哪位高人指点一下落不明D3DMatrixScaling函数

martinwei

有这样一段代码，很简单：
D3DXMATRIX matScale;
D3DXMatrixScaling(&matScale,1.0f,1.0f,5.0f);

程序的结果是返回matScale矩阵，
小弟的疑惑就是这个matScale矩阵是一个单位矩阵经过了缩放操作之后得到的还是matScale矩阵本身经过缩放操作得到的？
谢谢！ [em14]

resplendence

下落不明- -

earlyfly

D3DXMatrixScaling
Builds a matrix that scales along the x-axis, the y-axis, and the z-axis.


D3DXMATRIX * D3DXMatrixScaling(
  D3DXMATRIX * pOut,
  FLOAT sx,
  FLOAT sy,
  FLOAT sz
);
Parameters
pOut
[in, out] Pointer to the D3DXMATRIX structure that is the result of the operation.
sx
[in] Scaling factor that is applied along the x-axis.
sy
[in] Scaling factor that is applied along the y-axis.
sz
[in] Scaling factor that is applied along the z-axis.
Return Values
Pointer to the scaling transformation D3DXMATRIX.

Remarks
The return value for this function is the same value returned in the pOut parameter. In this way, the D3DXMatrixScaling function can be used as a parameter for another function.

Requirements
Header: Declared in D3dx9math.h.


从msdn中可以看出，可能是矩阵本身经过缩放操作得到的……

martinwei

earlyfly: Re:哪位高人指点一下落不明D3DMatrixScaling函数

D3DXMatrixScaling
Builds a matrix that scales along the x-axis, the y-axis, and the z-axis.


D3...

呵呵,可是我书上有一个程序又像是一个单位矩阵经过一系列的变化得到的,具体代码如下:
一个物体在Z轴方向上放大5倍,然后又绕Y轴旋转60度,最后沿X轴平移30个单位,其实现代码如下:
D3DXMATRIX matWorld;
DEDXMATRIX matTranlate,matRotation,matScale;
DEDXMatrixScaling(&matScale,1.0f,1.0f,5.0f);  //在Z轴方向上放大5倍
FLOAT fAngle=60*(2.0f*D3DX_PI)/360.0f;
D3DXMatrixRotationY(&matRotation,fAngle);    //绕Y轴旋转60度
D3DXMatrixMultiply(&matWorld,&matScale,&matRotation);  //先放大,后旋转的复合
D3DXMatrixTranslation(&matTranlate,30.0f,0.0f,0.0f);  //沿X轴平移30个单位
D3DXMatrixMultiply(&matWorld,&matWold,&matTanlate);//最后结果
g_pd3dDevice->SetTransform(D3DTS_WORLD,&matWorld);
照这个例子看的话,那矩阵又好像是单位矩阵经过变换而来的呀

earlyfly

我也不明白，本人并没有这方面编程经验。期待高手的分析……