绕任意轴旋转模型
更新时间: 2024-04-28 08:37:12
公司要做桥梁转体动画，难点就在于要让桥梁的模型绕着任意旋转轴去旋转，这个旋转轴可能不是xyz之一的坐标轴，也不是模型的中心点。
这要使用旋转矩阵去实现，具体原理在这里 绕任意不穿过原点轴的四维旋转矩阵
效果如下：绿色的方块会绕着亮蓝色的轴线为中心旋转。
代码：
let container,scene,perpCamera,renderer,cube,line
let rotateMatrix = new THREE.Matrix4()
rotateMatrix.set(1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1)
let params = {
angle: 0,
start:{
x:1,
y:2,
z:1
},
end:{
x:2,
y:1,
z:1
}
}
let gui
init()
function init() {
container = document.getElementById('myTest')
scene = new THREE.Scene()
scene.background = new THREE.Color(0xffffff)
const width = container.clientWidth
const height = container.clientHeight
perpCamera = new THREE.PerspectiveCamera( 60, width/height, 1, 1000)
perpCamera.position.set(0,0,10)
scene.add(perpCamera)
const directionalLight = new THREE.DirectionalLight( 0xffffff, 1 );
directionalLight.position.set(1,1,1)
scene.add( directionalLight );
const directionalLight1 = new THREE.DirectionalLight( 0xffffff, 0.5 );
directionalLight1.position.set(-1,-1,-1)
scene.add( directionalLight1 );
renderer = new THREE.WebGLRenderer({antialias: true})
renderer.autoClear = false
renderer.setPixelRatio(window.devicePixelRatio)
renderer.setSize(width, height)
container.appendChild(renderer.domElement)
const controls = new OrbitControls(perpCamera, renderer.domElement)
controls.addEventListener('change', render)
var gui = new dat.GUI({},container)
gui.add(params,'angle', 0, 360)
.onChange(function() {
rotate()
render()
})
gui.add(params.start,'x',-10,10).name('start-x')
.onChange(function() {
changeAxis()
rotate()
render()
})
gui.add(params.start,'y',-10,10).name('start-y')
.onChange(function() {
changeAxis()
rotate()
render()
})
gui.add(params.start,'y',-10,10).name('start-y')
.onChange(function() {
changeAxis()
rotate()
render()
})
gui.add(params.end,'x',-10,10).name('end-x')
.onChange(function() {
changeAxis()
rotate()
render()
})
gui.add(params.end,'y',-10,10).name('end-y')
.onChange(function() {
changeAxis()
rotate()
render()
})
gui.add(params.end,'z',-10,10).name('end-z')
.onChange(function() {
changeAxis()
rotate()
render()
})
const axesHelper = new THREE.AxesHelper( 5 );
scene.add( axesHelper );
// 添加测试模型进去
addModel()
render()
}
function render() {
renderer.clear()
renderer.render(scene,perpCamera)
}
function addModel() {
const geometry = new THREE.BoxGeometry( 1, 1, 1 );
const material = new THREE.MeshLambertMaterial( {color: 0x00ff00} );
cube = new THREE.Mesh( geometry, material );
scene.add( cube );
// 添加旋转轴
const material1 = new THREE.LineBasicMaterial({
color: 0x00ffff
});
const points = [];
points.push( new THREE.Vector3( params.start.x, params.start.y, params.start.z ) );
points.push( new THREE.Vector3( params.end.x, params.end.y, params.end.z ) );
const geometry1 = new THREE.BufferGeometry().setFromPoints( points );
line = new THREE.Line( geometry1, material1 );
scene.add( line );
rotate()
}
function changeAxis() {
const geometry = line.geometry
geometry.attributes.position.setXYZ(0, params.start.x, params.start.y, params.start.z);
geometry.attributes.position.setXYZ(1, params.end.x, params.end.y, params.end.z);
geometry.attributes.position.needsUpdate = true;
}
function rotate() {
// 平移[-start[0], -start[1], -start[2]]
// 然后绕 [end[0]-start[0], end[1]-start[1], end[2]-start[2]]旋转angle角度
// 平移[start[0], start[1], start[2]]
// 注意threejs中的matrix4是右乘
const iMatrix = cube.matrix.clone().invert()
cube.applyMatrix4(iMatrix)
const px = params.start.x
const py = params.start.y
const pz = params.start.z
const ex = params.end.x
const ey = params.end.y
const ez = params.end.z
// 注意这里要归一化
const vecn = new THREE.Vector3(ex-px, ey-py, ez-pz).normalize()
const nx = vecn.x
const ny = vecn.y
const nz = vecn.z
// 平移
const matrix1 = new THREE.Matrix4()
matrix1.makeTranslation(-px, -py, -pz)
// 旋转
const matrix3 = new THREE.Matrix4()
matrix3.makeRotationAxis(vecn, params.angle * Math.PI / 180)
// 平移回来
const matrix2 = new THREE.Matrix4()
matrix2.makeTranslation(px, py, pz)
// 右乘，所以顺序是反的
const newMatrix = matrix2.clone().multiply(matrix3).multiply(matrix1)
rotateMatrix = newMatrix
cube.applyMatrix4(newMatrix)
}
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