题
我制作了一个小型 3D 引擎。
但我对旋转功能有一些问题。它们时不时地使物体伸展。这是数学:
this.rotateX = function(angle) {
var cos = Math.cos(angle);
var sin = Math.sin(angle);
for(var i = 0; i < this.points.length; i++) {
this.points[i].y = sin * this.points[i].z + cos * this.points[i].y;
this.points[i].z = -sin * this.points[i].y + cos * this.points[i].z;
}
}
this.rotateY = function(angle) {
var cos = Math.cos(angle);
var sin = Math.sin(angle);
for(var i = 0; i < this.points.length; i++) {
this.points[i].x = cos * this.points[i].x - sin * this.points[i].z;
this.points[i].z = sin * this.points[i].x + cos * this.points[i].z;
}
}
this.rotateZ = function(angle) {
var cos = Math.cos(angle);
var sin = Math.sin(angle);
for(var i = 0; i < this.points.length; i++) {
this.points[i].x = cos * this.points[i].x + sin * this.points[i].y;
this.points[i].y = -sin * this.points[i].x + cos * this.points[i].y;
}
}
解决方案
this.points[i].y = sin * this.points[i].z + cos * this.points[i].y;
this.points[i].z = -sin * this.points[i].y + cos * this.points[i].z;
你正在计算 y
并使用这个新的 y
计算 z
. 。你可能应该使用旧的 y
(旋转前):
var y = sin * this.points[i].z + cos * this.points[i].y;
var z = -sin * this.points[i].y + cos * this.points[i].z;
this.points[i].y = y;
this.points[i].z = z;
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