Dynamic Paint: Added a new "smoothness" parameter for waves.

It greatly helps getting rid of that "noise" that occurs if you use really steep objects (like cubes) as a brush. New default value is 1.0 which is just high enough to only get rid of the sharpest spikes, so if you want really smooth waves it's better use higher values.

This also seems to "fix" bug [#35413].

release/scripts/startup/bl_ui/properties_physics_dynamicpaint.py

@@ -201,6 +201,7 @@ class PHYSICS_PT_dp_advanced_canvas(PhysicButtonsPanel, Panel):
             col = split.column(align=True)
             col.prop(surface, "wave_damping")
             col.prop(surface, "wave_spring")
+            col.prop(surface, "wave_smoothness")
 
         layout.separator()
         layout.prop(surface, "brush_group")

source/blender/blenkernel/intern/dynamicpaint.c

@@ -1078,6 +1078,7 @@ DynamicPaintSurface *dynamicPaint_createNewSurface(DynamicPaintCanvasSettings *c
 	surface->wave_speed = 1.0f;
 	surface->wave_timescale = 1.0f;
 	surface->wave_spring = 0.20f;
+	surface->wave_smoothness = 1.0f;
 
 	modifier_path_init(surface->image_output_path, sizeof(surface->image_output_path), "cache_dynamicpaint");
 
@@ -1253,6 +1254,7 @@ void dynamicPaint_Modifier_copy(struct DynamicPaintModifierData *pmd, struct Dyn
 			t_surface->wave_speed = surface->wave_speed;
 			t_surface->wave_timescale = surface->wave_timescale;
 			t_surface->wave_spring = surface->wave_spring;
+			t_surface->wave_smoothness = surface->wave_smoothness;
 
 			BLI_strncpy(t_surface->uvlayer_name, surface->uvlayer_name, sizeof(t_surface->uvlayer_name));
 			BLI_strncpy(t_surface->image_output_path, surface->image_output_path, sizeof(t_surface->image_output_path));
@@ -4465,6 +4467,7 @@ static void dynamicPaint_doWaveStep(DynamicPaintSurface *surface, float timescal
 	int steps, ss;
 	float dt, min_dist, damp_factor;
 	float wave_speed = surface->wave_speed;
+	float wave_max_slope = (surface->wave_smoothness >= 0.01f) ? (0.5f / surface->wave_smoothness) : 0.0f;
 	double average_dist = 0.0f;
 	const float canvas_size = getSurfaceDimension(sData);
 	float wave_scale = CANVAS_REL_SIZE / canvas_size;
@@ -4503,7 +4506,7 @@ static void dynamicPaint_doWaveStep(DynamicPaintSurface *surface, float timescal
 		for (index = 0; index < sData->total_points; index++) {
 			PaintWavePoint *wPoint = &((PaintWavePoint *)sData->type_data)[index];
 			int numOfNeighs = sData->adj_data->n_num[index];
-			float force = 0.0f, avg_dist = 0.0f, avg_height = 0.0f;
+			float force = 0.0f, avg_dist = 0.0f, avg_height = 0.0f, avg_n_height = 0.0f;
 			int numOfN = 0, numOfRN = 0;
 			int i;
 
@@ -4522,11 +4525,12 @@ static void dynamicPaint_doWaveStep(DynamicPaintSurface *surface, float timescal
 
 				/* count average height for edge points for open borders */
 				if (!(sData->adj_data->flags[sData->adj_data->n_target[n_index]] & ADJ_ON_MESH_EDGE)) {
-					avg_height += tPoint->height;
+					avg_n_height += tPoint->height;
 					numOfRN++;
 				}
 
 				force += (tPoint->height - wPoint->height) / (dist * dist);
+				avg_height += tPoint->height;
 			}
 			avg_dist = (numOfN) ? avg_dist / numOfN : 0.0f;
 
@@ -4534,8 +4538,8 @@ static void dynamicPaint_doWaveStep(DynamicPaintSurface *surface, float timescal
 			    sData->adj_data->flags[index] & ADJ_ON_MESH_EDGE)
 			{
 				/* if open borders, apply a fake height to keep waves going on */
-				avg_height = (numOfRN) ? avg_height / numOfRN : 0.0f;
-				wPoint->height = (dt * wave_speed * avg_height + wPoint->height * avg_dist) / (avg_dist + dt * wave_speed);
+				avg_n_height = (numOfRN) ? avg_n_height / numOfRN : 0.0f;
+				wPoint->height = (dt * wave_speed * avg_n_height + wPoint->height * avg_dist) / (avg_dist + dt * wave_speed);
 			}
 			/* else do wave eq */
 			else {
@@ -4549,6 +4553,14 @@ static void dynamicPaint_doWaveStep(DynamicPaintSurface *surface, float timescal
 				wPoint->velocity *= damp_factor;
 				/* and new height */
 				wPoint->height += wPoint->velocity * dt;
+
+				/* limit wave slope steepness */
+				if (wave_max_slope && avg_dist) {
+					float max_offset = wave_max_slope * avg_dist;
+					float offset = (numOfN) ? (avg_height / numOfN - wPoint->height) : 0.0f;
+					if (offset > max_offset) wPoint->height += offset - max_offset;
+					if (offset < -max_offset) wPoint->height += offset + max_offset;
+				}
 			}
 		}
 	}

source/blender/makesdna/DNA_dynamicpaint_types.h

@@ -125,7 +125,8 @@ typedef struct DynamicPaintSurface {
 	float influence_scale, radius_scale;
 
 	/* wave settings */
-	float wave_damping, wave_speed, wave_timescale, wave_spring;
+	float wave_damping, wave_speed, wave_timescale, wave_spring, wave_smoothness;
+	int pad2;
 
 	char uvlayer_name[64];	/* MAX_CUSTOMDATA_LAYER_NAME */
 	char image_output_path[1024];  /* 1024 = FILE_MAX */

source/blender/makesrna/intern/rna_dynamicpaint.c

@@ -710,6 +710,11 @@ static void rna_def_canvas_surface(BlenderRNA *brna)
 	RNA_def_property_ui_range(prop, 0.01, 1.0, 1, 2);
 	RNA_def_property_ui_text(prop, "Spring", "Spring force that pulls water level back to zero");
 
+	prop = RNA_def_property(srna, "wave_smoothness", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_range(prop, 0.0, 10.0);
+	RNA_def_property_ui_range(prop, 0.1, 5.0, 1, 2);
+	RNA_def_property_ui_text(prop, "Smoothness", "Limit maximum steepness of wave slope between simulation points. Use higher values for smoother waves at expense of reduced detail");
+
 	prop = RNA_def_property(srna, "use_wave_open_border", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "flags", MOD_DPAINT_WAVE_OPEN_BORDERS);
 	RNA_def_property_ui_text(prop, "Open Borders", "Pass waves through mesh edges");