+/**
+ * \defgroup MatFlags MAT_FLAG_XXX-flags
+ *
+ * Bitmasks to indicate different kinds of 4x4 matrices in GLmatrix::flags
+ * It would be nice to make all these flags private to m_matrix.c
+ */
+/*@{*/
+#define MAT_FLAG_IDENTITY 0 /**< is an identity matrix flag.
+ * (Not actually used - the identity
+ * matrix is identified by the absense
+ * of all other flags.)
+ */
+#define MAT_FLAG_GENERAL 0x1 /**< is a general matrix flag */
+#define MAT_FLAG_ROTATION 0x2 /**< is a rotation matrix flag */
+#define MAT_FLAG_TRANSLATION 0x4 /**< is a translation matrix flag */
+#define MAT_FLAG_UNIFORM_SCALE 0x8 /**< is an uniform scaling matrix flag */
+#define MAT_FLAG_GENERAL_SCALE 0x10 /**< is a general scaling matrix flag */
+#define MAT_FLAG_GENERAL_3D 0x20 /**< general 3D matrix flag */
+#define MAT_FLAG_PERSPECTIVE 0x40 /**< is a perspective proj matrix flag */
+#define MAT_FLAG_SINGULAR 0x80 /**< is a singular matrix flag */
+#define MAT_DIRTY_TYPE 0x100 /**< matrix type is dirty */
+#define MAT_DIRTY_FLAGS 0x200 /**< matrix flags are dirty */
+#define MAT_DIRTY_INVERSE 0x400 /**< matrix inverse is dirty */
+
+/** angle preserving matrix flags mask */
+#define MAT_FLAGS_ANGLE_PRESERVING (MAT_FLAG_ROTATION | \
+ MAT_FLAG_TRANSLATION | \
+ MAT_FLAG_UNIFORM_SCALE)
+
+/** geometry related matrix flags mask */
+#define MAT_FLAGS_GEOMETRY (MAT_FLAG_GENERAL | \
+ MAT_FLAG_ROTATION | \
+ MAT_FLAG_TRANSLATION | \
+ MAT_FLAG_UNIFORM_SCALE | \
+ MAT_FLAG_GENERAL_SCALE | \
+ MAT_FLAG_GENERAL_3D | \
+ MAT_FLAG_PERSPECTIVE | \
+ MAT_FLAG_SINGULAR)
+
+/** length preserving matrix flags mask */
+#define MAT_FLAGS_LENGTH_PRESERVING (MAT_FLAG_ROTATION | \
+ MAT_FLAG_TRANSLATION)
+
+
+/** 3D (non-perspective) matrix flags mask */
+#define MAT_FLAGS_3D (MAT_FLAG_ROTATION | \
+ MAT_FLAG_TRANSLATION | \
+ MAT_FLAG_UNIFORM_SCALE | \
+ MAT_FLAG_GENERAL_SCALE | \
+ MAT_FLAG_GENERAL_3D)
+
+/** dirty matrix flags mask */
+#define MAT_DIRTY (MAT_DIRTY_TYPE | \
+ MAT_DIRTY_FLAGS | \
+ MAT_DIRTY_INVERSE)
+
+/*@}*/
+
+
+/**
+ * Test geometry related matrix flags.
+ *
+ * \param mat a pointer to a GLmatrix structure.
+ * \param a flags mask.
+ *
+ * \returns non-zero if all geometry related matrix flags are contained within
+ * the mask, or zero otherwise.
+ */
+#define TEST_MAT_FLAGS(mat, a) \
+ ((MAT_FLAGS_GEOMETRY & (~(a)) & ((mat)->flags) ) == 0)
+
+
+