return;
-    }
-    let initPiece = this.getDomPiece(move.start.x, move.start.y);
-    // NOTE: cloning generally not required, but light enough, and simpler
+  animateMoving(start, end, drag, segments, cb) {
+    let initPiece = this.getDomPiece(start.x, start.y);
+    // NOTE: cloning often not required, but light enough, and simpler
     let movingPiece = initPiece.cloneNode();
     initPiece.style.opacity = "0";
     let container =
       document.getElementById(this.containerId)
     const r = container.querySelector(".chessboard").getBoundingClientRect();
-    if (typeof move.start.x == "string") {
+    if (typeof start.x == "string") {
       // Need to bound width/height (was 100% for reserve pieces)
       const pieceWidth = this.getPieceWidth(r.width);
       movingPiece.style.width = pieceWidth + "px";
       movingPiece.style.height = pieceWidth + "px";
     }
-    const maxDist = this.getMaxDistance(r.width);
-    const pieces = this.pieces();
-    if (move.drag) {
-      const startCode = this.getPiece(move.start.x, move.start.y);
+    const maxDist = this.getMaxDistance(r);
+    const apparentColor = this.getColor(start.x, start.y);
+    const pieces = this.pieces(apparentColor, start.x, start.y);
+    if (drag) {
+      const startCode = this.getPiece(start.x, start.y);
       C.RemoveClass_es(movingPiece, pieces[startCode]["class"]);
-      C.AddClass_es(movingPiece, pieces[move.drag.p]["class"]);
-      const apparentColor = this.getColor(move.start.x, move.start.y);
-      if (apparentColor != move.drag.c) {
+      C.AddClass_es(movingPiece, pieces[drag.p]["class"]);
+      if (apparentColor != drag.c) {
         movingPiece.classList.remove(C.GetColorClass(apparentColor));
-        movingPiece.classList.add(C.GetColorClass(move.drag.c));
+        movingPiece.classList.add(C.GetColorClass(drag.c));
       }
     }
     container.appendChild(movingPiece);
     const animateSegment = (index, cb) => {
       // NOTE: move.drag could be generalized per-segment (usage?)
-      const [i1, j1] = move.segments[index][0];
-      const [i2, j2] = move.segments[index][1];
+      const [i1, j1] = segments[index][0];
+      const [i2, j2] = segments[index][1];
       const dep = this.getPixelPosition(i1, j1, r);
       const arr = this.getPixelPosition(i2, j2, r);
       movingPiece.style.transitionDuration = "0s";
@@ -2265,24 +2536,64 @@ export default class ChessRules {
         setTimeout(cb, duration * 1000);
       }, 50);
     };
-    if (!move.segments) {
-      move.segments = [
-        [[move.start.x, move.start.y], [move.end.x, move.end.y]]
-      ];
-    }
     let index = 0;
     const animateSegmentCallback = () => {
-      if (index < move.segments.length)
+      if (index < segments.length)
         animateSegment(index++, animateSegmentCallback);
       else {
         movingPiece.remove();
         initPiece.style.opacity = "1";
-        callback();
+        cb();
       }
     };
     animateSegmentCallback();
   }
 
+  // Input array of objects with at least fields x,y (e.g. PiPo)
+  animateFading(arr, cb) {
+    const animLength = 350; //TODO: 350ms? More? Less?
+    arr.forEach(v => {
+      let fadingPiece = this.getDomPiece(v.x, v.y);
+      fadingPiece.style.transitionDuration = (animLength / 1000) + "s";
+      fadingPiece.style.opacity = "0";
+    });
+    setTimeout(cb, animLength);
+  }
+
+  animate(move, callback) {
+    if (this.noAnimate || move.noAnimate) {
+      callback();
+      return;
+    }
+    let segments = move.segments;
+    if (!segments)
+      segments = [ [[move.start.x, move.start.y], [move.end.x, move.end.y]] ];
+    let targetObj = new TargetObj(callback);
+    if (move.start.x != move.end.x || move.start.y != move.end.y) {
+      targetObj.target++;
+      this.animateMoving(move.start, move.end, move.drag, segments,
+                         () => targetObj.increment());
+    }
+    if (move.vanish.length > move.appear.length) {
+      const arr = move.vanish.slice(move.appear.length)
+        // Ignore disappearing pieces hidden by some appearing ones:
+        .filter(v => move.appear.every(a => a.x != v.x || a.y != v.y));
+      if (arr.length > 0) {
+        targetObj.target++;
+        this.animateFading(arr, () => targetObj.increment());
+      }
+    }
+    targetObj.target +=
+      this.customAnimate(move, segments, () => targetObj.increment());
+    if (targetObj.target == 0)
+      callback();
+  }
+
+  // Potential other animations (e.g. for Suction variant)
+  customAnimate(move, segments, cb) {
+    return 0; //nb of targets
+  }
+
   playReceivedMove(moves, callback) {
     const launchAnimation = () => {
       const r = container.querySelector(".chessboard").getBoundingClientRect();