Fix T44604 bad quality of rake with bezier curves.

We can calculate tangents analytically for bezier curves, so just make
them awesome. New code uses forward differencing calculation for
efficiency just like curve calculation.

Picture before/after:

http://www.pasteall.org/pic/87843

1 files changed, 28 insertions, 2 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_stroke.c b/source/blender/editors/sculpt_paint/paint_stroke.c
index 2ae544706df..d5c3e7e7fab 100644
--- a/source/blender/editors/sculpt_paint/paint_stroke.c
+++ b/source/blender/editors/sculpt_paint/paint_stroke.c
@@ -347,7 +347,8 @@ static bool paint_brush_update(bContext *C,
 		if (!stroke->brush_init) {
 			copy_v2_v2(ups->last_rake, mouse_init);
 		}
-		else {
+		/* curve strokes do their own rake calculation */
+		else if (!(brush->flag & BRUSH_CURVE)) {
 			paint_calculate_rake_rotation(ups, brush, mouse_init);
 		}
 	}
@@ -954,6 +955,7 @@ static bool paint_stroke_curve_end(bContext *C, wmOperator *op, PaintStroke *str
 	Brush *br = stroke->brush;
 
 	if (br->flag & BRUSH_CURVE) {
+		UnifiedPaintSettings *ups = &CTX_data_tool_settings(C)->unified_paint_settings;
 		const Scene *scene = CTX_data_scene(C);
 		const float spacing = paint_space_stroke_spacing(scene, stroke, 1.0f, 1.0f);
 		PaintCurve *pc = br->paint_curve;
@@ -974,29 +976,53 @@ static bool paint_stroke_curve_end(bContext *C, wmOperator *op, PaintStroke *str
 		for (i = 0; i < pc->tot_points - 1; i++, pcp++) {
 			int j;
 			float data[(PAINT_CURVE_NUM_SEGMENTS + 1) * 2];
+			float tangents[(PAINT_CURVE_NUM_SEGMENTS + 1) * 2];
 			PaintCurvePoint *pcp_next = pcp + 1;
+			bool do_rake = false;
 
-			for (j = 0; j < 2; j++)
+			for (j = 0; j < 2; j++) {
 				BKE_curve_forward_diff_bezier(
 				        pcp->bez.vec[1][j],
 				        pcp->bez.vec[2][j],
 				        pcp_next->bez.vec[0][j],
 				        pcp_next->bez.vec[1][j],
 				        data + j, PAINT_CURVE_NUM_SEGMENTS, sizeof(float[2]));
+			}
 
+			if ((br->mtex.brush_angle_mode & MTEX_ANGLE_RAKE) ||
+			    (br->mask_mtex.brush_angle_mode & MTEX_ANGLE_RAKE))
+			{
+				do_rake = true;
+				for (j = 0; j < 2; j++) {
+					BKE_curve_forward_diff_tangent_bezier(
+					        pcp->bez.vec[1][j],
+					        pcp->bez.vec[2][j],
+					        pcp_next->bez.vec[0][j],
+					        pcp_next->bez.vec[1][j],
+					        tangents + j, PAINT_CURVE_NUM_SEGMENTS, sizeof(float[2]));
+				}
+			}
 
 			for (j = 0; j < PAINT_CURVE_NUM_SEGMENTS; j++) {
+				float rotation = 0.0f;
+				if (do_rake) {
+					normalize_v2_v2(&tangents[2 * j], &tangents[2 * j]);
+					rotation = atan2f(tangents[2 * j], tangents[2 * j + 1]);
+				}
+
 				if (!stroke->stroke_started) {
 					stroke->last_pressure = 1.0;
 					copy_v2_v2(stroke->last_mouse_position, data + 2 * j);
 					stroke->stroke_started = stroke->test_start(C, op, stroke->last_mouse_position);
 
 					if (stroke->stroke_started) {
+						paint_update_brush_rake_rotation(ups, br, rotation);
 						paint_brush_stroke_add_step(C, op, data + 2 * j, 1.0);
 						paint_line_strokes_spacing(C, op, stroke, spacing, &length_residue, data + 2 * j, data + 2 * (j + 1));
 					}
 				}
 				else {
+					paint_update_brush_rake_rotation(ups, br, rotation);
 					paint_line_strokes_spacing(C, op, stroke, spacing, &length_residue, data + 2 * j, data + 2 * (j + 1));
 				}
 			}