Sculpt: Fix creation of repeated constraints in the Cloth Brush

Previously, constraints were added multiple times from different
vertices. This adds a GSet to check that the same constraint is not
being added twice when iterating over the neighbors of two different
vertices.

Reviewed By: zeddb

Differential Revision: https://developer.blender.org/D8007

2 files changed, 35 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index 4d30c5c7fce..144e091d971 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -24,6 +24,7 @@
  * \ingroup bke
  */
 
+#include "BLI_ghash.h"
 #include "BLI_utildefines.h"
 #include "DNA_object_enums.h"
 
@@ -268,6 +269,7 @@ typedef struct SculptClothLengthConstraint {
 typedef struct SculptClothSimulation {
   SculptClothLengthConstraint *length_constraints;
   int tot_length_constraints;
+  GSet *created_length_constraints;
   int capacity_length_constraints;
   float *length_constraint_tweak;
 
diff --git a/source/blender/editors/sculpt_paint/sculpt_cloth.c b/source/blender/editors/sculpt_paint/sculpt_cloth.c
index 3203282c30c..7776af11a77 100644
--- a/source/blender/editors/sculpt_paint/sculpt_cloth.c
+++ b/source/blender/editors/sculpt_paint/sculpt_cloth.c
@@ -106,6 +106,27 @@
 #define CLOTH_MAX_CONSTRAINTS_PER_VERTEX 1024
 #define CLOTH_SIMULATION_TIME_STEP 0.01f
 
+static void cloth_brush_constraint_key_get(int r_key[2], const int v1, const int v2)
+{
+  if (v1 < v2) {
+    r_key[0] = v1;
+    r_key[1] = v2;
+  }
+  else {
+    r_key[0] = v2;
+    r_key[1] = v1;
+  }
+}
+
+static bool cloth_brush_sim_has_length_constraint(SculptClothSimulation *cloth_sim,
+                                                  const int v1,
+                                                  const int v2)
+{
+  int constraint[2];
+  cloth_brush_constraint_key_get(constraint, v1, v2);
+  return BLI_gset_haskey(cloth_sim->created_length_constraints, constraint);
+}
+
 static void cloth_brush_add_length_constraint(SculptSession *ss,
                                               SculptClothSimulation *cloth_sim,
                                               const int v1,
@@ -126,6 +147,11 @@ static void cloth_brush_add_length_constraint(SculptSession *ss,
                                                         sizeof(SculptClothLengthConstraint),
                                                     "length constraints");
   }
+
+  /* Add the constraint to the GSet to avoid creating it again. */
+  int constraint[2];
+  cloth_brush_constraint_key_get(constraint, v1, v2);
+  BLI_gset_add(cloth_sim->created_length_constraints, constraint);
 }
 
 static void do_cloth_brush_build_constraints_task_cb_ex(
@@ -159,7 +185,8 @@ static void do_cloth_brush_build_constraints_task_cb_ex(
 
       for (int c_i = 0; c_i < tot_indices; c_i++) {
         for (int c_j = 0; c_j < tot_indices; c_j++) {
-          if (c_i != c_j) {
+          if (c_i != c_j && !cloth_brush_sim_has_length_constraint(
+                                data->cloth_sim, build_indices[c_i], build_indices[c_j])) {
             cloth_brush_add_length_constraint(
                 ss, data->cloth_sim, build_indices[c_i], build_indices[c_j]);
           }
@@ -445,6 +472,9 @@ static void cloth_brush_build_nodes_constraints(Sculpt *sd,
   TaskParallelSettings settings;
   BKE_pbvh_parallel_range_settings(&settings, false, totnode);
 
+  cloth_sim->created_length_constraints = BLI_gset_new(
+      BLI_ghashutil_inthash_v2_p, BLI_ghashutil_inthash_v2_cmp, "created length constraints");
+
   SculptThreadedTaskData build_constraints_data = {
       .sd = sd,
       .ob = ob,
@@ -456,6 +486,8 @@ static void cloth_brush_build_nodes_constraints(Sculpt *sd,
   };
   BLI_task_parallel_range(
       0, totnode, &build_constraints_data, do_cloth_brush_build_constraints_task_cb_ex, &settings);
+
+  BLI_gset_free(cloth_sim->created_length_constraints, NULL);
 }
 
 static void cloth_brush_satisfy_constraints(SculptSession *ss,