fix for own regression [#34096] ocean sim vertex color bug

Caused by my assumption that alpha wasn't used for vertex colors.

Infact it is used by blender-internal rendering, but typically only for blending strand particles.
Updated comments to note this.

1 files changed, 8 insertions, 3 deletions

diff --git a/source/blender/makesdna/DNA_meshdata_types.h b/source/blender/makesdna/DNA_meshdata_types.h
index ffa5e420fca..a189219b211 100644
--- a/source/blender/makesdna/DNA_meshdata_types.h
+++ b/source/blender/makesdna/DNA_meshdata_types.h
@@ -118,9 +118,14 @@ typedef struct MLoopUV {
 #define MLOOPUV_VERTSEL	2
 #define MLOOPUV_PINNED	4
 
-/* at the moment alpha is abused for vertex painting
- * and not used for transparency,
- * note that red and blue are _not_ swapped, as they are with #MCol */
+/**
+ * at the moment alpha is abused for vertex painting,
+ * otherwise it should _always_ be initialized to 255
+ * Mostly its not used for transparency...
+ * (except for blender-internal rendering, see [#34096]).
+ *
+ * \note red and blue are _not_ swapped, as they are with #MCol
+ */
 typedef struct MLoopCol {
 	char r, g, b, a;
 } MLoopCol;