Trying to improve latency placing bombs while running

src/game.js

@@ -127,6 +127,7 @@ const network = {
   inputStateAtClient: {
     dir: null,
     bomb: false,
+    bombCell: null,
   },
   lastInputSentAt: 0,
   activeRoster: [],
@@ -712,7 +713,7 @@ function handleSocketMessage(raw) {
     if (!network.isHost || state.mode !== "multiplayer" || state.screen !== "game") {
       return;
     }
-    network.remoteInputs.set(msg.playerId, msg.input || { dir: null, bomb: false });
+    network.remoteInputs.set(msg.playerId, msg.input || { dir: null, bomb: false, bombCell: null });
     return;
   }
 
@@ -779,7 +780,7 @@ function leaveLobbyInternals() {
   network.activeRoster = [];
   state.notification.text = "";
   state.notification.expiresAt = 0;
-  network.inputStateAtClient = { dir: null, bomb: false };
+  network.inputStateAtClient = { dir: null, bomb: false, bombCell: null };
   network.lastInputSentAt = 0;
   network.hasReceivedSnapshot = false;
 }
@@ -975,22 +976,94 @@ function updateLobbyNetwork(dt) {
   }
 }
 
+function sameBombCell(a, b) {
+  if (!a && !b) {
+    return true;
+  }
+  if (!a || !b) {
+    return false;
+  }
+  return a.x === b.x && a.y === b.y;
+}
+
+function resolveBombDropCell(player, preferredCell = null) {
+  const candidates = [];
+  if (player.moveProgress < 1) {
+    candidates.push({ x: player.moveFromX, y: player.moveFromY });
+    if (player.moveToX !== player.moveFromX || player.moveToY !== player.moveFromY) {
+      candidates.push({ x: player.moveToX, y: player.moveToY });
+    }
+  } else {
+    candidates.push({ x: player.x, y: player.y });
+  }
+
+  const canPlaceAt = (x, y) => {
+    if (!inBounds(x, y)) {
+      return false;
+    }
+    const tile = state.map[y]?.[x];
+    if (!tile || tile.type !== "floor") {
+      return false;
+    }
+    return !getBombAt(x, y);
+  };
+
+  const isCandidateCell = (cell) =>
+    candidates.some((candidate) => candidate.x === cell.x && candidate.y === cell.y);
+
+  if (preferredCell && Number.isInteger(preferredCell.x) && Number.isInteger(preferredCell.y)) {
+    if (isCandidateCell(preferredCell) && canPlaceAt(preferredCell.x, preferredCell.y)) {
+      return { x: preferredCell.x, y: preferredCell.y };
+    }
+  }
+
+  const primary =
+    player.moveProgress < 1 && player.moveProgress >= 0.5
+      ? { x: player.moveToX, y: player.moveToY }
+      : candidates[0];
+
+  if (primary && canPlaceAt(primary.x, primary.y)) {
+    return { x: primary.x, y: primary.y };
+  }
+
+  for (const candidate of candidates) {
+    if (canPlaceAt(candidate.x, candidate.y)) {
+      return { x: candidate.x, y: candidate.y };
+    }
+  }
+
+  return null;
+}
+
 function sendLocalMultiplayerInput(force = false) {
   if (state.mode !== "multiplayer" || state.screen !== "game" || network.isHost) {
     return;
   }
   const t = now();
+  const localPlayer = state.players.find((player) => player.ownerId === network.clientId) || null;
   const nextInput = {
     dir: currentHumanDirection(),
     bomb: inputState.bombHeld,
+    bombCell: null,
   };
+  if (nextInput.bomb && localPlayer) {
+    nextInput.bombCell = resolveBombDropCell(localPlayer);
+  }
+
   const changed =
-    nextInput.dir !== network.inputStateAtClient.dir || nextInput.bomb !== network.inputStateAtClient.bomb;
+    nextInput.dir !== network.inputStateAtClient.dir ||
+    nextInput.bomb !== network.inputStateAtClient.bomb ||
+    !sameBombCell(nextInput.bombCell, network.inputStateAtClient.bombCell);
   const dueHeartbeat = t - network.lastInputSentAt > 0.12;
   if (!changed && !force && !dueHeartbeat) {
     return;
   }
-  network.inputStateAtClient = nextInput;
+
+  network.inputStateAtClient = {
+    dir: nextInput.dir,
+    bomb: nextInput.bomb,
+    bombCell: nextInput.bombCell ? { ...nextInput.bombCell } : null,
+  };
   network.lastInputSentAt = t;
   sendSocketMessage("player_input", { input: nextInput, ts: t });
 }
@@ -1032,18 +1105,20 @@ function queueDetonation(bombId) {
   state.pendingDetonations.push(bombId);
 }
 
-function dropBomb(player) {
+function dropBomb(player, preferredCell = null) {
   if (!player.alive || player.bombsPlaced >= player.bombCapacity) {
     return false;
   }
-  if (getBombAt(player.x, player.y)) {
+
+  const dropCell = resolveBombDropCell(player, preferredCell);
+  if (!dropCell) {
     return false;
   }
 
   const bomb = {
     id: state.nextBombId,
-    x: player.x,
-    y: player.y,
+    x: dropCell.x,
+    y: dropCell.y,
     timer: CONFIG.bombFuse,
     range: player.flameRange,
     ownerId: player.id,
@@ -1329,7 +1404,7 @@ function occupiedTiles(player) {
 }
 
 function getNetworkInput(ownerId) {
-  return network.remoteInputs.get(ownerId) || { dir: null, bomb: false };
+  return network.remoteInputs.get(ownerId) || { dir: null, bomb: false, bombCell: null };
 }
 
 function getDesiredDirection(player) {
@@ -1371,8 +1446,9 @@ function updatePlayerMovement(player, dt) {
     player.renderY = player.y;
   }
 
+  const occupied = new Set(occupiedTiles(player));
   for (const bomb of state.bombs) {
-    if (bomb.passThrough.has(player.id) && (player.x !== bomb.x || player.y !== bomb.y)) {
+    if (bomb.passThrough.has(player.id) && !occupied.has(tileKey(bomb.x, bomb.y))) {
       bomb.passThrough.delete(player.id);
     }
   }
@@ -1585,7 +1661,7 @@ function updateGame(dt) {
       const remote = getNetworkInput(player.ownerId);
       const prevBomb = network.remoteBombPrev.get(player.ownerId) || false;
       if (remote.bomb && !prevBomb) {
-        dropBomb(player);
+        dropBomb(player, remote.bombCell || null);
       }
       network.remoteBombPrev.set(player.ownerId, remote.bomb);
     }