feat: scaffold mvp shell and content runtime

js/gameplay/difficulty/anchors.js

@@ -0,0 +1,55 @@
+const BOUNDS = {
+  left: 32,
+  right: 358,
+  top: 130,
+  bottom: 560,
+}
+
+export function createAnchorGrid(columns = 6, rows = 8) {
+  const anchors = []
+  const width = BOUNDS.right - BOUNDS.left
+  const height = BOUNDS.bottom - BOUNDS.top
+  const stepX = width / (columns - 1)
+  const stepY = height / (rows - 1)
+
+  for (let row = 0; row < rows; row += 1) {
+    for (let column = 0; column < columns; column += 1) {
+      anchors.push({
+        id: `anchor_${row}_${column}`,
+        x: BOUNDS.left + column * stepX,
+        y: BOUNDS.top + row * stepY,
+      })
+    }
+  }
+
+  return anchors
+}
+
+export function getLayerDistribution(density, layers) {
+  const presets = {
+    low: [0.4, 0.35, 0.25],
+    medium: [0.3, 0.3, 0.25, 0.15],
+    medium_high: [0.28, 0.27, 0.25, 0.2],
+    high: [0.25, 0.25, 0.25, 0.25],
+  }
+  const base = presets[density] ?? presets.medium
+  const sliced = base.slice(0, layers)
+  const total = sliced.reduce((sum, value) => sum + value, 0)
+
+  return sliced.map((value) => value / total)
+}
+
+export function allocateLayerCounts(totalPieces, density, layers) {
+  const distribution = getLayerDistribution(density, layers)
+  const counts = distribution.map((value) => Math.floor(totalPieces * value))
+  let assigned = counts.reduce((sum, value) => sum + value, 0)
+
+  while (assigned < totalPieces) {
+    for (let index = 0; index < counts.length && assigned < totalPieces; index += 1) {
+      counts[index] += 1
+      assigned += 1
+    }
+  }
+
+  return counts
+}