Cycles: Make Embree compact BVH optional

Make the Embree RTC_SCENE_FLAG_COMPACT flag optional and enabled per default.
Disabling it makes CPU rendering a bit faster in some scenes at the cost of a higher memory usage.

Barbershop renders about 3% faster, victor about 4% on CPU with compact BVH disabled.

Differential Revision: https://developer.blender.org/D13592

3 files changed, 8 insertions, 0 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index f669adb9f37..93a0717ad5f 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -667,6 +667,11 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
         description="Use special type BVH optimized for hair (uses more ram but renders faster)",
         default=True,
     )
+    debug_use_compact_bvh: BoolProperty(
+        name="Use Compact BVH",
+        description="Use compact BVH structure (uses less ram but renders slower)",
+        default=True,
+    )
     debug_bvh_time_steps: IntProperty(
         name="BVH Time Steps",
         description="Split BVH primitives by this number of time steps to speed up render time in cost of memory",
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 5b600692152..06cf69f90ca 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -689,6 +689,8 @@ class CYCLES_RENDER_PT_performance_acceleration_structure(CyclesButtonsPanel, Pa
         sub.active = not cscene.debug_use_spatial_splits and not use_embree
         sub.prop(cscene, "debug_bvh_time_steps")
 
+        col.prop(cscene, "debug_use_compact_bvh")
+
 
 class CYCLES_RENDER_PT_performance_final_render(CyclesButtonsPanel, Panel):
     bl_label = "Final Render"
diff --git a/intern/cycles/blender/sync.cpp b/intern/cycles/blender/sync.cpp
index 588e057b9ad..7e6f1535d66 100644
--- a/intern/cycles/blender/sync.cpp
+++ b/intern/cycles/blender/sync.cpp
@@ -787,6 +787,7 @@ SceneParams BlenderSync::get_scene_params(BL::Scene &b_scene, bool background)
     params.bvh_type = BVH_TYPE_DYNAMIC;
 
   params.use_bvh_spatial_split = RNA_boolean_get(&cscene, "debug_use_spatial_splits");
+  params.use_bvh_compact_structure = RNA_boolean_get(&cscene, "debug_use_compact_bvh");
   params.use_bvh_unaligned_nodes = RNA_boolean_get(&cscene, "debug_use_hair_bvh");
   params.num_bvh_time_steps = RNA_int_get(&cscene, "debug_bvh_time_steps");