X-Git-Url: https://git.auder.net/?a=blobdiff_plain;f=base_rules.js;h=6562673aeb3804f8fc7bfa494d6494d839769f98;hb=5f08c59b29c2173cc8b2df1a3799ee971a14e691;hp=4805f174b55773fc5e5a3e79dc9792d8a8b6dfaf;hpb=0c44c6768654f7127e36aa75beee58d61df4fc64;p=xogo.git

diff --git a/base_rules.js b/base_rules.js
index 4805f17..6562673 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 {
@@ -29,16 +44,18 @@ export default class ChessRules {
           {label: "Asymmetric random", value: 2}
         ]
       }],
-      check: [
+      input: [
         {
           label: "Capture king",
-          defaut: false,
-          variable: "taking"
+          variable: "taking",
+          type: "checkbox",
+          defaut: false
         },
         {
           label: "Falling pawn",
-          defaut: false,
-          variable: "pawnfall"
+          variable: "pawnfall",
+          type: "checkbox",
+          defaut: false
         }
       ],
       // Game modifiers (using "elementary variants"). Default: false
@@ -85,11 +102,19 @@ export default class ChessRules {
       (!!this.options["recycle"] && !this.options["teleport"])
     );
   }
+  // Some variants do not store reserve state (Align4, Chakart...)
+  get hasReserveFen() {
+    return this.hasReserve;
+  }
 
   get noAnimate() {
     return !!this.options["dark"];
   }
 
+  get hasMoveStack() {
+    return false;
+  }
+
   // Some variants use click infos:
   doClick(coords) {
     if (typeof coords.x != "number")
@@ -98,7 +123,7 @@ export default class ChessRules {
       this.options["teleport"] && this.subTurnTeleport == 2 &&
       this.board[coords.x][coords.y] == ""
     ) {
-      return new Move({
+      let res = new Move({
         start: {x: this.captured.x, y: this.captured.y},
         appear: [
           new PiPo({
@@ -108,9 +133,10 @@ export default class ChessRules {
             p: this.captured.p
           })
         ],
-        vanish: [],
-        drag: {c: this.captured.c, p: this.captured.p}
+        vanish: []
       });
+      res.drag = {c: this.captured.c, p: this.captured.p};
+      return res;
     }
     return null;
   }
@@ -172,8 +198,6 @@ export default class ChessRules {
 
   // Setup the initial random-or-not (asymmetric-or-not) position
   genRandInitFen(seed) {
-    Random.setSeed(seed);
-
     let fen, flags = "0707";
     if (!this.options.randomness)
       // Deterministic:
@@ -181,7 +205,8 @@ export default class ChessRules {
 
     else {
       // Randomize
-      let pieces = { w: new Array(8), b: new Array(8) };
+      Random.setSeed(seed);
+      let pieces = {w: new Array(8), b: new Array(8)};
       flags = "";
       // Shuffle pieces on first (and last rank if randomness == 2)
       for (let c of ["w", "b"]) {
@@ -246,7 +271,7 @@ export default class ChessRules {
       parts.push(`"flags":"${flags}"`);
     if (this.hasEnpassant)
       parts.push('"enpassant":"-"');
-    if (this.hasReserve)
+    if (this.hasReserveFen)
       parts.push('"reserve":"000000000000"');
     if (this.options["crazyhouse"])
       parts.push('"ispawn":"-"');
@@ -280,7 +305,7 @@ export default class ChessRules {
       parts.push(`"flags":"${this.getFlagsFen()}"`);
     if (this.hasEnpassant)
       parts.push(`"enpassant":"${this.getEnpassantFen()}"`);
-    if (this.hasReserve)
+    if (this.hasReserveFen)
       parts.push(`"reserve":"${this.getReserveFen()}"`);
     if (this.options["crazyhouse"])
       parts.push(`"ispawn":"${this.getIspawnFen()}"`);
@@ -289,19 +314,20 @@ export default class ChessRules {
     return fen;
   }
 
+  static FenEmptySquares(count) {
+    // if more than 9 consecutive free spaces, break the integer,
+    // otherwise FEN parsing will fail.
+    if (count <= 9)
+      return count;
+    // Most boards of size < 18:
+    if (count <= 18)
+      return "9" + (count - 9);
+    // Except Gomoku:
+    return "99" + (count - 18);
+  }
+
   // Position part of the FEN string
   getPosition() {
-    const format = (count) => {
-      // if more than 9 consecutive free spaces, break the integer,
-      // otherwise FEN parsing will fail.
-      if (count <= 9)
-        return count;
-      // Most boards of size < 18:
-      if (count <= 18)
-        return "9" + (count - 9);
-      // Except Gomoku:
-      return "99" + (count - 18);
-    };
     let position = "";
     for (let i = 0; i < this.size.y; i++) {
       let emptyCount = 0;
@@ -311,7 +337,7 @@ export default class ChessRules {
         else {
           if (emptyCount > 0) {
             // Add empty squares in-between
-            position += format(emptyCount);
+            position += C.FenEmptySquares(emptyCount);
             emptyCount = 0;
           }
           position += this.board2fen(this.board[i][j]);
@@ -319,7 +345,7 @@ export default class ChessRules {
       }
       if (emptyCount > 0)
         // "Flush remainder"
-        position += format(emptyCount);
+        position += C.FenEmptySquares(emptyCount);
       if (i < this.size.y - 1)
         position += "/"; //separate rows
     }
@@ -370,23 +396,35 @@ export default class ChessRules {
 
   constructor(o) {
     this.options = o.options;
+    // Fill missing options (always the case if random challenge)
+    (V.Options.select || []).concat(V.Options.input || []).forEach(opt => {
+      if (this.options[opt.variable] === undefined)
+        this.options[opt.variable] = opt.defaut;
+    });
+    if (o.genFenOnly)
+      // This object will be used only for initial FEN generation
+      return;
     this.playerColor = o.color;
     this.afterPlay = o.afterPlay; //trigger some actions after playing a move
 
     // Fen string fully describes the game state
     if (!o.fen)
       o.fen = this.genRandInitFen(o.seed);
-    const fenParsed = this.parseFen(o.fen);
-    this.board = this.getBoard(fenParsed.position);
-    this.turn = fenParsed.turn;
-    this.movesCount = parseInt(fenParsed.movesCount, 10);
-    this.setOtherVariables(fenParsed);
+    this.re_initFromFen(o.fen);
 
     // Graphical (can use variables defined above)
     this.containerId = o.element;
     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);
+  }
+
   // Turn position fen into double array ["wb","wp","bk",...]
   getBoard(position) {
     const rows = position.split("/");
@@ -418,7 +456,6 @@ export default class ChessRules {
       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;
@@ -428,6 +465,9 @@ 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() {
@@ -455,7 +495,7 @@ export default class ChessRules {
     const steps = this.pieces(this.playerColor)["p"].attack[0].steps;
     for (let step of steps) {
       const x = this.epSquare.x - step[0],
-            y = this.computeY(this.epSquare.y - step[1]);
+            y = this.getY(this.epSquare.y - step[1]);
       if (
         this.onBoard(x, y) &&
         this.getColor(x, y) == this.playerColor &&
@@ -519,6 +559,22 @@ export default class ChessRules {
     return `${this.containerId}|rnum-${color}${piece}`;
   }
 
+  static AddClass_es(piece, class_es) {
+    if (!Array.isArray(class_es))
+      class_es = [class_es];
+    class_es.forEach(cl => {
+      piece.classList.add(cl);
+    });
+  }
+
+  static RemoveClass_es(piece, class_es) {
+    if (!Array.isArray(class_es))
+      class_es = [class_es];
+    class_es.forEach(cl => {
+      piece.classList.remove(cl);
+    });
+  }
+
   graphicalInit() {
     // NOTE: not window.onresize = this.re_drawBoardElts because scope (this)
     window.onresize = () => this.re_drawBoardElements();
@@ -526,7 +582,6 @@ export default class ChessRules {
     this.initMouseEvents();
     const chessboard =
       document.getElementById(this.containerId).querySelector(".chessboard");
-    new ResizeObserver(this.rescale).observe(chessboard);
   }
 
   re_drawBoardElements() {
@@ -539,23 +594,24 @@ export default class ChessRules {
     // Compare window ratio width / height to aspectRatio:
     const windowRatio = window.innerWidth / window.innerHeight;
     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;
+      cbHeight = cbWidth / vRatio;
     }
     else {
       // Limiting dimension is height:
       cbHeight = Math.min(window.innerHeight, 767);
-      cbWidth = cbHeight * this.size.ratio;
+      cbWidth = cbHeight * vRatio;
     }
-    if (this.reserve) {
+    if (this.hasReserve) {
       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;
+        cbWidth = cbHeight * vRatio;
       }
     }
     chessboard.style.width = cbWidth + "px";
@@ -580,9 +636,8 @@ export default class ChessRules {
     const flipped = (this.playerColor == 'b');
     let board = `
       <svg
-        viewBox="0 0 80 80"
-        class="chessboard_SVG">
-      <g>`;
+        viewBox="0 0 ${10*this.size.y} ${10*this.size.x}"
+        class="chessboard_SVG">`;
     for (let i=0; i < this.size.x; i++) {
       for (let j=0; j < this.size.y; j++) {
         const ii = (flipped ? this.size.x - 1 - i : i);
@@ -591,16 +646,18 @@ export default class ChessRules {
         if (this.enlightened && !this.enlightened[ii][jj])
           classes += " in-shadow";
         // NOTE: x / y reversed because coordinates system is reversed.
-        board += `<rect
-          class="${classes}"
-          id="${this.coordsToId({x: ii, y: jj})}"
-          width="10"
-          height="10"
-          x="${10*j}"
-          y="${10*i}" />`;
+        board += `
+          <rect
+            class="${classes}"
+            id="${this.coordsToId({x: ii, y: jj})}"
+            width="10"
+            height="10"
+            x="${10*j}"
+            y="${10*i}"
+          />`;
       }
     }
-    board += "</g></svg>";
+    board += "</svg>";
     return board;
   }
 
@@ -634,49 +691,47 @@ export default class ChessRules {
           const color = this.getColor(i, j);
           const piece = this.getPiece(i, j);
           this.g_pieces[i][j] = document.createElement("piece");
-          this.g_pieces[i][j].classList.add(this.pieces()[piece]["class"]);
+          C.AddClass_es(this.g_pieces[i][j],
+                        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";
-          const [ip, jp] = this.getPixelPosition(i, j, r);
-          this.g_pieces[i][j].style.transform = `translate(${ip}px,${jp}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.reserve)
+    if (this.hasReserve)
       this.re_drawReserve(['w', 'b'], r);
   }
 
-  // NOTE: assume !!this.reserve
+  // NOTE: assume this.reserve != null
   re_drawReserve(colors, r) {
     if (this.r_pieces) {
       // Remove (old) reserve pieces
       for (let c of colors) {
-        if (!this.reserve[c])
-          continue;
-        Object.keys(this.reserve[c]).forEach(p => {
-          if (this.r_pieces[c][p]) {
-            this.r_pieces[c][p].remove();
-            delete this.r_pieces[c][p];
-            const numId = this.getReserveNumId(c, p);
-            document.getElementById(numId).remove();
-          }
+        Object.keys(this.r_pieces[c]).forEach(p => {
+          this.r_pieces[c][p].remove();
+          delete this.r_pieces[c][p];
+          const numId = this.getReserveNumId(c, p);
+          document.getElementById(numId).remove();
         });
-        let reservesDiv = document.getElementById("reserves_" + c);
-        if (reservesDiv)
-          reservesDiv.remove();
       }
     }
     else
-      this.r_pieces = { 'w': {}, 'b': {} };
-    let chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
+      this.r_pieces = { w: {}, b: {} };
+    let container = document.getElementById(this.containerId);
     if (!r)
-      r = chessboard.getBoundingClientRect();
+      r = container.querySelector(".chessboard").getBoundingClientRect();
     for (let c of colors) {
+      let reservesDiv = document.getElementById("reserves_" + c);
+      if (reservesDiv)
+        reservesDiv.remove();
       if (!this.reserve[c])
         continue;
       const nbR = this.getNbReservePieces(c);
@@ -694,7 +749,7 @@ export default class ChessRules {
       // NOTE: +1 fix display bug on Firefox at least
       rcontainer.style.width = (nbR * sqResSize + 1) + "px";
       rcontainer.style.height = sqResSize + "px";
-      chessboard.appendChild(rcontainer);
+      container.appendChild(rcontainer);
       for (let p of Object.keys(this.reserve[c])) {
         if (this.reserve[c][p] == 0)
           continue;
@@ -705,8 +760,7 @@ export default class ChessRules {
         r_cell.style.height = sqResSize + "px";
         rcontainer.appendChild(r_cell);
         let piece = document.createElement("piece");
-        const pieceSpec = this.pieces()[p];
-        piece.classList.add(pieceSpec["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%";
@@ -748,13 +802,13 @@ export default class ChessRules {
     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, 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, 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");
@@ -763,42 +817,49 @@ export default class ChessRules {
     }
   }
 
-  // After resize event: no need to destroy/recreate pieces
-  rescale() {
-    const container = document.getElementById(this.containerId);
-    if (!container)
-      return; //useful at initial loading
-    let chessboard = container.querySelector(".chessboard");
+  // Resize board: no need to destroy/recreate pieces
+  rescale(mode) {
+    let chessboard =
+      document.getElementById(this.containerId).querySelector(".chessboard");
     const r = chessboard.getBoundingClientRect();
-    const newRatio = r.width / r.height;
-    let newWidth = r.width,
-        newHeight = r.height;
-    if (newRatio > this.size.ratio) {
-      newWidth = r.height * this.size.ratio;
-      chessboard.style.width = newWidth + "px";
+    const multFact = (mode == "up" ? 1.05 : 0.95);
+    let [newWidth, newHeight] = [multFact * r.width, multFact * r.height];
+    // Stay in window:
+    const vRatio = this.size.ratio || 1;
+    if (newWidth > window.innerWidth) {
+      newWidth = window.innerWidth;
+      newHeight = newWidth / vRatio;
     }
-    else if (newRatio < this.size.ratio) {
-      newHeight = r.width / this.size.ratio;
-      chessboard.style.height = newHeight + "px";
+    if (newHeight > window.innerHeight) {
+      newHeight = window.innerHeight;
+      newWidth = newHeight * vRatio;
     }
+    chessboard.style.width = newWidth + "px";
+    chessboard.style.height = newHeight + "px";
     const newX = (window.innerWidth - newWidth) / 2;
     chessboard.style.left = newX + "px";
     const newY = (window.innerHeight - newHeight) / 2;
     chessboard.style.top = newY + "px";
-    const newR = { x: newX, y: newY, width: newWidth, height: newHeight };
+    const newR = {x: newX, y: newY, width: newWidth, height: newHeight};
     const pieceWidth = this.getPieceWidth(newWidth);
-    for (let i=0; i < this.size.x; i++) {
-      for (let j=0; j < this.size.y; j++) {
-        if (this.g_pieces[i][j]) {
-          // NOTE: could also use CSS transform "scale"
-          this.g_pieces[i][j].style.width = pieceWidth + "px";
-          this.g_pieces[i][j].style.height = pieceWidth + "px";
-          const [ip, jp] = this.getPixelPosition(i, j, newR);
-          this.g_pieces[i][j].style.transform = `translate(${ip}px,${jp}px)`;
+    // NOTE: next "if" for variants which use squares filling
+    // instead of "physical", moving pieces
+    if (this.g_pieces) {
+      for (let i=0; i < this.size.x; i++) {
+        for (let j=0; j < this.size.y; j++) {
+          if (this.g_pieces[i][j]) {
+            // NOTE: could also use CSS transform "scale"
+            this.g_pieces[i][j].style.width = pieceWidth + "px";
+            this.g_pieces[i][j].style.height = pieceWidth + "px";
+            const [ip, jp] = this.getPixelPosition(i, j, newR);
+            // Translate coordinates to use chessboard as reference:
+            this.g_pieces[i][j].style.transform =
+              `translate(${ip - newX}px,${jp - newY}px)`;
+          }
         }
       }
     }
-    if (this.reserve)
+    if (this.hasReserve)
       this.rescaleReserve(newR);
   }
 
@@ -830,7 +891,7 @@ export default class ChessRules {
     }
   }
 
-  // Return the absolute pixel coordinates (on board) given current position.
+  // Return the absolute pixel coordinates given current position.
   // Our coordinate system differs from CSS one (x <--> y).
   // We return here the CSS coordinates (more useful).
   getPixelPosition(i, j, r) {
@@ -850,12 +911,12 @@ export default class ChessRules {
       x = (flipped ? this.size.y - 1 - j : j) * sqSize;
       y = (flipped ? this.size.x - 1 - i : i) * sqSize;
     }
-    return [x, y];
+    return [r.x + x, r.y + y];
   }
 
   initMouseEvents() {
-    let chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
+    let container = document.getElementById(this.containerId);
+    let chessboard = container.querySelector(".chessboard");
 
     const getOffset = e => {
       if (e.clientX)
@@ -876,8 +937,8 @@ export default class ChessRules {
     const centerOnCursor = (piece, e) => {
       const centerShift = this.getPieceWidth(r.width) / 2;
       const offset = getOffset(e);
-      piece.style.left = (offset.x - r.x - centerShift) + "px";
-      piece.style.top = (offset.y - r.y - centerShift) + "px";
+      piece.style.left = (offset.x - centerShift) + "px";
+      piece.style.top = (offset.y - centerShift) + "px";
     }
 
     let start = null,
@@ -910,7 +971,7 @@ export default class ChessRules {
             curPiece.style.width = pieceWidth + "px";
             curPiece.style.height = pieceWidth + "px";
             centerOnCursor(curPiece, e);
-            chessboard.appendChild(curPiece);
+            container.appendChild(curPiece);
             startPiece.style.opacity = "0.4";
             chessboard.style.cursor = "none";
           }
@@ -929,11 +990,6 @@ export default class ChessRules {
     };
 
     const mouseup = (e) => {
-      const newR = chessboard.getBoundingClientRect();
-      if (newR.width != r.width || newR.height != r.height) {
-        this.rescale();
-        return;
-      }
       if (!start)
         return;
       const [x, y] = [start.x, start.y];
@@ -962,6 +1018,8 @@ export default class ChessRules {
       document.addEventListener("mousedown", mousedown);
       document.addEventListener("mousemove", mousemove);
       document.addEventListener("mouseup", mouseup);
+      document.addEventListener("wheel",
+        (e) => this.rescale(e.deltaY < 0 ? "up" : "down"));
     }
     if ('ontouchstart' in window) {
       // https://stackoverflow.com/a/42509310/12660887
@@ -977,6 +1035,8 @@ export default class ChessRules {
     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";
@@ -1002,8 +1062,9 @@ export default class ChessRules {
       choice.style.backgroundColor = "lightyellow";
       choice.onclick = () => callback(moves[i]);
       const piece = document.createElement("piece");
-      const pieceSpec = this.pieces()[moves[i].appear[0].p];
-      piece.classList.add(pieceSpec["class"]);
+      const cdisp = moves[i].choice || moves[i].appear[0].p;
+      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%";
@@ -1019,7 +1080,7 @@ export default class ChessRules {
     return {
       x: 8,
       y: 8,
-      ratio: 1 //for rectangular board = y / x
+      ratio: 1 //for rectangular board = y / x (optional, 1 = default)
     };
   }
 
@@ -1031,7 +1092,11 @@ export default class ChessRules {
   }
 
   static GetColorClass(c) {
-    return (c == 'w' ? "white" : "black");
+    if (c == 'w')
+      return "white";
+    if (c == 'b')
+      return "black";
+    return "other-color"; //unidentified color
   }
 
   // Assume square i,j isn't empty
@@ -1042,8 +1107,9 @@ export default class ChessRules {
   }
 
   // Piece type on square (i,j)
-  getPieceType(i, j) {
-    const p = (typeof i == "string" ? j : this.board[i][j].charAt(1));
+  getPieceType(i, j, p) {
+    if (!p)
+      p = this.getPiece(i, j);
     return C.CannibalKings[p] || p; //a cannibal king move as...
   }
 
@@ -1052,7 +1118,7 @@ export default class ChessRules {
     return (color == "w" ? "b" : "w");
   }
 
-  // Can thing on square1 capture (no return) thing on square2?
+  // Can thing on square1 capture (enemy) thing on square2?
   canTake([x1, y1], [x2, y2]) {
     return (this.getColor(x1, y1) !== this.getColor(x2, y2));
   }
@@ -1073,7 +1139,8 @@ export default class ChessRules {
 
   pieces(color, x, y) {
     const pawnShift = (color == "w" ? -1 : 1);
-    const initRank = ((color == 'w' && x == 6) || (color == 'b' && x == 1));
+    // NOTE: jump 2 squares from first rank (pawns can be here sometimes)
+    const initRank = ((color == 'w' && x >= 6) || (color == 'b' && x <= 1));
     return {
       'p': {
         "class": "pawn",
@@ -1155,7 +1222,7 @@ export default class ChessRules {
   // MOVES GENERATION
 
   // For Cylinder: get Y coordinate
-  computeY(y) {
+  getY(y) {
     if (!this.options["cylinder"])
       return y;
     let res = y % this.size.y;
@@ -1173,16 +1240,18 @@ export default class ChessRules {
         if (this.board[i][j] != "" && this.getColor(i, j) == color) {
           const allSpecs = this.pieces(color, i, j)
           let specs = allSpecs[this.getPieceType(i, j)];
+          if (specs.moveas)
+            specs = allSpecs[specs.moveas];
           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.computeY(j + step[1])];
+              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.computeY(jj + step[1]);
+                jj = this.getY(jj + step[1]);
               }
               if (
                 this.onBoard(ii, jj) &&
@@ -1203,7 +1272,7 @@ export default class ChessRules {
 
   getDropMovesFrom([c, p]) {
     // NOTE: by design, this.reserve[c][p] >= 1 on user click
-    // (but not necessarily otherwise)
+    // (but not necessarily otherwise: atLeastOneMove() etc)
     if (this.reserve[c][p] == 0)
       return [];
     let moves = [];
@@ -1283,7 +1352,7 @@ export default class ChessRules {
       this.options["rifle"]
     ) {
       // In this case a rifle-capture from last rank may promote a pawn
-      this.riflePromotePostProcess(moves);
+      this.riflePromotePostProcess(moves, color);
     }
 
     return moves;
@@ -1319,7 +1388,7 @@ export default class ChessRules {
         ];
         for (let step of steps) {
           let x = m.end.x + step[0];
-          let y = this.computeY(m.end.y + step[1]);
+          let y = this.getY(m.end.y + step[1]);
           if (
             this.onBoard(x, y) &&
             this.board[x][y] != "" &&
@@ -1384,7 +1453,7 @@ export default class ChessRules {
     Array.prototype.push.apply(moves, moreMoves);
   }
 
-  riflePromotePostProcess(moves) {
+  riflePromotePostProcess(moves, color) {
     const lastRank = (color == "w" ? 0 : this.size.x - 1);
     let newMoves = [];
     moves.forEach(m => {
@@ -1413,7 +1482,8 @@ export default class ChessRules {
       "#": "r",
       "$": "n",
       "%": "b",
-      "*": "q"
+      "*": "q",
+      "k": "k"
     };
   }
 
@@ -1429,10 +1499,7 @@ export default class ChessRules {
   }
 
   isKing(symbol) {
-    return (
-      symbol == 'k' ||
-      (this.options["cannibal"] && C.CannibalKings[symbol])
-    );
+    return !!C.CannibalKings[symbol];
   }
 
   // For Madrasi:
@@ -1443,7 +1510,10 @@ export default class ChessRules {
     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 allSpecs = this.pieces(color, x, y);
+    let stepSpec = allSpecs[piece];
+    if (stepSpec.moveas)
+      stepSpec = allSpecs[stepSpec.moveas];
     const attacks = stepSpec.attack || stepSpec.moves;
     for (let a of attacks) {
       outerLoop: for (let step of a.steps) {
@@ -1453,7 +1523,7 @@ export default class ChessRules {
           if (a.range <= stepCounter++)
             continue outerLoop;
           i += step[0];
-          j = this.computeY(j + step[1]);
+          j = this.getY(j + step[1]);
         }
         if (
           this.onBoard(i, j) &&
@@ -1467,28 +1537,63 @@ export default class ChessRules {
     return false;
   }
 
+  canStepOver(i, j, p) {
+    // In some variants, objects on boards don't stop movement (Chakart)
+    return this.board[i][j] == "";
+  }
+
   // 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];
+    const apparentPiece = this.getPiece(x, y); //how it looks
+    const allSpecs = this.pieces(color, x, y);
+    let stepSpec = allSpecs[piece];
+    if (stepSpec.moveas)
+      stepSpec = allSpecs[stepSpec.moveas];
     let moves = [];
-    let explored = {}; //for Cylinder mode
+    // Next 3 for Cylinder mode:
+    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 findAddMoves = (type, stepArray) => {
       for (let s of stepArray) {
-        // TODO: if jump in y (computeY, Cylinder), move.segments
         outerLoop: for (let step of s.steps) {
-          let [i, j] = [x + step[0], this.computeY(y + step[1])];
-          let stepCounter = 1;
-          while (this.onBoard(i, j) && this.board[i][j] == "") {
-            if (type != "attack" && !explored[i + "." + j]) {
+          segments = [];
+          segStart = [x, y];
+          let [i, j] = [x, y];
+          let stepCounter = 0;
+          while (
+            this.onBoard(i, j) &&
+            ((i == x && j == y) || this.canStepOver(i, j, apparentPiece))
+          ) {
+            if (
+              type != "attack" &&
+              !explored[i + "." + j] &&
+              (i != x || j != y)
+            ) {
               explored[i + "." + j] = true;
-              moves.push(this.getBasicMove([x, y], [i, j]));
+              addMove([x, y], [i, j]);
             }
             if (s.range <= stepCounter++)
               continue outerLoop;
+            const oldIJ = [i, j];
             i += step[0];
-            j = this.computeY(j + step[1]);
+            j = this.getY(j + step[1]);
+            if (Math.abs(j - oldIJ[1]) > 1) {
+              // Boundary between segments (cylinder mode)
+              segments.push([[segStart[0], segStart[1]], oldIJ]);
+              segStart = [i, j];
+            }
           }
           if (!this.onBoard(i, j))
             continue;
@@ -1509,7 +1614,7 @@ export default class ChessRules {
             )
           ) {
             explored[i + "." + j] = true;
-            moves.push(this.getBasicMove([x, y], [i, j]));
+            addMove([x, y], [i, j]);
           }
         }
       }
@@ -1519,28 +1624,35 @@ export default class ChessRules {
     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], true));
+    if (this.options["zen"]) {
+      Array.prototype.push.apply(moves,
+                                 this.findCapturesOn([x, y], {zen: true}));
+    }
     return moves;
   }
 
-  findCapturesOn([x, y], zen) {
+  // Search for enemy (or not) pieces attacking [x, y]
+  findCapturesOn([x, y], args) {
     let moves = [];
-    // Find reverse captures (opponent takes)
-    const color = this.getColor(x, y);
-    const pieceType = this.getPieceType(x, y);
-    const oppCol = C.GetOppCol(color);
+    if (!args.oppCol)
+      args.oppCol = C.GetOppCol(this.getColor(x, y) || 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.canTake([i, j], [x, y]) &&
+          this.getColor(i, j) == args.oppCol &&
           !this.isImmobilized([i, j])
         ) {
-          const piece = this.getPieceType(i, j);
-          if (zen && C.CannibalKingCode[piece])
+          if (args.zen && this.isKing(this.getPiece(i, j)))
             continue; //king not captured in this way
-          const stepSpec = this.pieces(oppCol, i, j)[piece];
+          const apparentPiece = this.getPiece(i, j);
+          // Quick check: does this potential attacker target x,y ?
+          if (this.canStepOver(x, y, apparentPiece))
+            continue;
+          const allSpecs = this.pieces(args.oppCol, i, j);
+          let stepSpec = allSpecs[this.getPieceType(i, j)];
+          if (stepSpec.moveas)
+            stepSpec = allSpecs[stepSpec.moveas];
           const attacks = stepSpec.attack || stepSpec.moves;
           for (let a of attacks) {
             for (let s of a.steps) {
@@ -1548,15 +1660,23 @@ export default class ChessRules {
               if (!C.CompatibleStep([i, j], [x, y], s, a.range))
                 continue;
               // Finally verify that nothing stand in-between
-              let [ii, jj] = [i + s[0], this.computeY(j + s[1])];
+              let [ii, jj] = [i + s[0], this.getY(j + s[1])];
               let stepCounter = 1;
-              while (this.onBoard(ii, jj) && this.board[ii][jj] == "") {
+              while (
+                this.onBoard(ii, jj) &&
+                this.board[ii][jj] == "" &&
+                (ii != x || jj != y) //condition to attack empty squares too
+              ) {
                 ii += s[0];
-                jj = this.computeY(jj + s[1]);
+                jj = this.getY(jj + s[1]);
               }
               if (ii == x && jj == y) {
-                moves.push(this.getBasicMove([x, y], [i, j]));
-                if (!zen)
+                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
               }
             }
@@ -1675,8 +1795,15 @@ 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,
@@ -1695,7 +1822,7 @@ export default class ChessRules {
     if (
       !!this.epSquare &&
       this.epSquare.x == x + shiftX &&
-      Math.abs(this.computeY(this.epSquare.y - y)) == 1 &&
+      Math.abs(this.getY(this.epSquare.y - y)) == 1 &&
       this.getColor(x, this.epSquare.y) == oppCol //Doublemove guard...
     ) {
       const [epx, epy] = [this.epSquare.x, this.epSquare.y];
@@ -1813,11 +1940,13 @@ export default class ChessRules {
   ////////////////////
   // MOVES VALIDATION
 
-  // Is (king at) given position under check by "color" ?
-  underCheck([x, y], color) {
+  // Is (king at) given position under check by "oppCol" ?
+  underCheck([x, y], oppCol) {
     if (this.options["taking"] || this.options["dark"])
       return false;
-    return (this.findCapturesOn([x, y]).length >= 1);
+    return (
+      this.findCapturesOn([x, y], {oppCol: oppCol, one: true}).length >= 1
+    );
   }
 
   // Stop at first king found (TODO: multi-kings)
@@ -1831,10 +1960,12 @@ export default class ChessRules {
     return [-1, -1]; //king not found
   }
 
-  filterValid(moves) {
+  // Some variants (e.g. Refusal) may need to check opponent moves too
+  filterValid(moves, color) {
     if (moves.length == 0)
       return [];
-    const color = this.turn;
+    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:
@@ -1862,12 +1993,12 @@ export default class ChessRules {
         let square = kingPos,
             res = true; //a priori valid
         if (m.vanish.some(v => {
-          return (v.p == "k" || C.CannibalKings[v.p]) && v.c == color;
+          return this.isKing(v.p) && v.c == color;
         })) {
           // Search king in appear array:
           const newKingIdx =
             m.appear.findIndex(a => {
-              return (a.p == "k" || C.CannibalKings[a.p]) && a.c == color;
+              return this.isKing(a.p) && a.c == color;
             });
           if (newKingIdx >= 0)
             square = [m.appear[newKingIdx].x, m.appear[newKingIdx].y];
@@ -1898,13 +2029,17 @@ export default class ChessRules {
 
   // Apply a move on board
   playOnBoard(move) {
-    for (let psq of move.vanish) this.board[psq.x][psq.y] = "";
-    for (let psq of move.appear) this.board[psq.x][psq.y] = psq.c + psq.p;
+    for (let psq of move.vanish)
+      this.board[psq.x][psq.y] = "";
+    for (let psq of move.appear)
+      this.board[psq.x][psq.y] = psq.c + psq.p;
   }
   // Un-apply the played move
   undoOnBoard(move) {
-    for (let psq of move.appear) this.board[psq.x][psq.y] = "";
-    for (let psq of move.vanish) this.board[psq.x][psq.y] = psq.c + psq.p;
+    for (let psq of move.appear)
+      this.board[psq.x][psq.y] = "";
+    for (let psq of move.vanish)
+      this.board[psq.x][psq.y] = psq.c + psq.p;
   }
 
   updateCastleFlags(move) {
@@ -2018,35 +2153,38 @@ 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["doublemove"] &&
-          this.movesCount >= 1 &&
-          this.subTurn == 1
-        ) ||
-        (this.options["progressive"] && this.subTurn <= this.movesCount)
+          this.options["taking"] ||
+          !this.underCheck(oppKingPos, color)
+        )
       ) {
-        const oppKingPos = this.searchKingPos(oppCol);
-        if (
-          oppKingPos[0] >= 0 &&
-          (
-            this.options["taking"] ||
-            !this.underCheck(oppKingPos, color)
-          )
-        ) {
-          this.subTurn++;
-          return;
-        }
+        this.subTurn++;
+        return;
       }
+    }
+    if (this.isLastMove(move)) {
       this.turn = oppCol;
+      this.movesCount++;
+      this.subTurn = 1;
     }
-    this.movesCount++;
-    this.subTurn = 1;
+  }
+
+  isLastMove(move) {
+    return (
+      (this.options["balance"] && ![1, 3].includes(this.movesCount)) ||
+      !move.next
+    );
   }
 
   // "Stop at the first move found"
@@ -2093,12 +2231,9 @@ export default class ChessRules {
     return (color == "w" ? "0-1" : "1-0");
   }
 
-  // NOTE: quite suboptimal for eg. Benedict (not a big deal I think)
   playVisual(move, r) {
     move.vanish.forEach(v => {
-      // TODO: next "if" shouldn't be required
-      if (this.g_pieces[v.x][v.y])
-        this.g_pieces[v.x][v.y].remove();
+      this.g_pieces[v.x][v.y].remove();
       this.g_pieces[v.x][v.y] = null;
     });
     let chessboard =
@@ -2108,12 +2243,15 @@ export default class ChessRules {
     const pieceWidth = this.getPieceWidth(r.width);
     move.appear.forEach(a => {
       this.g_pieces[a.x][a.y] = document.createElement("piece");
-      this.g_pieces[a.x][a.y].classList.add(this.pieces()[a.p]["class"]);
-      this.g_pieces[a.x][a.y].classList.add(a.c == "w" ? "white" : "black");
+      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";
       const [ip, jp] = this.getPixelPosition(a.x, a.y, r);
-      this.g_pieces[a.x][a.y].style.transform = `translate(${ip}px,${jp}px)`;
+      // Translate coordinates to use chessboard as reference:
+      this.g_pieces[a.x][a.y].style.transform =
+        `translate(${ip - r.x}px,${jp - r.y}px)`;
       if (this.enlightened && !this.enlightened[a.x][a.y])
         this.g_pieces[a.x][a.y].classList.add("hidden");
       chessboard.appendChild(this.g_pieces[a.x][a.y]);
@@ -2123,85 +2261,162 @@ export default class ChessRules {
   }
 
   playPlusVisual(move, r) {
+    if (this.hasMoveStack)
+      this.buildMoveStack(move);
+    else {
+      this.play(move);
+      this.playVisual(move, r);
+      this.afterPlay(move, this.turn, {send: true, res: true}); //user method
+    }
+  }
+
+  // TODO: send stack receive stack, or allow incremental? (good/bad points)
+  buildMoveStack(move) {
+    this.moveStack.push(move);
+    this.computeNextMove(move);
     this.play(move);
-    this.playVisual(move, r);
-    this.afterPlay(move); //user method
+    const newTurn = this.turn;
+    if (this.moveStack.length == 1) {
+      this.playVisual(move);
+      this.gameState = {
+        fen: this.getFen(),
+        board: JSON.parse(JSON.stringify(this.board)) //easier
+      };
+    }
+    if (move.next)
+      this.buildMoveStack(move.next);
+    else {
+      // Send, animate + play until here
+      if (this.moveStack.length == 1) {
+        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 = []
+        });
+      }
+    }
   }
 
-  getMaxDistance(rwidth) {
+  // Implemented in variants using (automatic) moveStack
+  computeNextMove(move) {}
+
+  getMaxDistance(r) {
     // Works for all rectangular boards:
-    return Math.sqrt(rwidth ** 2 + (rwidth / this.size.ratio) ** 2);
+    return Math.sqrt(r.width ** 2 + r.height ** 2);
   }
 
   getDomPiece(x, y) {
     return (typeof x == "string" ? this.r_pieces : this.g_pieces)[x][y];
   }
 
-  animate(move, callback) {
-    if (this.noAnimate || move.noAnimate) {
-      callback();
-      return;
+  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 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";
     }
-    let movingPiece = this.getDomPiece(move.start.x, move.start.y);
-    if (!movingPiece) { //TODO this shouldn't be required
-      callback();
-      return;
-    }
-    const initTransform = movingPiece.style.transform;
-    let chessboard =
-      document.getElementById(this.containerId).querySelector(".chessboard");
-    const r = chessboard.getBoundingClientRect();
-    const [ix, iy] = this.getPixelPosition(move.start.x, move.start.y, r);
-    const maxDist = this.getMaxDistance(r.width);
-    // NOTE: move.drag could be generalized per-segment (usage?)
-    if (move.drag) {
-      // Drag something else: require cloning
-      movingPiece = movingPiece.cloneNode();
-      const pieces = this.pieces();
-      const startCode = this.getPiece(move.start.x, move.start.y);
-      movingPiece.classList.remove(pieces[startCode]["class"]);
-      movingPiece.classList.add(pieces[move.drag.p]["class"]);
-      const apparentColor = this.getColor(move.start.x, move.start.y);
-      if (apparentColor != move.drag.c) {
+    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[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));
       }
-      chessboard.appendChild(movingPiece);
     }
+    container.appendChild(movingPiece);
     const animateSegment = (index, cb) => {
-      const [i1, j1] = move.segments[index][0];
-      const [i2, j2] = move.segments[index][1];
+      // NOTE: move.drag could be generalized per-segment (usage?)
+      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";
+      movingPiece.style.transform = `translate(${dep[0]}px, ${dep[1]}px)`;
       const distance =
         Math.sqrt((arr[0] - dep[0]) ** 2 + (arr[1] - dep[1]) ** 2);
       const duration = 0.2 + (distance / maxDist) * 0.3;
-      movingPiece.style.transform = `translate(${arr[0]}px, ${arr[1]}px)`;
-      movingPiece.style.transitionDuration = duration + "s";
-      setTimeout(cb, duration * 1000);
+      // TODO: unclear why we need this new delay below:
+      setTimeout(() => {
+        movingPiece.style.transitionDuration = duration + "s";
+        // movingPiece is child of container: no need to adjust coordinates
+        movingPiece.style.transform = `translate(${arr[0]}px, ${arr[1]}px)`;
+        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 {
-        if (move.drag)
-          movingPiece.remove();
-        else {
-          movingPiece.style.transform = initTransform;
-          movingPiece.style.transitionDuration = "0s";
-        }
-        callback();
+        movingPiece.remove();
+        initPiece.style.opacity = "1";
+        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)
+                    .filter(v => v.x != move.end.x || v.y != move.end.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();