diff options
Diffstat (limited to 'src/mesa/math/m_matrix.c')
| -rw-r--r-- | src/mesa/math/m_matrix.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/src/mesa/math/m_matrix.c b/src/mesa/math/m_matrix.c index 84b4cae4adb..58cae88b08b 100644 --- a/src/mesa/math/m_matrix.c +++ b/src/mesa/math/m_matrix.c @@ -1620,3 +1620,24 @@ _math_transposefd( GLfloat to[16], const GLdouble from[16] ) /*@}*/ + +/** + * Transform a 4-element row vector (1x4 matrix) by a 4x4 matrix. This + * function is used for transforming clipping plane equations and spotlight + * directions. + * Mathematically, u = v * m. + * Input: v - input vector + * m - transformation matrix + * Output: u - transformed vector + */ +void +_mesa_transform_vector( GLfloat u[4], const GLfloat v[4], const GLfloat m[16] ) +{ + const GLfloat v0 = v[0], v1 = v[1], v2 = v[2], v3 = v[3]; +#define M(row,col) m[row + col*4] + u[0] = v0 * M(0,0) + v1 * M(1,0) + v2 * M(2,0) + v3 * M(3,0); + u[1] = v0 * M(0,1) + v1 * M(1,1) + v2 * M(2,1) + v3 * M(3,1); + u[2] = v0 * M(0,2) + v1 * M(1,2) + v2 * M(2,2) + v3 * M(3,2); + u[3] = v0 * M(0,3) + v1 * M(1,3) + v2 * M(2,3) + v3 * M(3,3); +#undef M +} |