Make runIndex easier to use (#806)

* handled unsorted groups

* forgot types

bindings/wasm/examples/package.json

@@ -17,15 +17,15 @@
     "@gltf-transform/extensions": "^3.8.0",
     "@gltf-transform/functions": "^3.8.0",
     "@jscadui/3mf-export": "^0.5.0",
-    "@types/three": "^0.164.0",
     "fflate": "^0.8.0",
     "gl-matrix": "^3.4.3",
     "simple-dropzone": "0.8.3",
-    "three": "0.158.0"
+    "three": "0.164.1"
   },
   "devDependencies": {
     "@vitest/ui": "^0.31.1",
     "@vitest/web-worker": "^0.31.1",
+    "@types/three": "^0.164.0",
     "typescript": "5.2.2",
     "vite": "^4.5.0",
     "vitest": "^0.31.1"

bindings/wasm/examples/three.ts

@@ -64,8 +64,9 @@ cube.addGroup(18, Infinity, 1);  // Rest of faces are red
 
 const icosahedron = new IcosahedronGeometry(0.16);
 icosahedron.clearGroups();
+icosahedron.addGroup(30, Infinity, 2);  // Last faces are blue
 icosahedron.addGroup(0, 30, 0);         // First 10 faces colored by normal
-icosahedron.addGroup(30, Infinity, 2);  // Rest of faces are blue
+// The above groups are in reversed order to demonstrate the need for sorting.
 
 // Convert Three.js input meshes to Manifolds
 const manifoldCube = new Manifold(geometry2mesh(cube));
@@ -95,15 +96,18 @@ function geometry2mesh(geometry: BufferGeometry) {
   const triVerts = geometry.index != null ?
       geometry.index.array as Uint32Array :
       new Uint32Array(vertProperties.length / 3).map((_, idx) => idx);
-  // Create a triangle run for each group (material).
-  const runIndex =
-      new Uint32Array(geometry.groups.length + 1)
-          .map((_, idx) => geometry.groups[idx]?.start ?? triVerts.length);
-  // Map the materials to ID
-  const runOriginalID =
-      new Uint32Array(geometry.groups.length)
-          .map((_, idx) => ids[geometry.groups[idx].materialIndex!]);
-
+  // Create a triangle run for each group (material) - akin to a draw call.
+  const starts = [...Array(geometry.groups.length)].map(
+      (_, idx) => geometry.groups[idx].start);
+  // Map the materials to ID.
+  const originalIDs = [...Array(geometry.groups.length)].map(
+      (_, idx) => ids[geometry.groups[idx].materialIndex!]);
+  // List the runs in sequence.
+  const indices = Array.from(starts.keys())
+  indices.sort((a, b) => starts[a] - starts[b])
+  const runIndex = new Uint32Array(indices.map(i => starts[i]));
+  const runOriginalID = new Uint32Array(indices.map(i => originalIDs[i]));
+  // Create the MeshGL for I/O with Manifold library.
   const mesh =
       new Mesh({numProp: 3, vertProperties, triVerts, runIndex, runOriginalID});
   // Automatically merge vertices with nearly identical positions to create a

bindings/wasm/examples/tsconfig.json

@@ -2,7 +2,7 @@
   "compilerOptions": {
     "target": "es2022",
     "module": "es2022",
-    "moduleResolution": "node",
+    "moduleResolution": "Bundler",
     "lib": [
       "es2022",
       "dom"

bindings/wasm/examples/worker.test.js

@@ -17,7 +17,7 @@ import '@vitest/web-worker';
 import {WebIO} from '@gltf-transform/core';
 import {expect, suite, test} from 'vitest';
 
-import Module from './built/manifold.js';
+import Module from './built/manifold';
 import {readMesh, setupIO} from './gltf-io';
 import {examples} from './public/examples.js';
 import ManifoldWorker from './worker?worker';

src/manifold/include/manifold.h

@@ -77,7 +77,10 @@ struct MeshGL {
   /// Optional: Indicates runs of triangles that correspond to a particular
   /// input mesh instance. The runs encompass all of triVerts and are sorted
   /// by runOriginalID. Run i begins at triVerts[runIndex[i]] and ends at
-  /// triVerts[runIndex[i+1]]. All runIndex values are divisible by 3.
+  /// triVerts[runIndex[i+1]]. All runIndex values are divisible by 3. Returned
+  /// runIndex will always be 1 longer than runOriginalID, but same length is
+  /// also allowed as input: triVerts.size() will be automatically appended in
+  /// this case.
   std::vector<uint32_t> runIndex;
   /// Optional: The OriginalID of the mesh this triangle run came from. This ID
   /// is ideal for reapplying materials to the output mesh. Multiple runs may

src/manifold/src/impl.cpp

@@ -375,7 +375,8 @@ Manifold::Impl::Impl(const MeshGL& meshGL,
   }
 
   if (!meshGL.runOriginalID.empty() && !meshGL.runIndex.empty() &&
-      meshGL.runOriginalID.size() + 1 != meshGL.runIndex.size()) {
+      meshGL.runOriginalID.size() + 1 != meshGL.runIndex.size() &&
+      meshGL.runOriginalID.size() != meshGL.runIndex.size()) {
     MarkFailure(Error::RunIndexWrongLength);
     return;
   }
@@ -443,8 +444,11 @@ Manifold::Impl::Impl(const MeshGL& meshGL,
     relation.originalID = Impl::ReserveIDs(1);
   } else {
     std::vector<uint32_t> runIndex = meshGL.runIndex;
+    const uint32_t runEnd = meshGL.triVerts.size();
     if (runIndex.empty()) {
-      runIndex = {0, 3 * meshGL.NumTri()};
+      runIndex = {0, runEnd};
+    } else if (runIndex.size() == meshGL.runOriginalID.size()) {
+      runIndex.push_back(runEnd);
     }
     relation.triRef.resize(meshGL.NumTri());
     const int startID = Impl::ReserveIDs(meshGL.runOriginalID.size());