Report renderer progress and detect stalled jobs

renderer/scene.js

@@ -162,9 +162,28 @@ window.buildTerrain = async (snapshot) => {
     unsupported = new Set();
   const occupancy = new Map();
   const distinctStates = new Set();
-  for (const b of snapshot.blocks) {
+  let lastProgress = 0;
+  async function progress(percent, message, force = false) {
+    if (!force && performance.now() - lastProgress < 3000) return;
+    lastProgress = performance.now();
+    // Yield to browser tasks so bindings, cancellation and timers can run.
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    await window.minegeoProgress?.({ percent, message });
+  }
+  await progress(
+    25,
+    `Indexing ${snapshot.blocks.length.toLocaleString()} terrain blocks`,
+    true,
+  );
+  for (let i = 0; i < snapshot.blocks.length; i++) {
+    const b = snapshot.blocks[i];
     occupancy.set(`${b[0]},${b[1]},${b[2]}`, b[3]);
     distinctStates.add(b[3]);
+    if (i % 16384 === 0)
+      await progress(
+        25 + (5 * i) / snapshot.blocks.length,
+        `Indexing blocks ${i}/${snapshot.blocks.length}`,
+      );
   }
   const stateCache = new Map();
   async function stateModels(s) {
@@ -182,8 +201,15 @@ window.buildTerrain = async (snapshot) => {
     return variants;
   }
   // Preload each distinct model once before constructing batched geometry.
-  for (const s of distinctStates)
+  await progress(30, "Loading block models and textures", true);
+  let modelCount = 0;
+  for (const s of distinctStates) {
     await stateModels(s);
+    await progress(
+      30 + (5 * ++modelCount) / distinctStates.size,
+      `Loading block model ${modelCount}/${distinctStates.size}`,
+    );
+  }
   async function emit(block, m, v = {}) {
     const [bx, by, bz, s] = block;
     for (const e of m.elements || []) {
@@ -284,7 +310,14 @@ window.buildTerrain = async (snapshot) => {
       }
     }
   }
-  for (const b of snapshot.blocks) {
+  await progress(35, "Building terrain geometry", true);
+  for (let i = 0; i < snapshot.blocks.length; i++) {
+    const b = snapshot.blocks[i];
+    if (i % 256 === 0)
+      await progress(
+        35 + (20 * i) / snapshot.blocks.length,
+        `Building blocks ${i}/${snapshot.blocks.length}`,
+      );
     if (/minecraft:(water|lava)(\[|$)/.test(b[3])) {
       await emit(b, {
         textures: {
@@ -314,6 +347,8 @@ window.buildTerrain = async (snapshot) => {
     for (const { m, v } of await stateModels(b[3])) await emit(b, m, v);
   }
   occupancy.clear();
+  await progress(55, "Preparing the scene", true);
+  let batchCount = 0;
   for (const batch of batches.values()) {
     const g = new THREE.BufferGeometry();
     g.setAttribute(
@@ -340,6 +375,10 @@ window.buildTerrain = async (snapshot) => {
     batch.normals.length = 0;
     batch.uvs.length = 0;
     batch.indices.length = 0;
+    await progress(
+      55 + (5 * ++batchCount) / batches.size,
+      `Preparing geometry ${batchCount}/${batches.size}`,
+    );
   }
   window.terrainBounds = snapshot.bounds;
   return {