Retrieve faces from generated convex hull

Motivation:
- Generated convex hulls did not have connected faces, which is required for convex-convex collision in cannon-es
- Using the generated faces in ConvexHull addresses this
- Fixes donmccurdy#76

Author: isaac-mason

lib/ConvexHull.d.ts

@@ -1,4 +1,4 @@
-import { Mesh, Vector3 } from 'three';
+import { Vector3 } from 'three';
 
 declare class HalfEdge {
     next: HalfEdge;
@@ -12,5 +12,6 @@ declare class Face {
 
 declare class ConvexHull {
     public faces: Face[];
-    setFromObject(mesh: Mesh): this;
+    setFromPoints(points: Vector3[]): this;
+    collectFaces(): number[][];
 }

lib/ConvexHull.js

@@ -1,10 +1,10 @@
 import {
-	BufferGeometry,
 	Line3,
 	Plane,
 	Triangle,
 	Vector3
 } from 'three';
+
 /**
  * Ported from: https://github.com/maurizzzio/quickhull3d/ by Mauricio Poppe (https://github.com/maurizzzio)
  */
@@ -42,6 +42,18 @@ var ConvexHull = ( function () {
 
 	Object.assign( ConvexHull.prototype, {
 
+		collectFaces: function () {
+			const faceIndices = []
+			for (let i = 0; i < this.faces.length; i += 1) {
+				if (this.faces[i].mark !== Visible) {
+					throw Error('attempt to include a destroyed face in the hull');
+				}
+				const indices = this.faces[i].collectIndices();
+				faceIndices.push(indices);
+			}
+			return faceIndices;
+		},
+
 		setFromPoints: function ( points ) {
 
 			if ( Array.isArray( points ) !== true ) {
@@ -60,7 +72,7 @@ var ConvexHull = ( function () {
 
 			for ( var i = 0, l = points.length; i < l; i ++ ) {
 
-				this.vertices.push( new VertexNode( points[ i ] ) );
+				this.vertices.push( new VertexNode( points[ i ], i ) );
 
 			}
 
@@ -70,54 +82,6 @@ var ConvexHull = ( function () {
 
 		},
 
-		setFromObject: function ( object ) {
-
-			var points = [];
-
-			object.updateMatrixWorld( true );
-
-			object.traverse( function ( node ) {
-
-				var i, l, point;
-
-				var geometry = node.geometry;
-
-				if ( geometry === undefined ) return;
-
-				if ( geometry.isGeometry ) {
-
-					geometry = geometry.toBufferGeometry
-						? geometry.toBufferGeometry()
-						: new BufferGeometry().fromGeometry( geometry );
-
-				}
-
-				if ( geometry.isBufferGeometry ) {
-
-					var attribute = geometry.attributes.position;
-
-					if ( attribute !== undefined ) {
-
-						for ( i = 0, l = attribute.count; i < l; i ++ ) {
-
-							point = new Vector3();
-
-							point.fromBufferAttribute( attribute, i ).applyMatrix4( node.matrixWorld );
-
-							points.push( point );
-
-						}
-
-					}
-
-				}
-
-			} );
-
-			return this.setFromPoints( points );
-
-		},
-
 		containsPoint: function ( point ) {
 
 			var faces = this.faces;
@@ -980,6 +944,17 @@ var ConvexHull = ( function () {
 
 	Object.assign( Face.prototype, {
 
+		collectIndices: function () {
+			const indices = [];
+			let edge = this.edge;
+			console.log(this.edge)
+			do {
+				indices.push(edge.head().index);
+				edge = edge.next || null;
+			} while (edge !== this.edge);
+			return indices;
+		},
+
 		getEdge: function ( i ) {
 
 			var edge = this.edge;
@@ -1105,12 +1080,15 @@ var ConvexHull = ( function () {
 
 	// A vertex as a double linked list node.
 
-	function VertexNode( point ) {
+	function VertexNode( point, index ) {
 
 		this.point = point;
+		// index in the input array
+		this.index = index;
 		this.prev = null;
 		this.next = null;
-		this.face = null; // the face that is able to see this vertex
+		// the face that is able to see this vertex
+		this.face = null;
 
 	}
 

src/index.ts

@@ -1,6 +1,6 @@
-import { Box, Quaternion as CQuaternion, ConvexPolyhedron, Cylinder, Shape, Sphere, Trimesh, Vec3 } from 'cannon-es';
-import { Box3, BufferGeometry, CylinderGeometry, MathUtils, Mesh, Object3D, SphereGeometry, Vector3 } from 'three';
-import { ConvexHull } from '../lib/ConvexHull.js';
+import { Box, ConvexPolyhedron, Cylinder, Quaternion as CQuaternion, Shape, Sphere, Trimesh, Vec3 } from 'cannon-es';
+import { Box3, BufferGeometry, CylinderGeometry, MathUtils, Object3D, SphereGeometry, Vector3 } from 'three';
+import { ConvexHull } from '../lib/ConvexHull';
 import { getComponent, getGeometry, getVertices } from './utils';
 
 const PI_2 = Math.PI / 2;
@@ -254,34 +254,26 @@ function getConvexPolyhedronParameters (object: Object3D): ShapeParameters<Shape
 		);
 	}
 
-	// Compute the 3D convex hull.
-	const hull = new ConvexHull().setFromObject(new Mesh(geometry));
-	const hullFaces = hull.faces;
-	const vertices: number[] = [];
-	const faces: number[][] = [];
-
-	let currentFaceVertex = 0;
-	for (let i = 0; i < hullFaces.length; i++) {
-		const hullFace = hullFaces[ i ];
-		const face: number[] = [];
-		faces.push(face);
-
-		let edge = hullFace.edge;
-		do {
-			const point = edge.head().point;
-			vertices.push(point.x, point.y, point.z);
-			face.push(currentFaceVertex);
-			currentFaceVertex++;
-			edge = edge.next;
-		} while ( edge !== hullFace.edge );
+	// Get geometry points
+	const points: Vector3[] = []; 
+	for (let i = 0; i < geometry.attributes.position.array.length; i += 3) {
+		points.push(
+			new Vector3(
+				geometry.attributes.position.array[i],
+				geometry.attributes.position.array[i + 1],
+				geometry.attributes.position.array[i + 2]
+			)
+		);
 	}
 
-	const verticesTypedArray = new Float32Array(vertices.length);
-	verticesTypedArray.set(vertices);
+	// Get convex hull faces
+	const faces = new ConvexHull().setFromPoints(points).collectFaces();
+
+	const vertices = geometry.attributes.position.array as Float32Array
 
 	return {
 		type: ShapeType.HULL,
-		params: { vertices: verticesTypedArray, faces },
+		params: { vertices, faces },
 	};
 }