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physics_ammo_volume.html
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<html lang="en">
<head>
<title>Ammo.js softbody volume demo</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
<link type="text/css" rel="stylesheet" href="main.css">
<style>
body {
color: #333;
}
</style>
</head>
<body>
<div id="info">
Ammo.js physics soft body volume demo<br/>
Click to throw a ball
</div>
<div id="container"></div>
<script src="js/libs/ammo.wasm.js"></script>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/[email protected]/dist/es-module-shims.js"></script>
<script type="importmap">
{
"imports": {
"three": "../build/three.module.js",
"three/addons/": "./jsm/"
}
}
</script>
<script type="module">
import * as THREE from 'three';
import Stats from 'three/addons/libs/stats.module.js';
import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
import * as BufferGeometryUtils from 'three/addons/utils/BufferGeometryUtils.js';
// Graphics variables
let container, stats;
let camera, controls, scene, renderer;
let textureLoader;
const clock = new THREE.Clock();
let clickRequest = false;
const mouseCoords = new THREE.Vector2();
const raycaster = new THREE.Raycaster();
const ballMaterial = new THREE.MeshPhongMaterial( { color: 0x202020 } );
const pos = new THREE.Vector3();
const quat = new THREE.Quaternion();
// Physics variables
const gravityConstant = - 9.8;
let physicsWorld;
const rigidBodies = [];
const softBodies = [];
const margin = 0.05;
let transformAux1;
let softBodyHelpers;
Ammo().then( function ( AmmoLib ) {
Ammo = AmmoLib;
init();
animate();
} );
function init() {
initGraphics();
initPhysics();
createObjects();
initInput();
}
function initGraphics() {
container = document.getElementById( 'container' );
camera = new THREE.PerspectiveCamera( 60, window.innerWidth / window.innerHeight, 0.2, 2000 );
scene = new THREE.Scene();
scene.background = new THREE.Color( 0xbfd1e5 );
camera.position.set( - 7, 5, 8 );
renderer = new THREE.WebGLRenderer();
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
renderer.shadowMap.enabled = true;
container.appendChild( renderer.domElement );
controls = new OrbitControls( camera, renderer.domElement );
controls.target.set( 0, 2, 0 );
controls.update();
textureLoader = new THREE.TextureLoader();
const ambientLight = new THREE.AmbientLight( 0x404040 );
scene.add( ambientLight );
const light = new THREE.DirectionalLight( 0xffffff, 1 );
light.position.set( - 10, 10, 5 );
light.castShadow = true;
const d = 20;
light.shadow.camera.left = - d;
light.shadow.camera.right = d;
light.shadow.camera.top = d;
light.shadow.camera.bottom = - d;
light.shadow.camera.near = 2;
light.shadow.camera.far = 50;
light.shadow.mapSize.x = 1024;
light.shadow.mapSize.y = 1024;
scene.add( light );
stats = new Stats();
stats.domElement.style.position = 'absolute';
stats.domElement.style.top = '0px';
container.appendChild( stats.domElement );
window.addEventListener( 'resize', onWindowResize );
}
function initPhysics() {
// Physics configuration
const collisionConfiguration = new Ammo.btSoftBodyRigidBodyCollisionConfiguration();
const dispatcher = new Ammo.btCollisionDispatcher( collisionConfiguration );
const broadphase = new Ammo.btDbvtBroadphase();
const solver = new Ammo.btSequentialImpulseConstraintSolver();
const softBodySolver = new Ammo.btDefaultSoftBodySolver();
physicsWorld = new Ammo.btSoftRigidDynamicsWorld( dispatcher, broadphase, solver, collisionConfiguration, softBodySolver );
physicsWorld.setGravity( new Ammo.btVector3( 0, gravityConstant, 0 ) );
physicsWorld.getWorldInfo().set_m_gravity( new Ammo.btVector3( 0, gravityConstant, 0 ) );
transformAux1 = new Ammo.btTransform();
softBodyHelpers = new Ammo.btSoftBodyHelpers();
}
function createObjects() {
// Ground
pos.set( 0, - 0.5, 0 );
quat.set( 0, 0, 0, 1 );
const ground = createParalellepiped( 40, 1, 40, 0, pos, quat, new THREE.MeshPhongMaterial( { color: 0xFFFFFF } ) );
ground.castShadow = true;
ground.receiveShadow = true;
textureLoader.load( 'textures/grid.png', function ( texture ) {
texture.wrapS = THREE.RepeatWrapping;
texture.wrapT = THREE.RepeatWrapping;
texture.repeat.set( 40, 40 );
ground.material.map = texture;
ground.material.needsUpdate = true;
} );
// Create soft volumes
const volumeMass = 15;
const sphereGeometry = new THREE.SphereGeometry( 1.5, 40, 25 );
sphereGeometry.translate( 5, 5, 0 );
createSoftVolume( sphereGeometry, volumeMass, 250 );
const boxGeometry = new THREE.BoxGeometry( 1, 1, 5, 4, 4, 20 );
boxGeometry.translate( - 2, 5, 0 );
createSoftVolume( boxGeometry, volumeMass, 120 );
// Ramp
pos.set( 3, 1, 0 );
quat.setFromAxisAngle( new THREE.Vector3( 0, 0, 1 ), 30 * Math.PI / 180 );
const obstacle = createParalellepiped( 10, 1, 4, 0, pos, quat, new THREE.MeshPhongMaterial( { color: 0x606060 } ) );
obstacle.castShadow = true;
obstacle.receiveShadow = true;
}
function processGeometry( bufGeometry ) {
// Ony consider the position values when merging the vertices
const posOnlyBufGeometry = new THREE.BufferGeometry();
posOnlyBufGeometry.setAttribute( 'position', bufGeometry.getAttribute( 'position' ) );
posOnlyBufGeometry.setIndex( bufGeometry.getIndex() );
// Merge the vertices so the triangle soup is converted to indexed triangles
const indexedBufferGeom = BufferGeometryUtils.mergeVertices( posOnlyBufGeometry );
// Create index arrays mapping the indexed vertices to bufGeometry vertices
mapIndices( bufGeometry, indexedBufferGeom );
}
function isEqual( x1, y1, z1, x2, y2, z2 ) {
const delta = 0.000001;
return Math.abs( x2 - x1 ) < delta &&
Math.abs( y2 - y1 ) < delta &&
Math.abs( z2 - z1 ) < delta;
}
function mapIndices( bufGeometry, indexedBufferGeom ) {
// Creates ammoVertices, ammoIndices and ammoIndexAssociation in bufGeometry
const vertices = bufGeometry.attributes.position.array;
const idxVertices = indexedBufferGeom.attributes.position.array;
const indices = indexedBufferGeom.index.array;
const numIdxVertices = idxVertices.length / 3;
const numVertices = vertices.length / 3;
bufGeometry.ammoVertices = idxVertices;
bufGeometry.ammoIndices = indices;
bufGeometry.ammoIndexAssociation = [];
for ( let i = 0; i < numIdxVertices; i ++ ) {
const association = [];
bufGeometry.ammoIndexAssociation.push( association );
const i3 = i * 3;
for ( let j = 0; j < numVertices; j ++ ) {
const j3 = j * 3;
if ( isEqual( idxVertices[ i3 ], idxVertices[ i3 + 1 ], idxVertices[ i3 + 2 ],
vertices[ j3 ], vertices[ j3 + 1 ], vertices[ j3 + 2 ] ) ) {
association.push( j3 );
}
}
}
}
function createSoftVolume( bufferGeom, mass, pressure ) {
processGeometry( bufferGeom );
const volume = new THREE.Mesh( bufferGeom, new THREE.MeshPhongMaterial( { color: 0xFFFFFF } ) );
volume.castShadow = true;
volume.receiveShadow = true;
volume.frustumCulled = false;
scene.add( volume );
textureLoader.load( 'textures/colors.png', function ( texture ) {
volume.material.map = texture;
volume.material.needsUpdate = true;
} );
// Volume physic object
const volumeSoftBody = softBodyHelpers.CreateFromTriMesh(
physicsWorld.getWorldInfo(),
bufferGeom.ammoVertices,
bufferGeom.ammoIndices,
bufferGeom.ammoIndices.length / 3,
true );
const sbConfig = volumeSoftBody.get_m_cfg();
sbConfig.set_viterations( 40 );
sbConfig.set_piterations( 40 );
// Soft-soft and soft-rigid collisions
sbConfig.set_collisions( 0x11 );
// Friction
sbConfig.set_kDF( 0.1 );
// Damping
sbConfig.set_kDP( 0.01 );
// Pressure
sbConfig.set_kPR( pressure );
// Stiffness
volumeSoftBody.get_m_materials().at( 0 ).set_m_kLST( 0.9 );
volumeSoftBody.get_m_materials().at( 0 ).set_m_kAST( 0.9 );
volumeSoftBody.setTotalMass( mass, false );
Ammo.castObject( volumeSoftBody, Ammo.btCollisionObject ).getCollisionShape().setMargin( margin );
physicsWorld.addSoftBody( volumeSoftBody, 1, - 1 );
volume.userData.physicsBody = volumeSoftBody;
// Disable deactivation
volumeSoftBody.setActivationState( 4 );
softBodies.push( volume );
}
function createParalellepiped( sx, sy, sz, mass, pos, quat, material ) {
const threeObject = new THREE.Mesh( new THREE.BoxGeometry( sx, sy, sz, 1, 1, 1 ), material );
const shape = new Ammo.btBoxShape( new Ammo.btVector3( sx * 0.5, sy * 0.5, sz * 0.5 ) );
shape.setMargin( margin );
createRigidBody( threeObject, shape, mass, pos, quat );
return threeObject;
}
function createRigidBody( threeObject, physicsShape, mass, pos, quat ) {
threeObject.position.copy( pos );
threeObject.quaternion.copy( quat );
const transform = new Ammo.btTransform();
transform.setIdentity();
transform.setOrigin( new Ammo.btVector3( pos.x, pos.y, pos.z ) );
transform.setRotation( new Ammo.btQuaternion( quat.x, quat.y, quat.z, quat.w ) );
const motionState = new Ammo.btDefaultMotionState( transform );
const localInertia = new Ammo.btVector3( 0, 0, 0 );
physicsShape.calculateLocalInertia( mass, localInertia );
const rbInfo = new Ammo.btRigidBodyConstructionInfo( mass, motionState, physicsShape, localInertia );
const body = new Ammo.btRigidBody( rbInfo );
threeObject.userData.physicsBody = body;
scene.add( threeObject );
if ( mass > 0 ) {
rigidBodies.push( threeObject );
// Disable deactivation
body.setActivationState( 4 );
}
physicsWorld.addRigidBody( body );
return body;
}
function initInput() {
window.addEventListener( 'pointerdown', function ( event ) {
if ( ! clickRequest ) {
mouseCoords.set(
( event.clientX / window.innerWidth ) * 2 - 1,
- ( event.clientY / window.innerHeight ) * 2 + 1
);
clickRequest = true;
}
} );
}
function processClick() {
if ( clickRequest ) {
raycaster.setFromCamera( mouseCoords, camera );
// Creates a ball
const ballMass = 3;
const ballRadius = 0.4;
const ball = new THREE.Mesh( new THREE.SphereGeometry( ballRadius, 18, 16 ), ballMaterial );
ball.castShadow = true;
ball.receiveShadow = true;
const ballShape = new Ammo.btSphereShape( ballRadius );
ballShape.setMargin( margin );
pos.copy( raycaster.ray.direction );
pos.add( raycaster.ray.origin );
quat.set( 0, 0, 0, 1 );
const ballBody = createRigidBody( ball, ballShape, ballMass, pos, quat );
ballBody.setFriction( 0.5 );
pos.copy( raycaster.ray.direction );
pos.multiplyScalar( 14 );
ballBody.setLinearVelocity( new Ammo.btVector3( pos.x, pos.y, pos.z ) );
clickRequest = false;
}
}
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
function animate() {
requestAnimationFrame( animate );
render();
stats.update();
}
function render() {
const deltaTime = clock.getDelta();
updatePhysics( deltaTime );
processClick();
renderer.render( scene, camera );
}
function updatePhysics( deltaTime ) {
// Step world
physicsWorld.stepSimulation( deltaTime, 10 );
// Update soft volumes
for ( let i = 0, il = softBodies.length; i < il; i ++ ) {
const volume = softBodies[ i ];
const geometry = volume.geometry;
const softBody = volume.userData.physicsBody;
const volumePositions = geometry.attributes.position.array;
const volumeNormals = geometry.attributes.normal.array;
const association = geometry.ammoIndexAssociation;
const numVerts = association.length;
const nodes = softBody.get_m_nodes();
for ( let j = 0; j < numVerts; j ++ ) {
const node = nodes.at( j );
const nodePos = node.get_m_x();
const x = nodePos.x();
const y = nodePos.y();
const z = nodePos.z();
const nodeNormal = node.get_m_n();
const nx = nodeNormal.x();
const ny = nodeNormal.y();
const nz = nodeNormal.z();
const assocVertex = association[ j ];
for ( let k = 0, kl = assocVertex.length; k < kl; k ++ ) {
let indexVertex = assocVertex[ k ];
volumePositions[ indexVertex ] = x;
volumeNormals[ indexVertex ] = nx;
indexVertex ++;
volumePositions[ indexVertex ] = y;
volumeNormals[ indexVertex ] = ny;
indexVertex ++;
volumePositions[ indexVertex ] = z;
volumeNormals[ indexVertex ] = nz;
}
}
geometry.attributes.position.needsUpdate = true;
geometry.attributes.normal.needsUpdate = true;
}
// Update rigid bodies
for ( let i = 0, il = rigidBodies.length; i < il; i ++ ) {
const objThree = rigidBodies[ i ];
const objPhys = objThree.userData.physicsBody;
const ms = objPhys.getMotionState();
if ( ms ) {
ms.getWorldTransform( transformAux1 );
const p = transformAux1.getOrigin();
const q = transformAux1.getRotation();
objThree.position.set( p.x(), p.y(), p.z() );
objThree.quaternion.set( q.x(), q.y(), q.z(), q.w() );
}
}
}
</script>
</body>
</html>