/
RapierPhysics.js
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/
RapierPhysics.js
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import { Clock, Vector3, Quaternion, Matrix4 } from 'three';
const RAPIER_PATH = 'https://cdn.skypack.dev/@dimforge/rapier3d-compat@0.12.0';
const frameRate = 60;
const _scale = new Vector3( 1, 1, 1 );
const ZERO = new Vector3();
let RAPIER = null;
function getShape( geometry ) {
const parameters = geometry.parameters;
// TODO change type to is*
if ( geometry.type === 'BoxGeometry' ) {
const sx = parameters.width !== undefined ? parameters.width / 2 : 0.5;
const sy = parameters.height !== undefined ? parameters.height / 2 : 0.5;
const sz = parameters.depth !== undefined ? parameters.depth / 2 : 0.5;
return RAPIER.ColliderDesc.cuboid( sx, sy, sz );
} else if ( geometry.type === 'SphereGeometry' || geometry.type === 'IcosahedronGeometry' ) {
const radius = parameters.radius !== undefined ? parameters.radius : 1;
return RAPIER.ColliderDesc.ball( radius );
}
return null;
}
async function RapierPhysics() {
if ( RAPIER === null ) {
RAPIER = await import( RAPIER_PATH );
await RAPIER.init();
}
// Docs: https://rapier.rs/docs/api/javascript/JavaScript3D/
const gravity = new Vector3( 0.0, - 9.81, 0.0 );
const world = new RAPIER.World( gravity );
const meshes = [];
const meshMap = new WeakMap();
const _vector = new Vector3();
const _quaternion = new Quaternion();
const _matrix = new Matrix4();
function addScene( scene ) {
scene.traverse( function ( child ) {
if ( child.isMesh ) {
const physics = child.userData.physics;
if ( physics ) {
addMesh( child, physics.mass, physics.restitution );
}
}
} );
}
function addMesh( mesh, mass = 0, restitution = 0 ) {
const shape = getShape( mesh.geometry );
if ( shape === null ) return;
shape.setMass( mass );
shape.setRestitution( restitution );
const body = mesh.isInstancedMesh
? createInstancedBody( mesh, mass, shape )
: createBody( mesh.position, mesh.quaternion, mass, shape );
if ( mass > 0 ) {
meshes.push( mesh );
meshMap.set( mesh, body );
}
}
function createInstancedBody( mesh, mass, shape ) {
const array = mesh.instanceMatrix.array;
const bodies = [];
for ( let i = 0; i < mesh.count; i ++ ) {
const position = _vector.fromArray( array, i * 16 + 12 );
bodies.push( createBody( position, null, mass, shape ) );
}
return bodies;
}
function createBody( position, quaternion, mass, shape ) {
const desc = mass > 0 ? RAPIER.RigidBodyDesc.dynamic() : RAPIER.RigidBodyDesc.fixed();
desc.setTranslation( ...position );
if ( quaternion !== null ) desc.setRotation( quaternion );
const body = world.createRigidBody( desc );
world.createCollider( shape, body );
return body;
}
function setMeshPosition( mesh, position, index = 0 ) {
let body = meshMap.get( mesh );
if ( mesh.isInstancedMesh ) {
body = body[ index ];
}
body.setAngvel( ZERO );
body.setLinvel( ZERO );
body.setTranslation( position );
}
function setMeshVelocity( mesh, velocity, index = 0 ) {
let body = meshMap.get( mesh );
if ( mesh.isInstancedMesh ) {
body = body[ index ];
}
body.setLinvel( velocity );
}
//
const clock = new Clock();
function step() {
world.timestep = clock.getDelta();
world.step();
//
for ( let i = 0, l = meshes.length; i < l; i ++ ) {
const mesh = meshes[ i ];
if ( mesh.isInstancedMesh ) {
const array = mesh.instanceMatrix.array;
const bodies = meshMap.get( mesh );
for ( let j = 0; j < bodies.length; j ++ ) {
const body = bodies[ j ];
const position = body.translation();
_quaternion.copy( body.rotation() );
_matrix.compose( position, _quaternion, _scale ).toArray( array, j * 16 );
}
mesh.instanceMatrix.needsUpdate = true;
mesh.computeBoundingSphere();
} else {
const body = meshMap.get( mesh );
mesh.position.copy( body.translation() );
mesh.quaternion.copy( body.rotation() );
}
}
}
// animate
setInterval( step, 1000 / frameRate );
return {
addScene: addScene,
addMesh: addMesh,
setMeshPosition: setMeshPosition,
setMeshVelocity: setMeshVelocity
};
}
export { RapierPhysics };