ConvexPolyhedrons and Compound Shapes
Video Lecture
Description
In this video I will demonstrate several different methods of creating collision boundaries, also sometimes called collision meshes, using various ConvexPolyhedrons and Compound Shapes. I will also compare the performance and differences between them.
When positioning the parts of a compound shape, you can use a 3d graphics tool to help estimate the positioning. It is is important to know though, that if you use Blender, then be aware that Blender, by default, uses a different coordinate system. In Blender, Z is UP, and the Y axis is used for Near/Far and it is also negative compared to Threejs. So you will need to swap around the coordinates for Y and Z and negate the new Z.
To position an object from the perspective of a default Threejs camera looking down the Z axis, with UP axis [0,1,0], see table for conversion.
Axis | Threejs | Blender |
---|---|---|
Up/Down | Y / -Y | Z / -Z |
Left/Right | -X / X | -X / X |
Near/Far | Z / -Z | -Y / Y |
Eg, If the 3D coordinates in Blender are [1,2,3], then in Threejs, the equivalent is [1,3,-2]
Start Scripts
./src/server/server.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | import express from "express" import path from "path" import http from "http" const port: number = 3000 class App { private server: http.Server private port: number constructor(port: number) { this.port = port const app = express() app.use(express.static(path.join(__dirname, '../client'))) app.use('/build/three.module.js', express.static(path.join(__dirname, '../../node_modules/three/build/three.module.js'))) app.use('/jsm/controls/OrbitControls', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/controls/OrbitControls.js'))) app.use('/jsm/libs/stats.module', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/libs/stats.module.js'))) app.use('/jsm/libs/dat.gui.module', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/libs/dat.gui.module.js'))) app.use('/jsm/loaders/OBJLoader', express.static(path.join(__dirname, '../../node_modules/three/examples/jsm/loaders/OBJLoader.js'))) app.use('/cannon/cannon.min', express.static(path.join(__dirname, '../../node_modules/cannon/build/cannon.js'))) this.server = new http.Server(app); } public Start() { this.server.listen(this.port, () => { console.log( `Server listening on port ${this.port}.` ) }) } } new App(port).Start() |
./src/client/client.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 | import * as THREE from '/build/three.module.js' import { OrbitControls } from '/jsm/controls/OrbitControls' import Stats from '/jsm/libs/stats.module' import { GUI } from '/jsm/libs/dat.gui.module' import '/cannon/cannon.min' import CannonDebugRenderer from './utils/cannonDebugRenderer.js' import CannonUtils from './utils/cannonUtils.js' import { OBJLoader } from '/jsm/loaders/OBJLoader' const scene: THREE.Scene = new THREE.Scene() const axesHelper = new THREE.AxesHelper(5) scene.add(axesHelper) var light1 = new THREE.SpotLight(); light1.position.set(2.5, 5, 5) light1.angle = Math.PI / 4 light1.penumbra = 0.5 light1.castShadow = true; light1.shadow.mapSize.width = 1024; light1.shadow.mapSize.height = 1024; light1.shadow.camera.near = 0.5; light1.shadow.camera.far = 20 scene.add(light1); var light2 = new THREE.SpotLight(); light2.position.set(-2.5, 5, 5) light2.angle = Math.PI / 4 light2.penumbra = 0.5 light2.castShadow = true; light2.shadow.mapSize.width = 1024; light2.shadow.mapSize.height = 1024; light2.shadow.camera.near = 0.5; light2.shadow.camera.far = 20 scene.add(light2); const camera: THREE.PerspectiveCamera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000) const renderer: THREE.WebGLRenderer = new THREE.WebGLRenderer() renderer.setSize(window.innerWidth, window.innerHeight) renderer.shadowMap.enabled = true renderer.shadowMap.type = THREE.PCFSoftShadowMap document.body.appendChild(renderer.domElement) const controls = new OrbitControls(camera, renderer.domElement) controls.screenSpacePanning = true const world = new CANNON.World() world.gravity.set(0, -9.82, 0) //world.broadphase = new CANNON.NaiveBroadphase() // //world.solver.iterations = 10 //world.allowSleep = true const normalMaterial: THREE.MeshNormalMaterial = new THREE.MeshNormalMaterial() const phongMaterial: THREE.MeshPhongMaterial = new THREE.MeshPhongMaterial() let monkeyMeshes: THREE.Object3D[] = new Array() let monkeyBodies: CANNON.Body[] = new Array() let monkeyLoaded: Boolean = false const objLoader: OBJLoader = new OBJLoader(); objLoader.load( 'models/monkey.obj', //'models/monkeyPhysics.obj', (object) => { //scene.add(object) const monkeyMesh = object.children[0]; (monkeyMesh as THREE.Mesh).material = normalMaterial // let monkeyMesh: THREE.Object3D // let monkeyCollisionMesh: THREE.Object3D // object.traverse(function (child) { // console.log(child.name) // if (child.name === "Suzanne") { // monkeyMesh = child; // (monkeyMesh as THREE.Mesh).material = normalMaterial // } else if (child.name.startsWith("physics")) { // monkeyCollisionMesh = child; // } // }) for (let i = 0; i < 10; i++) { const monkeyMeshClone = monkeyMesh.clone() monkeyMeshClone.position.x = Math.floor(Math.random() * 10) - 5 monkeyMeshClone.position.z = Math.floor(Math.random() * 10) - 5 monkeyMeshClone.position.y = 5 + i scene.add(monkeyMeshClone) monkeyMeshes.push(monkeyMeshClone) const monkeyShape = CannonUtils.CreateTrimesh((monkeyMesh as THREE.Mesh).geometry) //const monkeyShape = CannonUtils.CreateConvexPolyhedron(new THREE.IcosahedronGeometry(1)) //const monkeyShape = CannonUtils.CreateConvexPolyhedron((monkeyMesh as THREE.Mesh).geometry) //const monkeyShape = CannonUtils.CreateConvexPolyhedron((monkeyCollisionMesh as THREE.Mesh).geometry) const monkeyBody = new CANNON.Body({ mass: 1 }); monkeyBody.addShape(monkeyShape) // monkeyBody.addShape(new CANNON.Sphere(.8), new CANNON.Vec3(0, .2, 0))// head, // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(0, -.97, 0.46))// chin, // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(-1.36, .29, -0.5)) //left ear // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(1.36, .29, -0.5)) //right ear // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(0, .56, -0.85)) //head top // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(0, .98, -0.07)) //forehead top monkeyBody.position.x = monkeyMeshClone.position.x monkeyBody.position.y = monkeyMeshClone.position.y monkeyBody.position.z = monkeyMeshClone.position.z world.addBody(monkeyBody) monkeyBodies.push(monkeyBody) } monkeyLoaded = true }, (xhr) => { console.log((xhr.loaded / xhr.total * 100) + '% loaded'); }, (error) => { console.log('An error happened'); } ); const planeGeometry: THREE.PlaneGeometry = new THREE.PlaneGeometry(25, 25) const planeMesh: THREE.Mesh = new THREE.Mesh(planeGeometry, phongMaterial) planeMesh.rotateX(-Math.PI / 2) planeMesh.receiveShadow = true; scene.add(planeMesh) const planeShape = new CANNON.Plane() const planeBody = new CANNON.Body({ mass: 0 }) planeBody.addShape(planeShape) planeBody.quaternion.setFromAxisAngle(new CANNON.Vec3(1, 0, 0), -Math.PI / 2) world.addBody(planeBody) camera.position.y = 4 camera.position.z = 4 controls.target.y = 2 window.addEventListener('resize', onWindowResize, false) function onWindowResize() { camera.aspect = window.innerWidth / window.innerHeight camera.updateProjectionMatrix() renderer.setSize(window.innerWidth, window.innerHeight) render() } const stats = Stats() document.body.appendChild(stats.dom) const gui = new GUI() const physicsFolder = gui.addFolder("Physics") physicsFolder.add(world.gravity, "x", -10.0, 10.0, 0.1) physicsFolder.add(world.gravity, "y", -10.0, 10.0, 0.1) physicsFolder.add(world.gravity, "z", -10.0, 10.0, 0.1) physicsFolder.open() const clock: THREE.Clock = new THREE.Clock() const cannonDebugRenderer = new CannonDebugRenderer(scene, world) var animate = function () { requestAnimationFrame(animate) controls.update() let delta = clock.getDelta() if (delta > .1) delta = .1 world.step(delta) cannonDebugRenderer.update() // Copy coordinates from Cannon.js to Three.js if (monkeyLoaded) { monkeyMeshes.forEach((m, i) => { m.position.set(monkeyBodies[i].position.x, monkeyBodies[i].position.y, monkeyBodies[i].position.z); m.quaternion.set(monkeyBodies[i].quaternion.x, monkeyBodies[i].quaternion.y, monkeyBodies[i].quaternion.z, monkeyBodies[i].quaternion.w); }) } render() stats.update() }; function render() { renderer.render(scene, camera) } animate(); |
./src/client/utils/cannonUtils.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | import * as THREE from '/build/three.module.js' class CannonUtils { constructor() { } public static CreateTrimesh(geometry: THREE.Geometry | THREE.BufferGeometry): CANNON.Trimesh { if (!(geometry as THREE.BufferGeometry).attributes) { geometry = new THREE.BufferGeometry().fromGeometry(geometry as THREE.Geometry); } const vertices: number[] = <number[]>(geometry as THREE.BufferGeometry).attributes.position.array const indices: number[] = Object.keys(vertices).map(Number); return new CANNON.Trimesh(vertices, indices); } public static CreateConvexPolyhedron(geometry: THREE.Geometry | THREE.BufferGeometry): CANNON.ConvexPolyhedron { if (!(geometry as THREE.Geometry).vertices) { geometry = new THREE.Geometry().fromBufferGeometry(geometry as THREE.BufferGeometry); geometry.mergeVertices() geometry.computeBoundingSphere(); geometry.computeFaceNormals(); } const points: CANNON.Vec3[] = (<THREE.Geometry>geometry).vertices.map(function (v) { return new CANNON.Vec3(v.x, v.y, v.z) }) const faces: number[][] = (<THREE.Geometry>geometry).faces.map(function (f) { return [f.a, f.b, f.c] }) return new CANNON.ConvexPolyhedron(points, faces); } public static offsetCenterOfMass(body: CANNON.Body, centreOfMass: CANNON.Vec3) { body.shapeOffsets.forEach(function (offset) { centreOfMass.vadd(offset, centreOfMass) }) centreOfMass.scale(1 / body.shapes.length, centreOfMass) body.shapeOffsets.forEach(function (offset) { offset.vsub(centreOfMass, offset) }) const worldCenterOfMass = new CANNON.Vec3() body.vectorToWorldFrame(centreOfMass, worldCenterOfMass) body.position.vadd(worldCenterOfMass, body.position) } } export default CannonUtils; |
Final Script
./src/client/client.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 | import * as THREE from '/build/three.module.js' import { OrbitControls } from '/jsm/controls/OrbitControls' import Stats from '/jsm/libs/stats.module' import { GUI } from '/jsm/libs/dat.gui.module' import '/cannon/cannon.min' import CannonDebugRenderer from './utils/cannonDebugRenderer.js' import CannonUtils from './utils/cannonUtils.js' import { OBJLoader } from '/jsm/loaders/OBJLoader' const scene: THREE.Scene = new THREE.Scene() const axesHelper = new THREE.AxesHelper(5) scene.add(axesHelper) var light1 = new THREE.SpotLight(); light1.position.set(2.5, 5, 5) light1.angle = Math.PI / 4 light1.penumbra = 0.5 light1.castShadow = true; light1.shadow.mapSize.width = 1024; light1.shadow.mapSize.height = 1024; light1.shadow.camera.near = 0.5; light1.shadow.camera.far = 20 scene.add(light1); var light2 = new THREE.SpotLight(); light2.position.set(-2.5, 5, 5) light2.angle = Math.PI / 4 light2.penumbra = 0.5 light2.castShadow = true; light2.shadow.mapSize.width = 1024; light2.shadow.mapSize.height = 1024; light2.shadow.camera.near = 0.5; light2.shadow.camera.far = 20 scene.add(light2); const camera: THREE.PerspectiveCamera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000) const renderer: THREE.WebGLRenderer = new THREE.WebGLRenderer() renderer.setSize(window.innerWidth, window.innerHeight) renderer.shadowMap.enabled = true renderer.shadowMap.type = THREE.PCFSoftShadowMap document.body.appendChild(renderer.domElement) const controls = new OrbitControls(camera, renderer.domElement) controls.screenSpacePanning = true const world = new CANNON.World() world.gravity.set(0, -9.82, 0) //world.broadphase = new CANNON.NaiveBroadphase() // //world.solver.iterations = 10 //world.allowSleep = true const normalMaterial: THREE.MeshNormalMaterial = new THREE.MeshNormalMaterial() const phongMaterial: THREE.MeshPhongMaterial = new THREE.MeshPhongMaterial() let monkeyMeshes: THREE.Object3D[] = new Array() let monkeyBodies: CANNON.Body[] = new Array() let monkeyLoaded: Boolean = false const objLoader: OBJLoader = new OBJLoader(); objLoader.load( 'models/monkey.obj', //'models/monkeyPhysics.obj', (object) => { //scene.add(object) const monkeyMesh = object.children[0]; (monkeyMesh as THREE.Mesh).material = normalMaterial; (<THREE.MeshNormalMaterial>(<THREE.Mesh>monkeyMesh).material).flatShading = true // let monkeyMesh: THREE.Object3D // let monkeyCollisionMesh: THREE.Object3D // object.traverse(function (child) { // console.log(child.name) // if (child.name === "Suzanne") { // monkeyMesh = child; // (monkeyMesh as THREE.Mesh).material = normalMaterial // } else if (child.name.startsWith("physics")) { // monkeyCollisionMesh = child; // } // }) for (let i = 0; i < 200; i++) { const monkeyMeshClone = monkeyMesh.clone() monkeyMeshClone.position.x = Math.floor(Math.random() * 10) - 5 monkeyMeshClone.position.z = Math.floor(Math.random() * 10) - 5 monkeyMeshClone.position.y = 5 + i scene.add(monkeyMeshClone) monkeyMeshes.push(monkeyMeshClone) //const monkeyShape = CannonUtils.CreateTrimesh((monkeyMesh as THREE.Mesh).geometry) //const monkeyShape = CannonUtils.CreateConvexPolyhedron(new THREE.IcosahedronGeometry(1)) //const monkeyShape = CannonUtils.CreateConvexPolyhedron((monkeyMesh as THREE.Mesh).geometry) //const monkeyShape = CannonUtils.CreateConvexPolyhedron((monkeyCollisionMesh as THREE.Mesh).geometry) const monkeyBody = new CANNON.Body({ mass: 1 }); //monkeyBody.addShape(monkeyShape) monkeyBody.addShape(new CANNON.Sphere(.8), new CANNON.Vec3(0, .2, 0))// head, monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(0, -.97, 0.46))// chin, monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(-1.36, .29, -0.5)) //left ear monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(1.36, .29, -0.5)) //right ear // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(0, .56, -0.85)) //head top // monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(0, .98, -0.07)) //forehead top monkeyBody.addShape(new CANNON.Sphere(.05), new CANNON.Vec3(-.32, .75, 0.73)) //left eyebrow top monkeyBody.position.x = monkeyMeshClone.position.x monkeyBody.position.y = monkeyMeshClone.position.y monkeyBody.position.z = monkeyMeshClone.position.z world.addBody(monkeyBody) monkeyBodies.push(monkeyBody) } monkeyLoaded = true }, (xhr) => { console.log((xhr.loaded / xhr.total * 100) + '% loaded'); }, (error) => { console.log('An error happened'); } ); const planeGeometry: THREE.PlaneGeometry = new THREE.PlaneGeometry(25, 25) const planeMesh: THREE.Mesh = new THREE.Mesh(planeGeometry, phongMaterial) planeMesh.rotateX(-Math.PI / 2) planeMesh.receiveShadow = true; scene.add(planeMesh) const planeShape = new CANNON.Plane() const planeBody = new CANNON.Body({ mass: 0 }) planeBody.addShape(planeShape) planeBody.quaternion.setFromAxisAngle(new CANNON.Vec3(1, 0, 0), -Math.PI / 2) world.addBody(planeBody) camera.position.y = 4 camera.position.z = 4 controls.target.y = 2 window.addEventListener('resize', onWindowResize, false) function onWindowResize() { camera.aspect = window.innerWidth / window.innerHeight camera.updateProjectionMatrix() renderer.setSize(window.innerWidth, window.innerHeight) render() } const stats = Stats() document.body.appendChild(stats.dom) const gui = new GUI() const physicsFolder = gui.addFolder("Physics") physicsFolder.add(world.gravity, "x", -10.0, 10.0, 0.1) physicsFolder.add(world.gravity, "y", -10.0, 10.0, 0.1) physicsFolder.add(world.gravity, "z", -10.0, 10.0, 0.1) physicsFolder.open() const clock: THREE.Clock = new THREE.Clock() const cannonDebugRenderer = new CannonDebugRenderer(scene, world) var animate = function () { requestAnimationFrame(animate) controls.update() let delta = clock.getDelta() if (delta > .1) delta = .1 world.step(delta) cannonDebugRenderer.update() // Copy coordinates from Cannon.js to Three.js if (monkeyLoaded) { monkeyMeshes.forEach((m, i) => { m.position.set(monkeyBodies[i].position.x, monkeyBodies[i].position.y, monkeyBodies[i].position.z); m.quaternion.set(monkeyBodies[i].quaternion.x, monkeyBodies[i].quaternion.y, monkeyBodies[i].quaternion.z, monkeyBodies[i].quaternion.w); }) } render() stats.update() }; function render() { renderer.render(scene, camera) } animate(); |