+/**
+ * Transform a direction by a matrix.
+ */
+#define TRANSFORM_DIRECTION( TO, DIR, MAT ) \
+do { \
+ TO[0] = DIR[0] * MAT[0] + DIR[1] * MAT[4] + DIR[2] * MAT[8]; \
+ TO[1] = DIR[0] * MAT[1] + DIR[1] * MAT[5] + DIR[2] * MAT[9]; \
+ TO[2] = DIR[0] * MAT[2] + DIR[1] * MAT[6] + DIR[2] * MAT[10];\
+} while (0)
+
+
+extern void
+_mesa_transform_vector(GLfloat u[4], const GLfloat v[4], const GLfloat m[16]);
+
+