From 5c01ecd2bf5d0dc0d42f90aba2a3d9f948d16bb8 Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brecht@blender.org>
Date: Wed, 11 Nov 2020 18:40:46 +0100
Subject: Fix T82516: Cycles crash updateding animated volumes after NanoVDB

Two issues:
* Automatic deduplication of OpenVDB grid data was failing when Cycles had
  already cleared the OpenVDB grid, causing an empty grid. Instead rely on
  Blender return the same OpenVDB grid pointer when deduplication is possible.
* The volume bounds mesh was not properly cleared when the OpenVDB grid was
  empty, causing a mismatch between mesh and voxel data.
---
 intern/cycles/blender/blender_volume.cpp | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

(limited to 'intern/cycles/blender/blender_volume.cpp')

diff --git a/intern/cycles/blender/blender_volume.cpp b/intern/cycles/blender/blender_volume.cpp
index e039d8a4895..48ae5a2c5ae 100644
--- a/intern/cycles/blender/blender_volume.cpp
+++ b/intern/cycles/blender/blender_volume.cpp
@@ -242,13 +242,6 @@ class BlenderVolumeLoader : public VDBImageLoader {
 #endif
   }
 
-  bool equals(const ImageLoader &other) const override
-  {
-    /* TODO: detect multiple volume datablocks with the same filepath. */
-    const BlenderVolumeLoader &other_loader = (const BlenderVolumeLoader &)other;
-    return b_volume == other_loader.b_volume && grid_name == other_loader.grid_name;
-  }
-
   BL::Volume b_volume;
 };
 
@@ -307,25 +300,10 @@ static void sync_volume_object(BL::BlendData &b_data,
   }
 }
 
-/* If the voxel attributes change, we need to rebuild the bounding mesh. */
-static vector<int> get_voxel_image_slots(Mesh *mesh)
-{
-  vector<int> slots;
-  for (const Attribute &attr : mesh->attributes.attributes) {
-    if (attr.element == ATTR_ELEMENT_VOXEL) {
-      slots.push_back(attr.data_voxel().svm_slot());
-    }
-  }
-
-  return slots;
-}
-
 void BlenderSync::sync_volume(BL::Object &b_ob,
                               Volume *volume,
                               const vector<Shader *> &used_shaders)
 {
-  vector<int> old_voxel_slots = get_voxel_image_slots(volume);
-
   volume->clear();
   volume->used_shaders = used_shaders;
 
@@ -342,8 +320,7 @@ void BlenderSync::sync_volume(BL::Object &b_ob,
   }
 
   /* Tag update. */
-  bool rebuild = (old_voxel_slots != get_voxel_image_slots(volume));
-  volume->tag_update(scene, rebuild);
+  volume->tag_update(scene, true);
 }
 
 CCL_NAMESPACE_END
-- 
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