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<html lang="en">
<head>
<title>Amjs softbody rope 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 rope demo<br>Press Q or A to move the arm.</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/es-module-shims@1.3.6/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';
// Graphics variables
let container, stats;
let camera, controls, scene, renderer;
let textureLoader;
const clock = new THREE.Clock();
// Physics variables
const gravityConstant = - 9.8;
let collisionConfiguration;
let dispatcher;
let broadphase;
let solver;
let softBodySolver;
let physicsWorld;
const rigidBodies = [];
const margin = 0.05;
let hinge;
let rope;
let transformAux1;
let armMovement = 0;
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 = 10;
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
collisionConfiguration = new Ammo.btSoftBodyRigidBodyCollisionConfiguration();
dispatcher = new Ammo.btCollisionDispatcher( collisionConfiguration );
broadphase = new Ammo.btDbvtBroadphase();
solver = new Ammo.btSequentialImpulseConstraintSolver();
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();
}
function createObjects() {
const pos = new THREE.Vector3();
const quat = new THREE.Quaternion();
// 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;
} );
// Ball
const ballMass = 1.2;
const ballRadius = 0.6;
const ball = new THREE.Mesh( new THREE.SphereGeometry( ballRadius, 20, 20 ), new THREE.MeshPhongMaterial( { color: 0x202020 } ) );
ball.castShadow = true;
ball.receiveShadow = true;
const ballShape = new Ammo.btSphereShape( ballRadius );
ballShape.setMargin( margin );
pos.set( - 3, 2, 0 );
quat.set( 0, 0, 0, 1 );
createRigidBody( ball, ballShape, ballMass, pos, quat );
ball.userData.physicsBody.setFriction( 0.5 );
// Wall
const brickMass = 0.5;
const brickLength = 1.2;
const brickDepth = 0.6;
const brickHeight = brickLength * 0.5;
const numBricksLength = 6;
const numBricksHeight = 8;
const z0 = - numBricksLength * brickLength * 0.5;
pos.set( 0, brickHeight * 0.5, z0 );
quat.set( 0, 0, 0, 1 );
for ( let j = 0; j < numBricksHeight; j ++ ) {
const oddRow = ( j % 2 ) == 1;
pos.z = z0;
if ( oddRow ) {
pos.z -= 0.25 * brickLength;
}
const nRow = oddRow ? numBricksLength + 1 : numBricksLength;
for ( let i = 0; i < nRow; i ++ ) {
let brickLengthCurrent = brickLength;
let brickMassCurrent = brickMass;
if ( oddRow && ( i == 0 || i == nRow - 1 ) ) {
brickLengthCurrent *= 0.5;
brickMassCurrent *= 0.5;
}
const brick = createParalellepiped( brickDepth, brickHeight, brickLengthCurrent, brickMassCurrent, pos, quat, createMaterial() );
brick.castShadow = true;
brick.receiveShadow = true;
if ( oddRow && ( i == 0 || i == nRow - 2 ) ) {
pos.z += 0.75 * brickLength;
} else {
pos.z += brickLength;
}
}
pos.y += brickHeight;
}
// The rope
// Rope graphic object
const ropeNumSegments = 10;
const ropeLength = 4;
const ropeMass = 3;
const ropePos = ball.position.clone();
ropePos.y += ballRadius;
const segmentLength = ropeLength / ropeNumSegments;
const ropeGeometry = new THREE.BufferGeometry();
const ropeMaterial = new THREE.LineBasicMaterial( { color: 0x000000 } );
const ropePositions = [];
const ropeIndices = [];
for ( let i = 0; i < ropeNumSegments + 1; i ++ ) {
ropePositions.push( ropePos.x, ropePos.y + i * segmentLength, ropePos.z );
}
for ( let i = 0; i < ropeNumSegments; i ++ ) {
ropeIndices.push( i, i + 1 );
}
ropeGeometry.setIndex( new THREE.BufferAttribute( new Uint16Array( ropeIndices ), 1 ) );
ropeGeometry.setAttribute( 'position', new THREE.BufferAttribute( new Float32Array( ropePositions ), 3 ) );
ropeGeometry.computeBoundingSphere();
rope = new THREE.LineSegments( ropeGeometry, ropeMaterial );
rope.castShadow = true;
rope.receiveShadow = true;
scene.add( rope );
// Rope physic object
const softBodyHelpers = new Ammo.btSoftBodyHelpers();
const ropeStart = new Ammo.btVector3( ropePos.x, ropePos.y, ropePos.z );
const ropeEnd = new Ammo.btVector3( ropePos.x, ropePos.y + ropeLength, ropePos.z );
const ropeSoftBody = softBodyHelpers.CreateRope( physicsWorld.getWorldInfo(), ropeStart, ropeEnd, ropeNumSegments - 1, 0 );
const sbConfig = ropeSoftBody.get_m_cfg();
sbConfig.set_viterations( 10 );
sbConfig.set_piterations( 10 );
ropeSoftBody.setTotalMass( ropeMass, false );
Ammo.castObject( ropeSoftBody, Ammo.btCollisionObject ).getCollisionShape().setMargin( margin * 3 );
physicsWorld.addSoftBody( ropeSoftBody, 1, - 1 );
rope.userData.physicsBody = ropeSoftBody;
// Disable deactivation
ropeSoftBody.setActivationState( 4 );
// The base
const armMass = 2;
const armLength = 3;
const pylonHeight = ropePos.y + ropeLength;
const baseMaterial = new THREE.MeshPhongMaterial( { color: 0x606060 } );
pos.set( ropePos.x, 0.1, ropePos.z - armLength );
quat.set( 0, 0, 0, 1 );
const base = createParalellepiped( 1, 0.2, 1, 0, pos, quat, baseMaterial );
base.castShadow = true;
base.receiveShadow = true;
pos.set( ropePos.x, 0.5 * pylonHeight, ropePos.z - armLength );
const pylon = createParalellepiped( 0.4, pylonHeight, 0.4, 0, pos, quat, baseMaterial );
pylon.castShadow = true;
pylon.receiveShadow = true;
pos.set( ropePos.x, pylonHeight + 0.2, ropePos.z - 0.5 * armLength );
const arm = createParalellepiped( 0.4, 0.4, armLength + 0.4, armMass, pos, quat, baseMaterial );
arm.castShadow = true;
arm.receiveShadow = true;
// Glue the rope extremes to the ball and the arm
const influence = 1;
ropeSoftBody.appendAnchor( 0, ball.userData.physicsBody, true, influence );
ropeSoftBody.appendAnchor( ropeNumSegments, arm.userData.physicsBody, true, influence );
// Hinge constraint to move the arm
const pivotA = new Ammo.btVector3( 0, pylonHeight * 0.5, 0 );
const pivotB = new Ammo.btVector3( 0, - 0.2, - armLength * 0.5 );
const axis = new Ammo.btVector3( 0, 1, 0 );
hinge = new Ammo.btHingeConstraint( pylon.userData.physicsBody, arm.userData.physicsBody, pivotA, pivotB, axis, axis, true );
physicsWorld.addConstraint( hinge, true );
}
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 );
}
function createRandomColor() {
return Math.floor( Math.random() * ( 1 << 24 ) );
}
function createMaterial() {
return new THREE.MeshPhongMaterial( { color: createRandomColor() } );
}
function initInput() {
window.addEventListener( 'keydown', function ( event ) {
switch ( event.keyCode ) {
// Q
case 81:
armMovement = 1;
break;
// A
case 65:
armMovement = - 1;
break;
}
} );
window.addEventListener( 'keyup', function () {
armMovement = 0;
} );
}
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 );
renderer.render( scene, camera );
}
function updatePhysics( deltaTime ) {
// Hinge control
hinge.enableAngularMotor( true, 1.5 * armMovement, 50 );
// Step world
physicsWorld.stepSimulation( deltaTime, 10 );
// Update rope
const softBody = rope.userData.physicsBody;
const ropePositions = rope.geometry.attributes.position.array;
const numVerts = ropePositions.length / 3;
const nodes = softBody.get_m_nodes();
let indexFloat = 0;
for ( let i = 0; i < numVerts; i ++ ) {
const node = nodes.at( i );
const nodePos = node.get_m_x();
ropePositions[ indexFloat ++ ] = nodePos.x();
ropePositions[ indexFloat ++ ] = nodePos.y();
ropePositions[ indexFloat ++ ] = nodePos.z();
}
rope.geometry.attributes.position.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>