GPencil: Redesign soft eraser logic

The old logic was working if the eraser was moved towards the end of the stroke, but got ugly results when the eraser was done towards the start of the stroke.

1 files changed, 13 insertions, 37 deletions

diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
index 2bf1c8cda75..cb58542dc38 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -1366,8 +1366,7 @@ static void gp_free_stroke(bGPdata *gpd, bGPDframe *gpf, bGPDstroke *gps)
 static void gp_stroke_soft_refine(bGPDstroke *gps)
 {
 	bGPDspoint *pt = NULL;
-	bGPDspoint *pt_before = NULL;
-	bGPDspoint *pt_after = NULL;
+	bGPDspoint *pt2 = NULL;
 	int i;
 
 	/* check if enough points*/
@@ -1375,50 +1374,27 @@ static void gp_stroke_soft_refine(bGPDstroke *gps)
 		return;
 	}
 
-	/* loop all points from second to last minus one
-	 * to untag any point that is not surrounded by tagged points
-	 */
+	/* loop all points to untag any point that next is not tagged */
 	pt = gps->points;
 	for (i = 1; i < gps->totpoints - 1; i++, pt++) {
 		if (pt->flag & GP_SPOINT_TAG) {
-			pt_before = &gps->points[i - 1];
-			pt_after = &gps->points[i + 1];
-
-			/* if any of the side points are not tagged, mark to keep */
-			if (((pt_before->flag & GP_SPOINT_TAG) == 0) ||
-				((pt_after->flag & GP_SPOINT_TAG) == 0))
+			pt2 = &gps->points[i + 1];
+			if (((pt2->flag & GP_SPOINT_TAG) == 0))
 			{
-				pt->flag |= GP_SPOINT_TEMP_TAG;
-			}
-			else {
-				/* reduce opacity of extreme points */
-				if ((pt_before->flag & GP_SPOINT_TAG) == 0) {
-					pt_before->strength *= 0.5f;
-				}
-				if ((pt_after->flag & GP_SPOINT_TAG) == 0) {
-					pt_after->strength *= 0.5f;
-				}
+				pt->flag &= ~GP_SPOINT_TAG;
 			}
 		}
 	}
 
-	/* last point special case to get smoother transition */
+	/* loop reverse all points to untag any point that previous is not tagged */
 	pt = &gps->points[gps->totpoints - 1];
-	pt_before = &gps->points[gps->totpoints - 2];
-	if (pt->flag & GP_SPOINT_TAG) {
-		pt->flag |= GP_SPOINT_TEMP_TAG;
-		pt->strength = 0.0f;
-
-		pt->flag |= GP_SPOINT_TEMP_TAG;
-		pt_before->strength *= 0.5f;
-	}
-
-	/* now untag temp tagged */
-	pt = gps->points;
-	for (i = 0; i < gps->totpoints; i++, pt++) {
-		if (pt->flag & GP_SPOINT_TEMP_TAG) {
-			pt->flag &= ~GP_SPOINT_TAG;
-			pt->flag &= ~GP_SPOINT_TEMP_TAG;
+	for (i = gps->totpoints - 1; i > 0; i--, pt--) {
+		if (pt->flag & GP_SPOINT_TAG) {
+			pt2 = &gps->points[i - 1];
+			if (((pt2->flag & GP_SPOINT_TAG) == 0))
+			{
+				pt->flag &= ~GP_SPOINT_TAG;
+			}
 		}
 	}
 }