Fix T53577: Rake sculpt/paint wrong on first step

3 files changed, 15 insertions, 4 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index dff7f65b39a..07c4598c856 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -155,7 +155,7 @@ float paint_grid_paint_mask(const struct GridPaintMask *gpm, unsigned level,
                             unsigned x, unsigned y);
 
 /* stroke related */
-void paint_calculate_rake_rotation(struct UnifiedPaintSettings *ups, struct Brush *brush, const float mouse_pos[2]);
+bool paint_calculate_rake_rotation(struct UnifiedPaintSettings *ups, struct Brush *brush, const float mouse_pos[2]);
 void paint_update_brush_rake_rotation(struct UnifiedPaintSettings *ups, struct Brush *brush, float rotation);
 
 void BKE_paint_stroke_get_average(struct Scene *scene, struct Object *ob, float stroke[3]);
diff --git a/source/blender/blenkernel/intern/paint.c b/source/blender/blenkernel/intern/paint.c
index c1ad31a1cab..32813ffce25 100644
--- a/source/blender/blenkernel/intern/paint.c
+++ b/source/blender/blenkernel/intern/paint.c
@@ -638,8 +638,9 @@ void paint_update_brush_rake_rotation(UnifiedPaintSettings *ups, Brush *brush, f
 		ups->brush_rotation_sec = 0.0f;
 }
 
-void paint_calculate_rake_rotation(UnifiedPaintSettings *ups, Brush *brush, const float mouse_pos[2])
+bool paint_calculate_rake_rotation(UnifiedPaintSettings *ups, Brush *brush, const float mouse_pos[2])
 {
+	bool ok = false;
 	if ((brush->mtex.brush_angle_mode & MTEX_ANGLE_RAKE) || (brush->mask_mtex.brush_angle_mode & MTEX_ANGLE_RAKE)) {
 		const float r = RAKE_THRESHHOLD;
 		float rotation;
@@ -655,16 +656,20 @@ void paint_calculate_rake_rotation(UnifiedPaintSettings *ups, Brush *brush, cons
 			ups->last_rake_angle = rotation;
 
 			paint_update_brush_rake_rotation(ups, brush, rotation);
+			ok = true;
 		}
 		/* make sure we reset here to the last rotation to avoid accumulating
 		 * values in case a random rotation is also added */
 		else {
 			paint_update_brush_rake_rotation(ups, brush, ups->last_rake_angle);
+			ok = false;
 		}
 	}
 	else {
 		ups->brush_rotation = ups->brush_rotation_sec = 0.0f;
+		ok = true;
 	}
+	return ok;
 }
 
 void BKE_sculptsession_free_deformMats(SculptSession *ss)
diff --git a/source/blender/editors/sculpt_paint/paint_stroke.c b/source/blender/editors/sculpt_paint/paint_stroke.c
index 2c8e88e3ccb..c3055144b20 100644
--- a/source/blender/editors/sculpt_paint/paint_stroke.c
+++ b/source/blender/editors/sculpt_paint/paint_stroke.c
@@ -224,6 +224,9 @@ static bool paint_brush_update(bContext *C,
 	UnifiedPaintSettings *ups = stroke->ups;
 	bool location_sampled = false;
 	bool location_success = false;
+	/* Use to perform all operations except applying the stroke,
+	 * needed for operations that require cursor motion (rake). */
+	bool is_dry_run = false;
 	bool do_random = false;
 	bool do_random_mask = false;
 	/* XXX: Use pressure value from first brush step for brushes which don't
@@ -362,7 +365,10 @@ static bool paint_brush_update(bContext *C,
 		}
 		/* curve strokes do their own rake calculation */
 		else if (!(brush->flag & BRUSH_CURVE)) {
-			paint_calculate_rake_rotation(ups, brush, mouse_init);
+			if (!paint_calculate_rake_rotation(ups, brush, mouse_init)) {
+				/* Not enough motion to define an angle. */
+				is_dry_run = true;
+			}
 		}
 	}
 
@@ -393,7 +399,7 @@ static bool paint_brush_update(bContext *C,
 		}
 	}
 
-	return location_success;
+	return location_success && (is_dry_run == false);
 }
 
 static bool paint_stroke_use_jitter(ePaintMode mode, Brush *brush, bool invert)