[英]How to rotate 3d point?
我目前正在用js开发3d渲染器。
我想渲染多维数据集-效果很好-但我想做的是每个多维数据集的旋转。
因此,我得到了一个立方体的某个顶点,我想围绕其自身旋转每个立方体的x / y / z(俯仰,滚动,偏航)。
这是3D旋转功能:
let rotate3d = (points = [0,0,0], pitch = 0, roll = 0, yaw = 0) => {
let cosa = Math.cos(yaw),
sina = Math.sin(yaw);
let cosb = Math.cos(pitch),
sinb = Math.sin(pitch);
let cosc = Math.cos(roll),
sinc = Math.sin(roll);
let Axx = cosa*cosb,
Axy = cosa*sinb*sinc - sina*cosc,
Axz = cosa*sinb*cosc + sina*sinc;
let Ayx = sina*cosb,
Ayy = sina*sinb*sinc + cosa*cosc,
Ayz = sina*sinb*cosc - cosa*sinc;
let Azx = -sinb,
Azy = cosb*sinc,
Azz = cosb*cosc;
let px = points[0];
let py = points[1];
let pz = points[2];
points[0] = Axx*px + Axy*py + Axz*pz;
points[1] = Ayx*px + Ayy*py + Ayz*pz;
points[2] = Azx*px + Azy*py + Azz*pz;
return points;
}
这是我的渲染器例程的摘录:
for (let vert of cube.vertex) { let x = vert[0] - camera.position[0], y = vert[1] - camera.position[1], z = vert[2] - camera.position[2]; if (cube.rotation) { cube.rotation += Math.PI * 0.02; let p = rotate(vert.slice(0), cube.r, 0, 0) x = p[0] - camera.position[0] y = p[1] - camera.position[1] z = p[2] - camera.position[2] } # ... draw polygons (cube) by converting 3d coordinates to 2d coordinates. }
因此 :如果以[0,-1,0]生成立方体,则程序将绕y轴(顺时针)旋转该立方体。 但是将生成物更改为[1,-1,0]可使多维数据集绕同一个点(原点)旋转,但空间为1。我想在生成物上旋转多维数据集!
编辑 :这是生成多维数据集例程:
spawn(p) {
this.position = p;
const vertex = [[-1,-1,-1], [1,-1,-1], [1,1,-1], [-1,1,-1], [-1,-1,1], [1,-1,1], [1,1,1], [-1,1,1]];
this.vertex = []
for (let vert of vertex) {
let position = []
for (let i=0; i<vert.length; i++) position.push(vert[i]/2 + this.position[i])
this.vertex.push(position)
}
}
所以我的问题是:如何编辑旋转功能以在要旋转立方体的地方添加原点?
指定旋转点的最简单方法是:
在(伪)代码中:
var translationVector = originPoint.minus(rotationPoint);
myObject.translate(translationVector);
myObject.rotate(eulerX, eulerY, eulerZ);
myObject.translate(-translationVector);
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