【发布时间】：2020-04-04 02:36:49
【问题描述】：
我正在尝试弄清楚如何使用 Three.js 和 Cannon.js 创建具有物理特性的最小汽车。我已经为我的汽车和车轮创建了基于视觉和物理的元素，并且我的汽车响应向上箭头和左/右箭头命令以加速和转弯：
var container = document.querySelector('body'),
w = container.clientWidth,
h = container.clientHeight,
scene = new THREE.Scene(),
camera = new THREE.PerspectiveCamera(75, w/h, 0.001, 100),
renderConfig = {antialias: true, alpha: true},
renderer = new THREE.WebGLRenderer(renderConfig);
camera.position.set(0, 1, -10);
camera.lookAt(0,0,0);
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(w, h);
container.appendChild(renderer.domElement);
window.addEventListener('resize', function() {
w = container.clientWidth;
h = container.clientHeight;
camera.aspect = w/h;
camera.updateProjectionMatrix();
renderer.setSize(w, h);
})
var geometry = new THREE.PlaneGeometry(10, 10, 10);
var material = new THREE.MeshBasicMaterial({color: 0xff0000, side: THREE.DoubleSide});
var plane = new THREE.Mesh(geometry, material);
plane.rotation.x = Math.PI/2;
scene.add(plane);
var sunlight = new THREE.DirectionalLight(0xffffff, 1.0);
sunlight.position.set(-10, 10, 0);
scene.add(sunlight)
/**
* Physics
**/
var world = new CANNON.World();
world.broadphase = new CANNON.SAPBroadphase(world);
world.gravity.set(0, -10, 0);
world.defaultContactMaterial.friction = 0;
var groundMaterial = new CANNON.Material('groundMaterial');
var wheelMaterial = new CANNON.Material('wheelMaterial');
var wheelGroundContactMaterial = new CANNON.ContactMaterial(wheelMaterial, groundMaterial, {
friction: 0.3,
restitution: 0,
contactEquationStiffness: 1000,
});
world.addContactMaterial(wheelGroundContactMaterial);
// car physics body
var chassisShape = new CANNON.Box(new CANNON.Vec3(1, 0.3, 2));
var chassisBody = new CANNON.Body({mass: 150});
chassisBody.addShape(chassisShape);
chassisBody.position.set(0, 0.2, 0);
chassisBody.angularVelocity.set(0, 0, 0); // initial velocity
// car visual body
var geometry = new THREE.BoxGeometry(2, 0.6, 4); // double chasis shape
var material = new THREE.MeshBasicMaterial({color: 0xffff00, side: THREE.DoubleSide});
var box = new THREE.Mesh(geometry, material);
scene.add(box);
// parent vehicle object
vehicle = new CANNON.RaycastVehicle({
chassisBody: chassisBody,
indexRightAxis: 0, // x
indexUpAxis: 1, // y
indexForwardAxis: 2, // z
});
// wheel options
var options = {
radius: 0.3,
directionLocal: new CANNON.Vec3(0, -1, 0),
suspensionStiffness: 45,
suspensionRestLength: 0.4,
frictionSlip: 5,
dampingRelaxation: 2.3,
dampingCompression: 4.5,
maxSuspensionForce: 200000,
rollInfluence: 0.01,
axleLocal: new CANNON.Vec3(-1, 0, 0),
chassisConnectionPointLocal: new CANNON.Vec3(1, 1, 0),
maxSuspensionTravel: 0.25,
customSlidingRotationalSpeed: -30,
useCustomSlidingRotationalSpeed: true,
};
var axlewidth = 0.7;
options.chassisConnectionPointLocal.set(axlewidth, 0, -1);
vehicle.addWheel(options);
options.chassisConnectionPointLocal.set(-axlewidth, 0, -1);
vehicle.addWheel(options);
options.chassisConnectionPointLocal.set(axlewidth, 0, 1);
vehicle.addWheel(options);
options.chassisConnectionPointLocal.set(-axlewidth, 0, 1);
vehicle.addWheel(options);
vehicle.addToWorld(world);
// car wheels
var wheelBodies = [],
wheelVisuals = [];
vehicle.wheelInfos.forEach(function(wheel) {
var shape = new CANNON.Cylinder(wheel.radius, wheel.radius, wheel.radius / 2, 20);
var body = new CANNON.Body({mass: 1, material: wheelMaterial});
var q = new CANNON.Quaternion();
q.setFromAxisAngle(new CANNON.Vec3(1, 0, 0), Math.PI / 2);
body.addShape(shape, new CANNON.Vec3(), q);
wheelBodies.push(body);
// wheel visual body
var geometry = new THREE.CylinderGeometry( wheel.radius, wheel.radius, 0.4, 32 );
var material = new THREE.MeshPhongMaterial({
color: 0xd0901d,
emissive: 0xaa0000,
side: THREE.DoubleSide,
flatShading: true,
});
var cylinder = new THREE.Mesh(geometry, material);
wheelVisuals.push(cylinder);
scene.add(cylinder);
});
// update the wheels to match the physics
world.addEventListener('postStep', function() {
for (var i=0; i<vehicle.wheelInfos.length; i++) {
vehicle.updateWheelTransform(i);
var t = vehicle.wheelInfos[i].worldTransform;
// update wheel physics
wheelBodies[i].position.copy(t.position);
wheelBodies[i].quaternion.copy(t.quaternion);
// update wheel visuals
wheelVisuals[i].position.copy(t.position);
wheelVisuals[i].quaternion.copy(t.quaternion);
}
});
var q = plane.quaternion;
var planeBody = new CANNON.Body({
mass: 0, // mass = 0 makes the body static
material: groundMaterial,
shape: new CANNON.Plane(),
quaternion: new CANNON.Quaternion(-q._x, q._y, q._z, q._w)
});
world.add(planeBody)
/**
* Main
**/
function updatePhysics() {
world.step(1/60);
// update the chassis position
box.position.copy(chassisBody.position);
box.quaternion.copy(chassisBody.quaternion);
}
function render() {
requestAnimationFrame(render);
renderer.render(scene, camera);
updatePhysics();
}
function navigate(e) {
if (e.type != 'keydown' && e.type != 'keyup') return;
var keyup = e.type == 'keyup';
vehicle.setBrake(0, 0);
vehicle.setBrake(0, 1);
vehicle.setBrake(0, 2);
vehicle.setBrake(0, 3);
var engineForce = 800,
maxSteerVal = 0.3;
switch(e.keyCode) {
case 38: // forward
vehicle.applyEngineForce(keyup ? 0 : -engineForce, 2);
vehicle.applyEngineForce(keyup ? 0 : -engineForce, 3);
break;
case 40: // backward
vehicle.applyEngineForce(keyup ? 0 : engineForce, 2);
vehicle.applyEngineForce(keyup ? 0 : engineForce, 3);
break;
case 39: // right
vehicle.setSteeringValue(keyup ? 0 : -maxSteerVal, 2);
vehicle.setSteeringValue(keyup ? 0 : -maxSteerVal, 3);
break;
case 37: // left
vehicle.setSteeringValue(keyup ? 0 : maxSteerVal, 2);
vehicle.setSteeringValue(keyup ? 0 : maxSteerVal, 3);
break;
}
}
window.addEventListener('keydown', navigate)
window.addEventListener('keyup', navigate)
render();* {
margin: 0;
padding: 0;
overflow: hidden;
}
html,
body,
canvas {
width: 100%;
height: 100%;
background: #aaa;
}<script src='https://cdnjs.cloudflare.com/ajax/libs/three.js/110/three.min.js'></script>
<script src='https://cdnjs.cloudflare.com/ajax/libs/cannon.js/0.6.2/cannon.js'></script>我现在正试图弄清楚如何旋转车轮，使它们像正确的轮胎一样滚动。以前，在world.addEventListener('postStep') 回调中，我在设置轮子的四元数后手动运行wheelVisuals[i].rotation.z = Math.PI/2。这一直很好，直到我转动汽车，此时轮胎被甩出对齐......
如果有人能指点一下如何使用 Cannon.js 配置轮子，我将不胜感激！
【问题讨论】：
标签： javascript three.js cannon.js