GPencil: Improve drawing feeling in big files

When drawing in big files, the first points of the stroke were not smooth because the system was doing a copy of the depsgraph datablock.

Now, the depsgraph is not updated at the beginning and the feeling is far better, especially for big files.

To avoid the copy, the original datablock is used while drawing, because it's faster the lookup of the original data, than a full datablock copy.

Also some cleanup of the code.

1 files changed, 13 insertions, 2 deletions

diff --git a/source/blender/draw/engines/gpencil/gpencil_engine.c b/source/blender/draw/engines/gpencil/gpencil_engine.c
index 1cc493dd8f5..3a74e44836d 100644
--- a/source/blender/draw/engines/gpencil/gpencil_engine.c
+++ b/source/blender/draw/engines/gpencil/gpencil_engine.c
@@ -617,9 +617,20 @@ void GPENCIL_cache_populate(void *vedata, Object *ob)
 		}
 
 		/* draw current painting strokes
-		 * (only if region is equal to originated paint region) */
+		 * (only if region is equal to originated paint region)
+		 *
+		 * Need to use original data because to use the copy of data, the paint
+		 * operator must update depsgraph and this makes that first events of the
+		 * mouse are missed if the datablock is very big due the time required to
+		 * copy the datablock. The search of the original data is faster than a
+		 * full datablock copy.
+		 * Using the original data doesn't require a copy and the feel when drawing
+		 * is far better.
+		 */
+
+		bGPdata *gpd_orig = (bGPdata *)DEG_get_original_id(&gpd->id);
 		if ((draw_ctx->obact == ob) &&
-		    ((gpd->runtime.ar == NULL) || (gpd->runtime.ar == draw_ctx->ar)))
+			((gpd_orig->runtime.ar == NULL) || (gpd_orig->runtime.ar == draw_ctx->ar)))
 		{
 			DRW_gpencil_populate_buffer_strokes(&e_data, vedata, ts, ob);
 		}