Stage3D 中的PerspectiveMatrix3D

PerspectiveMatrix3D继承自Matrix3D。表示投影矩阵的功能类。

公式：用4X4矩阵向z=d的平面投影

public function perspectiveFieldOfViewLH(fieldOfViewY:Number,
                                                 aspectRatio:Number,
                                                 zNear:Number,
                                                 zFar:Number):void {
            var yScale:Number = 1.0/Math.tan(fieldOfViewY/2.0);
            var xScale:Number = yScale / aspectRatio;
            this.copyRawDataFrom(Vector.<Number>([
                xScale, 0.0, 0.0, 0.0,
                0.0, yScale, 0.0, 0.0,
                0.0, 0.0, zFar/(zFar-zNear), 1.0,
                0.0, 0.0, (zNear*zFar)/(zNear-zFar), 0.0
            ]));
        }

使用perspectiveFieldOfViewLH时，设定的是左手坐标系，投影平面在z=1的地方。

public function perspectiveFieldOfViewRH(fieldOfViewY:Number,
                                                 aspectRatio:Number,
                                                 zNear:Number,
                                                 zFar:Number):void {
            var yScale:Number = 1.0/Math.tan(fieldOfViewY/2.0);
            var xScale:Number = yScale / aspectRatio;
            this.copyRawDataFrom(Vector.<Number>([
                xScale, 0.0, 0.0, 0.0,
                0.0, yScale, 0.0, 0.0,
                0.0, 0.0, zFar/(zNear-zFar), -1.0,
                0.0, 0.0, (zNear*zFar)/(zNear-zFar), 0.0
            ]));
        }

使用perspectiveFieldOfViewRH时，设定的是右手坐标系，投影平面在z=-1的地方。

在实际应用中，要特别注意坐标系的选择，否则会出现屏幕上看不到物体的情况。