Cycles: Replace use_qbvh boolean flag with an enum-based property

This was we can introduce other types of BVH, for example, wider ones, without
causing too much mess around boolean flags.

Thoughs:

- Ideally device info should probably return bitflag of what BVH types it
  supports.

  It is possible to implement based on simple logic in device/ and mesh.cpp,
  rest of the changes will stay the same.

- Not happy with workarounds in util_debug and duplicated enum in kernel.
  Maybe enbum should be stores in kernel, but then it's kind of weird to include
  kernel types from utils. Soudns some cyclkic dependency.

Reviewers: brecht, maxim_d33

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D3011

4 files changed, 13 insertions, 4 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index 7410cc32342..a63d84f2da6 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -47,6 +47,11 @@ enum_displacement_methods = (
     ('BOTH', "Both", "Combination of displacement and bump mapping"),
     )
 
+enum_bvh_layouts = (
+    ('BVH2', "BVH2", "", 1),
+    ('BVH4', "BVH4", "", 2),
+    )
+
 enum_bvh_types = (
     ('DYNAMIC_BVH', "Dynamic BVH", "Objects can be individually updated, at the cost of slower render time"),
     ('STATIC_BVH', "Static BVH", "Any object modification requires a complete BVH rebuild, but renders faster"),
@@ -670,7 +675,11 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
         cls.debug_use_cpu_sse41 = BoolProperty(name="SSE41", default=True)
         cls.debug_use_cpu_sse3 = BoolProperty(name="SSE3", default=True)
         cls.debug_use_cpu_sse2 = BoolProperty(name="SSE2", default=True)
-        cls.debug_use_qbvh = BoolProperty(name="QBVH", default=True)
+        cls.debug_bvh_layout = EnumProperty(
+                name="BVH Layout",
+                items=enum_bvh_layouts,
+                default='BVH4',
+                )
         cls.debug_use_cpu_split_kernel = BoolProperty(name="Split Kernel", default=False)
 
         cls.debug_use_cuda_adaptive_compile = BoolProperty(name="Adaptive Compile", default=False)
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 5d58ecc99eb..543ba7c6d4d 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -1609,7 +1609,7 @@ class CYCLES_RENDER_PT_debug(CyclesButtonsPanel, Panel):
         row.prop(cscene, "debug_use_cpu_sse41", toggle=True)
         row.prop(cscene, "debug_use_cpu_avx", toggle=True)
         row.prop(cscene, "debug_use_cpu_avx2", toggle=True)
-        col.prop(cscene, "debug_use_qbvh")
+        col.prop(cscene, "debug_bvh_layout")
         col.prop(cscene, "debug_use_cpu_split_kernel")
 
         col.separator()
diff --git a/intern/cycles/blender/blender_python.cpp b/intern/cycles/blender/blender_python.cpp
index 687ddd9e7c3..792597cbad5 100644
--- a/intern/cycles/blender/blender_python.cpp
+++ b/intern/cycles/blender/blender_python.cpp
@@ -69,7 +69,7 @@ bool debug_flags_sync_from_scene(BL::Scene b_scene)
 	flags.cpu.sse41 = get_boolean(cscene, "debug_use_cpu_sse41");
 	flags.cpu.sse3 = get_boolean(cscene, "debug_use_cpu_sse3");
 	flags.cpu.sse2 = get_boolean(cscene, "debug_use_cpu_sse2");
-	flags.cpu.qbvh = get_boolean(cscene, "debug_use_qbvh");
+	flags.cpu.bvh_layout = (BVHLayout)get_enum(cscene, "debug_bvh_layout");
 	flags.cpu.split_kernel = get_boolean(cscene, "debug_use_cpu_split_kernel");
 	/* Synchronize CUDA flags. */
 	flags.cuda.adaptive_compile = get_boolean(cscene, "debug_use_cuda_adaptive_compile");
diff --git a/intern/cycles/blender/blender_sync.cpp b/intern/cycles/blender/blender_sync.cpp
index b7c6fbc9d29..283aa5600fd 100644
--- a/intern/cycles/blender/blender_sync.cpp
+++ b/intern/cycles/blender/blender_sync.cpp
@@ -662,7 +662,7 @@ SceneParams BlenderSync::get_scene_params(BL::Scene& b_scene,
 		params.texture_limit = 0;
 	}
 
-	params.use_qbvh = DebugFlags().cpu.qbvh;
+	params.bvh_layout = DebugFlags().cpu.bvh_layout;
 
 	return params;
 }