Sculpt: Sharpen Mesh Filter curvature smoothing and intensify details

This adds a curvature smoothing and intensify details properties to control
the result of the Sharpen Mesh Filter.

Curvature smoothing removes high frequency details from the precalculated
sharpen data, so the filter result has much smoother surfaces and cleaner
sharpen lines;

Intensify details displaces the vertices of creases and valleys in the direction
opposite to its neighbors average, so it intensifies high frequency details
in those areas, producing more noisy and sharp shapes:

Both this properties can be used in combination to achieve a good balance of
high and low frequency details depending on the shape and the desired result.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8447

1 files changed, 67 insertions, 1 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_filter_mesh.c b/source/blender/editors/sculpt_paint/sculpt_filter_mesh.c
index e9a98a17f8a..ba11988156c 100644
--- a/source/blender/editors/sculpt_paint/sculpt_filter_mesh.c
+++ b/source/blender/editors/sculpt_paint/sculpt_filter_mesh.c
@@ -132,6 +132,7 @@ void SCULPT_filter_cache_free(SculptSession *ss)
   MEM_SAFE_FREE(ss->filter_cache->automask);
   MEM_SAFE_FREE(ss->filter_cache->surface_smooth_laplacian_disp);
   MEM_SAFE_FREE(ss->filter_cache->sharpen_factor);
+  MEM_SAFE_FREE(ss->filter_cache->sharpen_detail_directions);
   MEM_SAFE_FREE(ss->filter_cache);
 }
 
@@ -356,6 +357,17 @@ static void mesh_filter_task_cb(void *__restrict userdata,
         mul_v3_v3fl(
             disp_avg, disp_avg, smooth_ratio * pow2f(ss->filter_cache->sharpen_factor[vd.index]));
         add_v3_v3v3(disp, disp_avg, disp_sharpen);
+
+        /* Intensify details. */
+        if (ss->filter_cache->sharpen_intensify_detail_strength > 0.0f) {
+          float detail_strength[3];
+          normal_short_to_float_v3(detail_strength, orig_data.no);
+          copy_v3_v3(detail_strength, ss->filter_cache->sharpen_detail_directions[vd.index]);
+          madd_v3_v3fl(disp,
+                       detail_strength,
+                       -ss->filter_cache->sharpen_intensify_detail_strength *
+                           ss->filter_cache->sharpen_factor[vd.index]);
+        }
         break;
       }
     }
@@ -388,8 +400,10 @@ static void mesh_filter_sharpen_init_factors(SculptSession *ss)
   for (int i = 0; i < totvert; i++) {
     float avg[3];
     SCULPT_neighbor_coords_average(ss, avg, i);
-    ss->filter_cache->sharpen_factor[i] = len_v3v3(avg, SCULPT_vertex_co_get(ss, i));
+    sub_v3_v3v3(ss->filter_cache->sharpen_detail_directions[i], avg, SCULPT_vertex_co_get(ss, i));
+    ss->filter_cache->sharpen_factor[i] = len_v3(ss->filter_cache->sharpen_detail_directions[i]);
   }
+
   float max_factor = 0.0f;
   for (int i = 0; i < totvert; i++) {
     if (ss->filter_cache->sharpen_factor[i] > max_factor) {
@@ -402,6 +416,31 @@ static void mesh_filter_sharpen_init_factors(SculptSession *ss)
     ss->filter_cache->sharpen_factor[i] *= max_factor;
     ss->filter_cache->sharpen_factor[i] = 1.0f - pow2f(1.0f - ss->filter_cache->sharpen_factor[i]);
   }
+
+  /* Smooth the calculated factors and directions to remove high frecuency detail. */
+  for (int smooth_iterations = 0;
+       smooth_iterations < ss->filter_cache->sharpen_curvature_smooth_iterations;
+       smooth_iterations++) {
+    for (int i = 0; i < totvert; i++) {
+      float direction_avg[3] = {0.0f, 0.0f, 0.0f};
+      float sharpen_avg = 0;
+      int total = 0;
+
+      SculptVertexNeighborIter ni;
+      SCULPT_VERTEX_NEIGHBORS_ITER_BEGIN (ss, i, ni) {
+        add_v3_v3(direction_avg, ss->filter_cache->sharpen_detail_directions[ni.index]);
+        sharpen_avg += ss->filter_cache->sharpen_factor[ni.index];
+        total++;
+      }
+      SCULPT_VERTEX_NEIGHBORS_ITER_END(ni);
+
+      if (total > 0) {
+        mul_v3_v3fl(
+            ss->filter_cache->sharpen_detail_directions[i], direction_avg, 1.0f / (float)total);
+        ss->filter_cache->sharpen_factor[i] = sharpen_avg / (float)total;
+      }
+    }
+  }
 }
 
 static void mesh_filter_surface_smooth_displace_task_cb(
@@ -566,7 +605,14 @@ static int sculpt_mesh_filter_invoke(bContext *C, wmOperator *op, const wmEvent
 
   if (RNA_enum_get(op->ptr, "type") == MESH_FILTER_SHARPEN) {
     ss->filter_cache->sharpen_smooth_ratio = RNA_float_get(op->ptr, "sharpen_smooth_ratio");
+    ss->filter_cache->sharpen_intensify_detail_strength = RNA_float_get(
+        op->ptr, "sharpen_intensify_detail_strength");
+    ss->filter_cache->sharpen_curvature_smooth_iterations = RNA_int_get(
+        op->ptr, "sharpen_curvature_smooth_iterations");
+
     ss->filter_cache->sharpen_factor = MEM_mallocN(sizeof(float) * totvert, "sharpen factor");
+    ss->filter_cache->sharpen_detail_directions = MEM_malloc_arrayN(
+        totvert, 3 * sizeof(float), "sharpen detail direction");
 
     mesh_filter_sharpen_init_factors(ss);
   }
@@ -642,4 +688,24 @@ void SCULPT_OT_mesh_filter(struct wmOperatorType *ot)
                 "How much smoothing is applied to polished surfaces",
                 0.0f,
                 1.0f);
+
+  RNA_def_float(ot->srna,
+                "sharpen_intensify_detail_strength",
+                0.0f,
+                0.0f,
+                10.0f,
+                "Intensify Details",
+                "How much creases and valleys are intensified",
+                0.0f,
+                1.0f);
+
+  RNA_def_int(ot->srna,
+              "sharpen_curvature_smooth_iterations",
+              0,
+              0,
+              10,
+              "Curvature Smooth Iterations",
+              "How much smooth the resulting shape is, ignoring high frequency details",
+              0,
+              10);
 }