问题描述
嗨,我正在用 ThreeJS 开发一个基本的突破/打砖块游戏。现在我只有一个桨和一个在屏幕上弹跳的球。我试图让碰撞起作用,以便当球击中球拍时它会弹开。我一直在尝试使用边界框来实现这一点,但是我遇到了一个问题,即 .intersect/.intersectsBox 没有正确注册交叉点,我不知道为什么。以下是我到目前为止的代码 -
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(75,window.innerWidth / window.innerHeight,0.1,1000);
const renderer = new THREE.Webglrenderer();
renderer.setSize(window.innerWidth,window.innerHeight);
document.body.appendChild(renderer.domElement);
const geometry = new THREE.BoxGeometry(5,1,1);
const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 });
const cube = new THREE.Mesh(geometry,material);
var cubeBoxHelper = new THREE.BoxHelper(cube,0xff0000);
var boundingBoxPaddle = new THREE.Box3().setFromObject(cubeBoxHelper);
cubeBoxHelper.update();
const geometrySphere = new THREE.SphereGeometry(1,32,32);
const materialSphere = new THREE.MeshBasicMaterial({ color: 0xffff00 });
const sphere = new THREE.Mesh(geometrySphere,materialSphere);
var sphereBoxHelper = new THREE.BoxHelper(sphere,0xff0000);
var boundingBoxBall = new THREE.Box3().setFromObject(sphereBoxHelper);
sphereBoxHelper.update();
scene.add(cube,cubeBoxHelper,sphere,sphereBoxHelper);
sphere.position.y = 5;
camera.position.z = 15;
camera.position.y = 10;
var xSpeed = 0.0005;
var dx = 0.1;
var dy = 0.1;
function bounce()
{
if (sphere.position.x < -19 || sphere.position.x > 18.5)
{
dx = -dx;
}
if (sphere.position.y < -5 || sphere.position.y > 19)
{
dy = -dy;
}
sphere.position.x += dx;
sphere.position.y += dy;
sphereBoxHelper.update();
}
function intersect()
{
if (boundingBoxBall.intersect(boundingBoxPaddle) == true)
{
console.log("intersection");
}
}
const animate = function ()
{
requestAnimationFrame(animate);
document.addEventListener("keydown",onDocumentKeyDown,false);
function onDocumentKeyDown(event)
{
var keyCode = event.which;
if (keyCode == 65 && cube.position.x >= -18.5)
{
cube.position.x -= xSpeed;
}
else if (keyCode == 68 && cube.position.x <= 18)
{
cube.position.x += xSpeed;
}
cubeBoxHelper.update();
};
bounce();
intersect();
sphereBoxHelper.update();
renderer.render(scene,camera);
};
animate();
现在我已经设置了它,所以 intersect 函数只是登录到控制台,这样我就可以知道发生了什么。任何帮助都会很棒,因为我不确定我做错了什么。
解决方法
.intersect ( box : Box3 ) : 这个 box - 要与之相交的框。
计算 this 和 box 的交集,将这个 box 的上界设置为两个 box 上界中较小的一个,并将这个 box 的下界设置为两个 box 下界中较大的一个。如果没有重叠,则将此框留空。
这个函数实际上做的是用来自 boundingBoxBall
的信息更新 boundingBoxPaddle
,甚至可能将 boundingBoxBall
设置为一个空框!
我认为您真正追求的功能是:
.intersectsBox ( box : Box3 ) : 布尔值 box - 检查交叉点的框。
确定此框是否与框相交。
intersectsBox
函数返回一个简单的 true
/false
,因此您可以判断两个框是否发生碰撞。
另请注意,您的边界框是相对于相关几何体的。如果您转换 Mesh
,那么您还需要转换边界框。 Box3 docs
上的示例代码实际上突出显示了这一点:
const box = new THREE.Box3();
// ...
// in the animation loop,compute the current bounding box with the world matrix
box.copy( mesh.geometry.boundingBox ).applyMatrix4( mesh.matrixWorld );
完整示例:
let W = window.innerWidth;
let H = window.innerHeight;
const renderer = new THREE.WebGLRenderer({
antialias: true,alpha: true
});
document.body.appendChild(renderer.domElement);
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(28,1,1000);
camera.position.set(0,50);
camera.lookAt(scene.position);
scene.add(camera);
const light = new THREE.DirectionalLight(0xffffff,1);
light.position.set(0,-1);
camera.add(light);
let geo = new THREE.BoxBufferGeometry(5,5,5);
geo.computeBoundingBox();
let mat = new THREE.MeshPhongMaterial({
color: "red"
});
const left = new THREE.Mesh(geo,mat);
left.position.set(-15,0)
scene.add(left);
const right = new THREE.Mesh(geo,mat);
right.position.set(15,0)
scene.add(right);
geo = new THREE.SphereBufferGeometry(1,16,16);
geo.computeBoundingBox();
mat = new THREE.MeshPhongMaterial({
color: "yellow"
});
const ball = new THREE.Mesh(geo,mat);
scene.add(ball);
function render() {
renderer.render(scene,camera);
}
function resize() {
W = window.innerWidth;
H = window.innerHeight;
renderer.setSize(W,H);
camera.aspect = W / H;
camera.updateProjectionMatrix();
render();
}
let rate = 0.1;
let goingRight = true;
let ballBox = new THREE.Box3();
let wallBox = new THREE.Box3();
function animate() {
render();
ball.position.x += ((goingRight) ? 1 : -1) * rate;
ball.updateMatrix();
ball.updateMatrixWorld(true);
ballBox.copy(ball.geometry.boundingBox);
ballBox.applyMatrix4(ball.matrixWorld);
if (goingRight) {
wallBox.copy(right.geometry.boundingBox);
wallBox.applyMatrix4(right.matrixWorld);
if (ballBox.intersectsBox(wallBox)) {
goingRight = false;
}
} else {
wallBox.copy(left.geometry.boundingBox);
wallBox.applyMatrix4(left.matrixWorld);
if (ballBox.intersectsBox(wallBox)) {
goingRight = true;
}
}
requestAnimationFrame(animate);
}
window.addEventListener("resize",resize);
resize();
requestAnimationFrame(animate);
html,body {
width: 100%;
height: 100%;
padding: 0;
margin: 0;
overflow: hidden;
background: skyblue;
}
<script src="https://threejs.org/build/three.min.js"></script>