Integrate hair collisions with cloth collision

This integrates hair collisions with the new cloth collision system,
greatly improving reliability, and reducing the amount of hair-specific
code paths in the cloth code.

The removes all the point constraint based collision stuff, instead
implementing segment impulse based collisions, using the same collision
response code as the normal cloth solver.

The hair system can now also collide with the emitter if it is a
collision object.

Reviewed By: mano-wii, Sebastian Parborg

Differential Revision: https://developer.blender.org/D6545

1 files changed, 81 insertions, 37 deletions

diff --git a/source/blender/blenkernel/intern/cloth.c b/source/blender/blenkernel/intern/cloth.c
index c26800aefba..7332c3e0d43 100644
--- a/source/blender/blenkernel/intern/cloth.c
+++ b/source/blender/blenkernel/intern/cloth.c
@@ -190,22 +190,36 @@ static BVHTree *bvhtree_build_from_cloth(ClothModifierData *clmd, float epsilon)
   vt = cloth->tri;
 
   /* in the moment, return zero if no faces there */
-  if (!cloth->tri_num) {
+  if (!cloth->primitive_num) {
     return NULL;
   }
 
   /* create quadtree with k=26 */
-  bvhtree = BLI_bvhtree_new(cloth->tri_num, epsilon, 4, 26);
+  bvhtree = BLI_bvhtree_new(cloth->primitive_num, epsilon, 4, 26);
 
   /* fill tree */
-  for (i = 0; i < cloth->tri_num; i++, vt++) {
-    float co[3][3];
+  if (clmd->hairdata == NULL) {
+    for (i = 0; i < cloth->primitive_num; i++, vt++) {
+      float co[3][3];
 
-    copy_v3_v3(co[0], verts[vt->tri[0]].xold);
-    copy_v3_v3(co[1], verts[vt->tri[1]].xold);
-    copy_v3_v3(co[2], verts[vt->tri[2]].xold);
+      copy_v3_v3(co[0], verts[vt->tri[0]].xold);
+      copy_v3_v3(co[1], verts[vt->tri[1]].xold);
+      copy_v3_v3(co[2], verts[vt->tri[2]].xold);
 
-    BLI_bvhtree_insert(bvhtree, i, co[0], 3);
+      BLI_bvhtree_insert(bvhtree, i, co[0], 3);
+    }
+  }
+  else {
+    MEdge *edges = cloth->edges;
+
+    for (i = 0; i < cloth->primitive_num; i++) {
+      float co[2][3];
+
+      copy_v3_v3(co[0], verts[edges[i].v1].xold);
+      copy_v3_v3(co[1], verts[edges[i].v2].xold);
+
+      BLI_bvhtree_insert(bvhtree, i, co[0], 2);
+    }
   }
 
   /* balance tree */
@@ -222,6 +236,8 @@ void bvhtree_update_from_cloth(ClothModifierData *clmd, bool moving, bool self)
   ClothVertex *verts = cloth->verts;
   const MVertTri *vt;
 
+  BLI_assert(!(clmd->hairdata != NULL && self));
+
   if (self) {
     bvhtree = cloth->bvhselftree;
   }
@@ -236,39 +252,59 @@ void bvhtree_update_from_cloth(ClothModifierData *clmd, bool moving, bool self)
   vt = cloth->tri;
 
   /* update vertex position in bvh tree */
-  if (verts && vt) {
-    for (i = 0; i < cloth->tri_num; i++, vt++) {
-      float co[3][3], co_moving[3][3];
-      bool ret;
-
-      /* copy new locations into array */
-      if (moving) {
-        copy_v3_v3(co[0], verts[vt->tri[0]].txold);
-        copy_v3_v3(co[1], verts[vt->tri[1]].txold);
-        copy_v3_v3(co[2], verts[vt->tri[2]].txold);
-
-        /* update moving positions */
-        copy_v3_v3(co_moving[0], verts[vt->tri[0]].tx);
-        copy_v3_v3(co_moving[1], verts[vt->tri[1]].tx);
-        copy_v3_v3(co_moving[2], verts[vt->tri[2]].tx);
-
-        ret = BLI_bvhtree_update_node(bvhtree, i, co[0], co_moving[0], 3);
-      }
-      else {
-        copy_v3_v3(co[0], verts[vt->tri[0]].tx);
-        copy_v3_v3(co[1], verts[vt->tri[1]].tx);
-        copy_v3_v3(co[2], verts[vt->tri[2]].tx);
+  if (clmd->hairdata == NULL) {
+    if (verts && vt) {
+      for (i = 0; i < cloth->primitive_num; i++, vt++) {
+        float co[3][3], co_moving[3][3];
+        bool ret;
+
+        /* copy new locations into array */
+        if (moving) {
+          copy_v3_v3(co[0], verts[vt->tri[0]].txold);
+          copy_v3_v3(co[1], verts[vt->tri[1]].txold);
+          copy_v3_v3(co[2], verts[vt->tri[2]].txold);
+
+          /* update moving positions */
+          copy_v3_v3(co_moving[0], verts[vt->tri[0]].tx);
+          copy_v3_v3(co_moving[1], verts[vt->tri[1]].tx);
+          copy_v3_v3(co_moving[2], verts[vt->tri[2]].tx);
+
+          ret = BLI_bvhtree_update_node(bvhtree, i, co[0], co_moving[0], 3);
+        }
+        else {
+          copy_v3_v3(co[0], verts[vt->tri[0]].tx);
+          copy_v3_v3(co[1], verts[vt->tri[1]].tx);
+          copy_v3_v3(co[2], verts[vt->tri[2]].tx);
 
-        ret = BLI_bvhtree_update_node(bvhtree, i, co[0], NULL, 3);
-      }
+          ret = BLI_bvhtree_update_node(bvhtree, i, co[0], NULL, 3);
+        }
 
-      /* check if tree is already full */
-      if (ret == false) {
-        break;
+        /* check if tree is already full */
+        if (ret == false) {
+          break;
+        }
       }
+
+      BLI_bvhtree_update_tree(bvhtree);
     }
+  }
+  else {
+    if (verts) {
+      MEdge *edges = cloth->edges;
+
+      for (i = 0; i < cloth->primitive_num; i++) {
+        float co[2][3];
 
-    BLI_bvhtree_update_tree(bvhtree);
+        copy_v3_v3(co[0], verts[edges[i].v1].tx);
+        copy_v3_v3(co[1], verts[edges[i].v2].tx);
+
+        if (!BLI_bvhtree_update_node(bvhtree, i, co[0], NULL, 2)) {
+          break;
+        }
+      }
+
+      BLI_bvhtree_update_tree(bvhtree);
+    }
   }
 }
 
@@ -900,7 +936,13 @@ static void cloth_from_mesh(ClothModifierData *clmd, Mesh *mesh)
   }
 
   /* save face information */
-  clmd->clothObject->tri_num = looptri_num;
+  if (clmd->hairdata == NULL) {
+    clmd->clothObject->primitive_num = looptri_num;
+  }
+  else {
+    clmd->clothObject->primitive_num = mesh->totedge;
+  }
+
   clmd->clothObject->tri = MEM_mallocN(sizeof(MVertTri) * looptri_num, "clothLoopTris");
   if (clmd->clothObject->tri == NULL) {
     cloth_free_modifier(clmd);
@@ -910,6 +952,8 @@ static void cloth_from_mesh(ClothModifierData *clmd, Mesh *mesh)
   }
   BKE_mesh_runtime_verttri_from_looptri(clmd->clothObject->tri, mloop, looptri, looptri_num);
 
+  clmd->clothObject->edges = mesh->medge;
+
   /* Free the springs since they can't be correct if the vertices
    * changed.
    */