threejs/examples/js/physics/OimoPhysics.js

( function () {

	async function OimoPhysics() {

		const frameRate = 60;
		const world = new OIMO.World( 2, new OIMO.Vec3( 0, - 9.8, 0 ) );

		//

		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 new OIMO.OBoxGeometry( new OIMO.Vec3( sx, sy, sz ) );

			} else if ( geometry.type === 'SphereGeometry' || geometry.type === 'IcosahedronGeometry' ) {

				const radius = parameters.radius !== undefined ? parameters.radius : 1;
				return new OIMO.OSphereGeometry( radius );

			}

			return null;

		}

		const meshes = [];
		const meshMap = new WeakMap();
		function addMesh( mesh, mass = 0 ) {

			const shape = getShape( mesh.geometry );
			if ( shape !== null ) {

				if ( mesh.isInstancedMesh ) {

					handleInstancedMesh( mesh, mass, shape );

				} else if ( mesh.isMesh ) {

					handleMesh( mesh, mass, shape );

				}

			}

		}

		function handleMesh( mesh, mass, shape ) {

			const shapeConfig = new OIMO.ShapeConfig();
			shapeConfig.geometry = shape;
			const bodyConfig = new OIMO.RigidBodyConfig();
			bodyConfig.type = mass === 0 ? OIMO.RigidBodyType.STATIC : OIMO.RigidBodyType.DYNAMIC;
			bodyConfig.position = new OIMO.Vec3( mesh.position.x, mesh.position.y, mesh.position.z );
			const body = new OIMO.RigidBody( bodyConfig );
			body.addShape( new OIMO.Shape( shapeConfig ) );
			world.addRigidBody( body );
			if ( mass > 0 ) {

				meshes.push( mesh );
				meshMap.set( mesh, body );

			}

		}

		function handleInstancedMesh( mesh, mass, shape ) {

			const array = mesh.instanceMatrix.array;
			const bodies = [];
			for ( let i = 0; i < mesh.count; i ++ ) {

				const index = i * 16;
				const shapeConfig = new OIMO.ShapeConfig();
				shapeConfig.geometry = shape;
				const bodyConfig = new OIMO.RigidBodyConfig();
				bodyConfig.type = mass === 0 ? OIMO.RigidBodyType.STATIC : OIMO.RigidBodyType.DYNAMIC;
				bodyConfig.position = new OIMO.Vec3( array[ index + 12 ], array[ index + 13 ], array[ index + 14 ] );
				const body = new OIMO.RigidBody( bodyConfig );
				body.addShape( new OIMO.Shape( shapeConfig ) );
				world.addRigidBody( body );
				bodies.push( body );

			}

			if ( mass > 0 ) {

				meshes.push( mesh );
				meshMap.set( mesh, bodies );

			}

		}

		//

		function setMeshPosition( mesh, position, index = 0 ) {

			if ( mesh.isInstancedMesh ) {

				const bodies = meshMap.get( mesh );
				const body = bodies[ index ];
				body.setPosition( new OIMO.Vec3( position.x, position.y, position.z ) );

			} else if ( mesh.isMesh ) {

				const body = meshMap.get( mesh );
				body.setPosition( new OIMO.Vec3( position.x, position.y, position.z ) );

			}

		}

		//

		let lastTime = 0;
		function step() {

			const time = performance.now();
			if ( lastTime > 0 ) {

				// console.time( 'world.step' );
				world.step( 1 / frameRate );
				// console.timeEnd( 'world.step' );

			}

			lastTime = time;

			//

			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 ];
						compose( body.getPosition(), body.getOrientation(), array, j * 16 );

					}

					mesh.instanceMatrix.needsUpdate = true;

				} else if ( mesh.isMesh ) {

					const body = meshMap.get( mesh );
					mesh.position.copy( body.getPosition() );
					mesh.quaternion.copy( body.getOrientation() );

				}

			}

		}

		// animate

		setInterval( step, 1000 / frameRate );
		return {
			addMesh: addMesh,
			setMeshPosition: setMeshPosition
			// addCompoundMesh
		};

	}

	function compose( position, quaternion, array, index ) {

		const x = quaternion.x,
			y = quaternion.y,
			z = quaternion.z,
			w = quaternion.w;
		const x2 = x + x,
			y2 = y + y,
			z2 = z + z;
		const xx = x * x2,
			xy = x * y2,
			xz = x * z2;
		const yy = y * y2,
			yz = y * z2,
			zz = z * z2;
		const wx = w * x2,
			wy = w * y2,
			wz = w * z2;
		array[ index + 0 ] = 1 - ( yy + zz );
		array[ index + 1 ] = xy + wz;
		array[ index + 2 ] = xz - wy;
		array[ index + 3 ] = 0;
		array[ index + 4 ] = xy - wz;
		array[ index + 5 ] = 1 - ( xx + zz );
		array[ index + 6 ] = yz + wx;
		array[ index + 7 ] = 0;
		array[ index + 8 ] = xz + wy;
		array[ index + 9 ] = yz - wx;
		array[ index + 10 ] = 1 - ( xx + yy );
		array[ index + 11 ] = 0;
		array[ index + 12 ] = position.x;
		array[ index + 13 ] = position.y;
		array[ index + 14 ] = position.z;
		array[ index + 15 ] = 1;

	}

	THREE.OimoPhysics = OimoPhysics;

} )();