matrix: trace of matrix

docs/source/mat3.rst

@@ -29,6 +29,7 @@ Functions:
 #. :c:func:`glm_mat3_scale`
 #. :c:func:`glm_mat3_det`
 #. :c:func:`glm_mat3_inv`
+#. :c:func:`glm_mat3_trace`
 #. :c:func:`glm_mat3_swap_col`
 #. :c:func:`glm_mat3_swap_row`
 
@@ -133,6 +134,16 @@ Functions documentation
       | *[in]*  **mat**  matrix
       | *[out]* **dest** destination (inverse matrix)
 
+.. c:function:: void glm_mat3_trace(mat3 m)
+
+    | sum of the elements on the main diagonal from upper left to the lower right
+
+    Parameters:
+      | *[in]*  **m**  matrix
+
+    Returns:
+        trace of matrix
+
 .. c:function:: void  glm_mat3_swap_col(mat3 mat, int col1, int col2)
 
     swap two matrix columns

docs/source/mat4.rst

@@ -33,6 +33,8 @@ Functions:
 #. :c:func:`glm_mat4_mulN`
 #. :c:func:`glm_mat4_mulv`
 #. :c:func:`glm_mat4_mulv3`
+#. :c:func:`glm_mat3_trace`
+#. :c:func:`glm_mat3_trace3`
 #. :c:func:`glm_mat4_quat`
 #. :c:func:`glm_mat4_transpose_to`
 #. :c:func:`glm_mat4_transpose`
@@ -156,6 +158,27 @@ Functions documentation
     | *[in]*  **v**     vec3 (right, column vector)
     | *[out]* **dest**  vec3 (result, column vector)
 
+.. c:function:: void  glm_mat4_trace(mat4 m)
+
+    | sum of the elements on the main diagonal from upper left to the lower right
+
+    Parameters:
+      | *[in]*  **m**  matrix
+
+    Returns:
+        trace of matrix
+
+.. c:function:: void  glm_mat4_trace3(mat4 m)
+
+    | trace of matrix (rotation part)
+    | sum of the elements on the main diagonal from upper left to the lower right
+
+    Parameters:
+      | *[in]*  **m**  matrix
+
+    Returns:
+        trace of matrix
+
 .. c:function:: void  glm_mat4_quat(mat4 m, versor dest)
 
     convert mat4's rotation part to quaternion

include/cglm/call/mat3.h

@@ -44,6 +44,10 @@ CGLM_EXPORT
 void
 glmc_mat3_mulv(mat3 m, vec3 v, vec3 dest);
 
+CGLM_EXPORT
+float
+glmc_mat3_trace(mat3 m);
+
 CGLM_EXPORT
 void
 glmc_mat3_quat(mat3 m, versor dest);

include/cglm/call/mat4.h

@@ -61,6 +61,14 @@ CGLM_EXPORT
 void
 glmc_mat4_mulv3(mat4 m, vec3 v, float last, vec3 dest);
 
+CGLM_EXPORT
+float
+glmc_mat4_trace(mat4 m);
+
+CGLM_EXPORT
+float
+glmc_mat4_trace3(mat4 m);
+
 CGLM_EXPORT
 void
 glmc_mat4_quat(mat4 m, versor dest);

include/cglm/mat3.h

@@ -21,6 +21,7 @@
    CGLM_INLINE void  glm_mat3_transpose_to(mat3 m, mat3 dest);
    CGLM_INLINE void  glm_mat3_transpose(mat3 m);
    CGLM_INLINE void  glm_mat3_mulv(mat3 m, vec3 v, vec3 dest);
+   CGLM_INLINE float glm_mat3_trace(mat3 m);
    CGLM_INLINE void  glm_mat3_scale(mat3 m, float s);
    CGLM_INLINE float glm_mat3_det(mat3 mat);
    CGLM_INLINE void  glm_mat3_inv(mat3 mat, mat3 dest);
@@ -207,6 +208,18 @@ glm_mat3_mulv(mat3 m, vec3 v, vec3 dest) {
   dest[2] = m[0][2] * v[0] + m[1][2] * v[1] + m[2][2] * v[2];
 }
 
+/*!
+ * @brief trace of matrix
+ *
+ * sum of the elements on the main diagonal from upper left to the lower right
+ *
+ * @param[in]  m matrix
+ */
+CGLM_INLINE
+float
+glm_mat3_trace(mat3 m) {
+  return m[0][0] + m[1][1] + m[2][2];
+}
 
 /*!
  * @brief convert mat3 to quaternion

include/cglm/mat4.h

@@ -29,6 +29,8 @@
    CGLM_INLINE void  glm_mat4_mulN(mat4 *matrices[], int len, mat4 dest);
    CGLM_INLINE void  glm_mat4_mulv(mat4 m, vec4 v, vec4 dest);
    CGLM_INLINE void  glm_mat4_mulv3(mat4 m, vec3 v, vec3 dest);
+   CGLM_INLINE float glm_mat4_trace(mat4 m);
+   CGLM_INLINE float glm_mat4_trace3(mat4 m);
    CGLM_INLINE void  glm_mat4_transpose_to(mat4 m, mat4 dest);
    CGLM_INLINE void  glm_mat4_transpose(mat4 m);
    CGLM_INLINE void  glm_mat4_scale_p(mat4 m, float s);
@@ -338,6 +340,32 @@ glm_mat4_mulv(mat4 m, vec4 v, vec4 dest) {
 #endif
 }
 
+/*!
+ * @brief trace of matrix
+ *
+ * sum of the elements on the main diagonal from upper left to the lower right
+ *
+ * @param[in]  m matrix
+ */
+CGLM_INLINE
+float
+glm_mat4_trace(mat4 m) {
+  return m[0][0] + m[1][1] + m[2][2] + m[3][3];
+}
+
+/*!
+ * @brief trace of matrix (rotation part)
+ *
+ * sum of the elements on the main diagonal from upper left to the lower right
+ *
+ * @param[in]  m matrix
+ */
+CGLM_INLINE
+float
+glm_mat4_trace3(mat4 m) {
+  return m[0][0] + m[1][1] + m[2][2];
+}
+
 /*!
  * @brief convert mat4's rotation part to quaternion
  *

src/mat3.c

@@ -50,6 +50,12 @@ glmc_mat3_mulv(mat3 m, vec3 v, vec3 dest) {
   glm_mat3_mulv(m, v, dest);
 }
 
+CGLM_EXPORT
+float
+glmc_mat3_trace(mat3 m) {
+  return glm_mat3_trace(m);
+}
+
 CGLM_EXPORT
 void
 glmc_mat3_quat(mat3 m, versor dest) {

src/mat4.c

@@ -74,6 +74,18 @@ glmc_mat4_mulv3(mat4 m, vec3 v, float last, vec3 dest) {
   glm_mat4_mulv3(m, v, last, dest);
 }
 
+CGLM_EXPORT
+float
+glmc_mat4_trace(mat4 m) {
+  return glm_mat4_trace(m);
+}
+
+CGLM_EXPORT
+float
+glmc_mat4_trace3(mat4 m) {
+  return glm_mat4_trace3(m);
+}
+
 CGLM_EXPORT
 void
 glmc_mat4_quat(mat4 m, versor dest) {