2 files changed, 6 insertions, 4 deletions
diff --git a/source/blender/makesdna/DNA_mesh_types.h b/source/blender/makesdna/DNA_mesh_types.h
index 97355548b09..9912ec8ec3b 100644
--- a/source/blender/makesdna/DNA_mesh_types.h
+++ b/source/blender/makesdna/DNA_mesh_types.h
@@ -161,7 +161,8 @@ typedef struct Mesh {
 
   /**
    * An array of materials, with length #totcol. These can be overridden by material slots
-   * on #Object. Indices in #MPoly.mat_nr control which material is used for every face.
+   * on #Object. Indices in the "material_index" attribute control which material is used for every
+   * face.
    */
   struct Material **mat;
 
diff --git a/source/blender/makesdna/DNA_meshdata_types.h b/source/blender/makesdna/DNA_meshdata_types.h
index c62907e26ed..e0333f3ef03 100644
--- a/source/blender/makesdna/DNA_meshdata_types.h
+++ b/source/blender/makesdna/DNA_meshdata_types.h
@@ -74,7 +74,8 @@ typedef struct MPoly {
   int loopstart;
   /** Keep signed since we need to subtract when getting the previous loop. */
   int totloop;
-  short mat_nr;
+  /** Deprecated material index. Now stored in the "material_index" attribute, but kept for IO. */
+  short mat_nr DNA_DEPRECATED;
   char flag, _pad;
 } MPoly;
 
@@ -156,8 +157,8 @@ enum {
  *
  * Usage examples:
  * \code{.c}
- * // access original material.
- * short mat_nr = mpoly[lt->poly].mat_nr;
+ * // access polygon attribute value.
+ * T value = polygon_attribute[lt->poly];
  *
  * // access vertex locations.
  * float *vtri_co[3] = {