javascript - 3D Engine 在旋转时拉伸(stretch)物体

Question

我制作了一个小型 3d 引擎。

但我在旋转功能方面遇到了一些问题。 它们使物体不时拉伸(stretch)。 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;
    }
}

Answer 1

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;

您正在计算 y 并使用这个新的 y 来计算 z。您可能应该使用旧的 y(旋转之前):

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;