请教camera类void Camera::getViewMatrix(D3DXMATRIX* V)的一个不懂的

kongbu

void Camera::getViewMatrix(D3DXMATRIX* V)
{
        // Keep camera's axes orthogonal to eachother
        D3DXVec3Normalize(&_look, &_look);

        D3DXVec3Cross(&_up, &_look, &_right);
        D3DXVec3Normalize(&_up, &_up);

        D3DXVec3Cross(&_right, &_up, &_look);
        D3DXVec3Normalize(&_right, &_right);

        // Build the view matrix:
        float x = -D3DXVec3Dot(&_right, &_pos);
        float y = -D3DXVec3Dot(&_up, &_pos);
        float z = -D3DXVec3Dot(&_look, &_pos);

        (*V)(0,0) = _right.x; (*V)(0, 1) = _up.x; (*V)(0, 2) = _look.x; (*V)(0, 3) = 0.0f;
        (*V)(1,0) = _right.y; (*V)(1, 1) = _up.y; (*V)(1, 2) = _look.y; (*V)(1, 3) = 0.0f;
        (*V)(2,0) = _right.z; (*V)(2, 1) = _up.z; (*V)(2, 2) = _look.z; (*V)(2, 3) = 0.0f;
        (*V)(3,0) = x;        (*V)(3, 1) = y;     (*V)(3, 2) = z;       (*V)(3, 3) = 1.0f;
}
为什么需要这样求到x,y,z
float x = -D3DXVec3Dot(&_right, &_pos);
float y = -D3DXVec3Dot(&_up, &_pos);
float z = -D3DXVec3Dot(&_look, &_pos);
而不是直接
float x = _pos.x;
float y = _pos.y;
float z = _pos.z;
看不懂, 有何意义？？？？？？
[em17] [em17] [em17] [em17] [em17] [em4] [em4] [em4] [em7] [em7] [em7]

quanyy

因为pos是旋转过后的，求他的逆不能直接取负

kongbu

恩，谢谢楼上的兄弟，　明白了