pick mat3 from mat4

include/cglm-mat.h

@@ -63,6 +63,32 @@ glm_mat4_dup(mat4 mat, mat4 dest) {
 #endif
 }
 
+/*!
+ * @brief copy top-left of mat4 to mat3
+ *
+ * @param[in]  mat  source
+ * @param[out] dest destination
+ */
+CGLM_INLINE
+void
+glm_mat4_pick3(mat4 mat, mat3 dest) {
+#if defined( __SSE__ ) || defined( __SSE2__ )
+  glm_mat4_pick3_sse2(mat, dest);
+#else
+  dest[0][0] = mat[0][0];
+  dest[0][1] = mat[0][1];
+  dest[0][2] = mat[0][2];
+
+  dest[1][0] = mat[1][0];
+  dest[1][1] = mat[1][1];
+  dest[1][2] = mat[1][2];
+
+  dest[2][0] = mat[2][0];
+  dest[2][1] = mat[2][1];
+  dest[2][2] = mat[2][2];
+#endif
+}
+
 /*!
  * @brief multiply m1 and m2 to dest
  *