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。它们使物体不时伸展开来。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并使用新的y来计算z。您应该使用旧的y（轮换前）：

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;

3D引擎在旋转时拉伸物体

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