/*!
Create a normalized direction vector for an arbitraty set of rotation angles.
\param[in,out] dst The resulting direction vector will be stored in this variable.
\param[in] up_axis The up axis.
\param[in] rotx The X angle in degree.
\param[in] roty The Y angle in degree.
\param[in] rotz The Z angle in degree.
*/
void create_direction_vector( vec3 *dst, vec3 *up_axis, float rotx, float roty, float rotz )
{
vec4 rotation;
mat4 m;
mat4_identity( &m );
rotation.z = 1.0f;
rotation.x =
rotation.y = 0.0f;
rotation.w = rotz;
mat4_rotate( &m, &m, &rotation );
rotation.y = 1.0f;
rotation.x =
rotation.z = 0.0f;
rotation.w = roty;
mat4_rotate( &m, &m, &rotation );
rotation.x = 1.0f;
rotation.y =
rotation.z = 0.0f;
rotation.w = rotx;
mat4_rotate( &m, &m, &rotation );
vec3_invert( up_axis, up_axis );
vec3_multiply_mat4( dst, up_axis, &m );
}
void LAMP_get_direction_in_eye_space( LAMP *lamp, mat4 *m, vec3 *direction )
{
vec3_multiply_mat4( direction,
&lamp->direction,
m );
vec3_invert( direction, direction );
}