关于摄像机矩阵

samanthena

184 //=========================================
185    /**
186    @brief 计算摄像机矩阵,这个可以去看有关的数学知识
187      摄像机变换
188      就是根据3个向量来进行摄像机变换
189
190      思路：点世界变幻的逆运算就是摄像机变换
191    @param
192    @return
193    */
194 //=========================================
195
196 void zybCamera::getViewMatrix(D3DXMATRIX* V)
197 {
198    // Keep camera's axes orthogonal to eachother
199    D3DXVec3Normalize(&_look, &_look);
200
201    D3DXVec3Cross(&_up, &_look, &_right);
202    D3DXVec3Normalize(&_up, &_up);
203
204    D3DXVec3Cross(&_right, &_up, &_look);
205    D3DXVec3Normalize(&_right, &_right);
206
207    // Build the view matrix:
208    float x = -D3DXVec3Dot(&_right, &_pos);
209    float y = -D3DXVec3Dot(&_up, &_pos);
210    float z = -D3DXVec3Dot(&_look, &_pos);
211
212    (*V)(0,0) = _right.x; (*V)(0, 1) = _up.x; (*V)(0, 2) = _look.x; (*V)(0, 3) = 0.0f;
213    (*V)(1,0) = _right.y; (*V)(1, 1) = _up.y; (*V)(1, 2) = _look.y; (*V)(1, 3) = 0.0f;
214    (*V)(2,0) = _right.z; (*V)(2, 1) = _up.z; (*V)(2, 2) = _look.z; (*V)(2, 3) = 0.0f;
215    (*V)(3,0) = x;        (*V)(3, 1) = y;     (*V)(3, 2) = z;       (*V)(3, 3) = 1.0f;
216
217 }

_up,_look,_right 既然已经是摄像机的上, 前, 右向量了,为什么(198-120行)还要再算一次, 直接赋给矩阵V有什么不一样吗?

aq_1000

浮点数偏差

space3344

为了保证彼此垂直