This is me trying to understand the code frmo this video
A Ball to grab hold of
// ------------------------------------------------------------------
class Ball {
constructor(pos, radius, vel)
{
// physics data
this.pos = pos;
this.radius = radius;
this.vel = vel;
this.grabbed = false;
// visual mesh
var geometry = new THREE.SphereGeometry( radius, 32, 32 );
var material = new THREE.MeshPhongMaterial({color: 0xff0000});
this.visMesh = new THREE.Mesh( geometry, material );
this.visMesh.position.copy(pos);
this.visMesh.userData = this; // for raycasting
this.visMesh.layers.enable(1);
gThreeScene.add(this.visMesh);
}
simulate()
{
if (this.grabbed)
return;
this.vel.addScaledVector(gPhysicsScene.gravity, gPhysicsScene.dt);
this.pos.addScaledVector(this.vel, gPhysicsScene.dt);
var size = gPhysicsScene.worldSize;
if (this.pos.x < -size.x) {
this.pos.x = -size.x; this.vel.x = -this.vel.x;
}
if (this.pos.x > size.x) {
this.pos.x = size.x; this.vel.x = -this.vel.x;
}
if (this.pos.z < -size.z) {
this.pos.z = -size.z; this.vel.z = -this.vel.z;
}
if (this.pos.z > size.z) {
this.pos.z = size.z; this.vel.z = -this.vel.z;
}
if (this.pos.y < this.radius) {
this.pos.y = this.radius; this.vel.y = -this.vel.y;
}
this.visMesh.position.copy(this.pos);
this.visMesh.geometry.computeBoundingSphere();
}
startGrab(pos)
{
this.grabbed = true;
this.pos.copy(pos);
this.visMesh.position.copy(pos);
}
moveGrabbed(pos, vel)
{
this.pos.copy(pos);
this.visMesh.position.copy(pos);
}
endGrab(pos, vel)
{
this.grabbed = false;
this.vel.copy(vel);
}
}
GRABBER class
// ------- grabber -----------------------------------------------------------
class Grabber {
constructor() {
this.raycaster = new THREE.Raycaster();
this.raycaster.layers.set(1);
this.raycaster.params.Line.threshold = 0.1;
this.physicsObject = null;
this.distance = 0.0;
this.prevPos = new THREE.Vector3();
this.vel = new THREE.Vector3();
this.time = 0.0;
}
increaseTime(dt) {
this.time += dt;
}
updateRaycaster(x, y) {
var rect = gRenderer.domElement.getBoundingClientRect();
this.mousePos = new THREE.Vector2();
this.mousePos.x = ((x - rect.left) / rect.width ) * 2 - 1;
this.mousePos.y = -((y - rect.top) / rect.height ) * 2 + 1;
this.raycaster.setFromCamera( this.mousePos, gCamera );
}
start(x, y) {
this.physicsObject = null;
this.updateRaycaster(x, y);
var intersects = this.raycaster.intersectObjects( gThreeScene.children );
if (intersects.length > 0) {
var obj = intersects[0].object.userData;
if (obj) {
this.physicsObject = obj;
this.distance = intersects[0].distance;
var pos = this.raycaster.ray.origin.clone();
pos.addScaledVector(this.raycaster.ray.direction, this.distance);
this.physicsObject.startGrab(pos);
this.prevPos.copy(pos);
this.vel.set(0.0, 0.0, 0.0);
this.time = 0.0;
if (gPhysicsScene.paused)
run();
}
}
}
move(x, y) {
if (this.physicsObject) {
this.updateRaycaster(x, y);
var pos = this.raycaster.ray.origin.clone();
pos.addScaledVector(this.raycaster.ray.direction, this.distance);
this.vel.copy(pos);
this.vel.sub(this.prevPos);
if (this.time > 0.0)
this.vel.divideScalar(this.time);
else
vel.set(0.0, 0.0, 0.0);
this.prevPos.copy(pos);
this.time = 0.0;
this.physicsObject.moveGrabbed(pos, this.vel);
}
}
end(x, y) {
if (this.physicsObject) {
this.physicsObject.endGrab(this.prevPos, this.vel);
this.physicsObject = null;
}
}
}
Event
function onPointer( evt )
{
event.preventDefault();
if (evt.type == "pointerdown") {
gGrabber.start(evt.clientX, evt.clientY);
gMouseDown = true;
if (gGrabber.physicsObject) {
gCameraControl.saveState();
gCameraControl.enabled = false;
}
}
else if (evt.type == "pointermove" && gMouseDown) {
gGrabber.move(evt.clientX, evt.clientY);
}
else if (evt.type == "pointerup") {
if (gGrabber.physicsObject) {
gGrabber.end();
gCameraControl.reset();
}
gMouseDown = false;
gCameraControl.enabled = true;
}
}
and to get it going
// ------------------------------------------------------------------
function simulate()
{
if (gPhysicsScene.paused)
return;
for (var i = 0; i < gPhysicsScene.objects.length; i++)
gPhysicsScene.objects[i].simulate();
gGrabber.increaseTime(gPhysicsScene.dt);
}
Set the Scene
var gThreeScene;
var gRenderer;
var gCamera;
var gCameraControl;
var gGrabber;
var gMouseDown = false;
var gPhysicsScene =
{
gravity : new THREE.Vector3(0.0, -10.0, 0.0),
dt : 1.0 / 60.0,
worldSize : { x: 1.5, z : 2.5 },
paused: true,
objects: [],
};
Three.js
// ------------------------------------------
function initThreeScene()
{
gThreeScene = new THREE.Scene();
// Lights
gThreeScene.add( new THREE.AmbientLight( 0x505050 ) );
gThreeScene.fog = new THREE.Fog( 0x000000, 0, 15 );
var spotLight = new THREE.SpotLight( 0xffffff );
spotLight.angle = Math.PI / 5;
spotLight.penumbra = 0.2;
spotLight.position.set( 2, 3, 3 );
spotLight.castShadow = true;
spotLight.shadow.camera.near = 3;
spotLight.shadow.camera.far = 10;
spotLight.shadow.mapSize.width = 1024;
spotLight.shadow.mapSize.height = 1024;
gThreeScene.add( spotLight );
var dirLight = new THREE.DirectionalLight( 0x55505a, 1 );
dirLight.position.set( 0, 3, 0 );
dirLight.castShadow = true;
dirLight.shadow.camera.near = 1;
dirLight.shadow.camera.far = 10;
dirLight.shadow.camera.right = 1;
dirLight.shadow.camera.left = - 1;
dirLight.shadow.camera.bottom = - 1;
dirLight.shadow.mapSize.width = 1024;
dirLight.shadow.mapSize.height = 1024;
gThreeScene.add( dirLight );
// Geometry
var ground = new THREE.Mesh(
new THREE.PlaneBufferGeometry( 20, 20, 1, 1 ),
new THREE.MeshPhongMaterial( { color: 0xa0adaf, shininess: 150 } )
);
ground.rotation.x = - Math.PI / 2; // rotates X/Y to X/Z
ground.receiveShadow = true;
gThreeScene.add( ground );
var helper = new THREE.GridHelper( 20, 20 );
helper.material.opacity = 1.0;
helper.material.transparent = true;
helper.position.set(0, 0.002, 0);
gThreeScene.add( helper );
// Renderer
gRenderer = new THREE.WebGLRenderer();
gRenderer.shadowMap.enabled = true;
gRenderer.setPixelRatio( window.devicePixelRatio );
gRenderer.setSize( 0.8 window.innerWidth, 0.8 window.innerHeight );
window.addEventListener( 'resize', onWindowResize, false );
container.appendChild( gRenderer.domElement );
// Camera
gCamera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.01, 100);
gCamera.position.set(0, 1, 4);
gCamera.updateMatrixWorld();
gThreeScene.add(gCamera);
gCameraControl = new THREE.OrbitControls(gCamera, gRenderer.domElement);
gCameraControl.zoomSpeed = 2.0;
// grabber
gGrabber = new Grabber();
container.addEventListener( 'pointerdown', onPointer, false );
container.addEventListener( 'pointermove', onPointer, false );
container.addEventListener( 'pointerup', onPointer, false );
}
BOOT
// make browser to call us repeatedly -----------------------------------
function update() {
simulate();
gRenderer.render(gThreeScene, gCamera);
requestAnimationFrame(update);
}
initThreeScene();
onWindowResize();
initPhysics();
update();
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