feat: scaffold mvp shell and content runtime

js/gameplay/difficulty/overlap-graph.js

@@ -0,0 +1,74 @@
+function getPieceArea(piece) {
+  return piece.width * piece.height
+}
+
+function overlapArea(left, right) {
+  const overlapWidth = Math.max(0, Math.min(left.x + left.width, right.x + right.width) - Math.max(left.x, right.x))
+  const overlapHeight = Math.max(0, Math.min(left.y + left.height, right.y + right.height) - Math.max(left.y, right.y))
+
+  return overlapWidth * overlapHeight
+}
+
+function overlapsCenterZone(lower, upper) {
+  const centerWidth = lower.width * 0.5
+  const centerHeight = lower.height * 0.5
+  const centerBox = {
+    x: lower.x + lower.width * 0.25,
+    y: lower.y + lower.height * 0.25,
+    width: centerWidth,
+    height: centerHeight,
+  }
+
+  return overlapArea(centerBox, upper) > 0
+}
+
+export function buildOverlapGraph(pieces) {
+  const graph = Object.fromEntries(pieces.map((piece) => [piece.id, []]))
+
+  for (let leftIndex = 0; leftIndex < pieces.length; leftIndex += 1) {
+    for (let rightIndex = 0; rightIndex < pieces.length; rightIndex += 1) {
+      if (leftIndex === rightIndex) {
+        continue
+      }
+
+      const blocker = pieces[leftIndex]
+      const blocked = pieces[rightIndex]
+
+      if (blocker.layer <= blocked.layer) {
+        continue
+      }
+
+      const ratio = overlapArea(blocker, blocked) / getPieceArea(blocked)
+
+      if (ratio >= 0.2 && overlapsCenterZone(blocked, blocker)) {
+        graph[blocker.id].push(blocked.id)
+      }
+    }
+  }
+
+  return graph
+}
+
+export function getClickablePieces(boardState) {
+  const pieces = (boardState.pieces ?? []).filter((piece) => !piece.removed)
+  const indegree = Object.fromEntries(pieces.map((piece) => [piece.id, 0]))
+  const graph = boardState.overlapGraph ?? {}
+
+  for (const blockedIds of Object.values(graph)) {
+    for (const blockedId of blockedIds) {
+      if (blockedId in indegree) {
+        indegree[blockedId] += 1
+      }
+    }
+  }
+
+  return pieces.filter((piece) => indegree[piece.id] === 0)
+}
+
+export function rebuildGraphAfterShuffle(boardState) {
+  return buildOverlapGraph(boardState.pieces ?? [])
+}
+
+export function rebuildGraphAfterUndo(boardState) {
+  return buildOverlapGraph(boardState.pieces ?? [])
+}