Sculpt: only update draw buffers for visible nodes during paint stroke

Also applies to some other sculpt tools like filter and mask expand.

The full update happens after the paint stroke is finished, so it does not
happen on view navigation, which would cause a delay.

Ref T70295

Differential Revision: https://developer.blender.org/D5922

3 files changed, 30 insertions, 10 deletions

diff --git a/source/blender/blenkernel/BKE_pbvh.h b/source/blender/blenkernel/BKE_pbvh.h
index fa773ce78d9..426f81d889a 100644
--- a/source/blender/blenkernel/BKE_pbvh.h
+++ b/source/blender/blenkernel/BKE_pbvh.h
@@ -174,6 +174,7 @@ bool BKE_pbvh_node_find_nearest_to_ray(PBVH *bvh,
 
 void BKE_pbvh_draw_cb(PBVH *bvh,
                       bool show_vcol,
+                      bool update_only_visible,
                       PBVHFrustumPlanes *frustum,
                       void (*draw_fn)(void *user_data, struct GPU_PBVH_Buffers *buffers),
                       void *user_data);
diff --git a/source/blender/blenkernel/intern/pbvh.c b/source/blender/blenkernel/intern/pbvh.c
index 50ea4fb0b36..781e7b712d6 100644
--- a/source/blender/blenkernel/intern/pbvh.c
+++ b/source/blender/blenkernel/intern/pbvh.c
@@ -2287,6 +2287,7 @@ void BKE_pbvh_update_normals(PBVH *bvh, struct SubdivCCG *subdiv_ccg)
  */
 typedef struct PBVHDrawSearchData {
   PBVHFrustumPlanes *frustum;
+  int accum_update_flag;
 } PBVHDrawSearchData;
 
 static bool pbvh_draw_search_cb(PBVHNode *node, void *data_v)
@@ -2296,11 +2297,13 @@ static bool pbvh_draw_search_cb(PBVHNode *node, void *data_v)
     return false;
   }
 
+  data->accum_update_flag |= node->flag;
   return true;
 }
 
 void BKE_pbvh_draw_cb(PBVH *bvh,
                       bool show_vcol,
+                      bool update_only_visible,
                       PBVHFrustumPlanes *frustum,
                       void (*draw_fn)(void *user_data, GPU_PBVH_Buffers *buffers),
                       void *user_data)
@@ -2308,22 +2311,30 @@ void BKE_pbvh_draw_cb(PBVH *bvh,
   PBVHNode **nodes;
   int totnode;
 
-  /* Update all draw buffers. */
   const int update_flag = PBVH_RebuildDrawBuffers | PBVH_UpdateDrawBuffers;
-  BKE_pbvh_search_gather(bvh, update_search_cb, POINTER_FROM_INT(update_flag), &nodes, &totnode);
 
-  if (totnode) {
-    pbvh_update_draw_buffers(bvh, nodes, totnode, show_vcol, update_flag);
-  }
+  if (!update_only_visible) {
+    /* Update all draw buffers, also those outside the view. */
+    BKE_pbvh_search_gather(bvh, update_search_cb, POINTER_FROM_INT(update_flag), &nodes, &totnode);
 
-  if (nodes) {
-    MEM_freeN(nodes);
+    if (totnode) {
+      pbvh_update_draw_buffers(bvh, nodes, totnode, show_vcol, update_flag);
+    }
+
+    if (nodes) {
+      MEM_freeN(nodes);
+    }
   }
 
   /* Gather visible nodes. */
-  PBVHDrawSearchData data = {.frustum = frustum};
+  PBVHDrawSearchData data = {.frustum = frustum, .accum_update_flag = 0};
   BKE_pbvh_search_gather(bvh, pbvh_draw_search_cb, &data, &nodes, &totnode);
 
+  if (update_only_visible && (data.accum_update_flag & update_flag)) {
+    /* Update draw buffers in visible nodes. */
+    pbvh_update_draw_buffers(bvh, nodes, totnode, show_vcol, data.accum_update_flag);
+  }
+
   /* Draw. */
   for (int a = 0; a < totnode; a++) {
     PBVHNode *node = nodes[a];
diff --git a/source/blender/draw/intern/draw_manager_data.c b/source/blender/draw/intern/draw_manager_data.c
index e978ae44bcd..e3d4228ec33 100644
--- a/source/blender/draw/intern/draw_manager_data.c
+++ b/source/blender/draw/intern/draw_manager_data.c
@@ -923,11 +923,19 @@ static void drw_sculpt_generate_calls(DRWSculptCallbackData *scd, bool use_vcol)
     }
   }
 
+  /* Update draw buffers only for visible nodes while painting.
+   * But do update them otherwise so navigating stays smooth. */
+  const bool update_only_visible = rv3d && (rv3d->rflag & RV3D_PAINTING);
+
   Mesh *mesh = scd->ob->data;
   BKE_pbvh_update_normals(pbvh, mesh->runtime.subdiv_ccg);
 
-  BKE_pbvh_draw_cb(
-      pbvh, use_vcol, &frustum, (void (*)(void *, GPU_PBVH_Buffers *))sculpt_draw_cb, scd);
+  BKE_pbvh_draw_cb(pbvh,
+                   use_vcol,
+                   update_only_visible,
+                   &frustum,
+                   (void (*)(void *, GPU_PBVH_Buffers *))sculpt_draw_cb,
+                   scd);
 
   if (SCULPT_DEBUG_BUFFERS) {
     int debug_node_nr = 0;