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

1 files changed, 31 insertions, 5 deletions

diff --git a/intern/cycles/render/scene.h b/intern/cycles/render/scene.h
index 5f717e93b43..ea9485ff230 100644
--- a/intern/cycles/render/scene.h
+++ b/intern/cycles/render/scene.h
@@ -17,6 +17,8 @@
 #ifndef __SCENE_H__
 #define __SCENE_H__
 
+#include "bvh/bvh_params.h"
+
 #include "render/image.h"
 #include "render/shader.h"
 
@@ -122,39 +124,63 @@ public:
 
 class SceneParams {
 public:
-	ShadingSystem shadingsystem;
+	/* Type of BVH, in terms whether it is supported dynamic updates of meshes
+	 * or whether modifying geometry requires full BVH rebuild.
+	 */
 	enum BVHType {
+		/* BVH supports dynamic updates of geometry.
+		 *
+		 * Faster for updating BVH tree when doing modifications in viewport,
+		 * but slower for rendering.
+		 */
 		BVH_DYNAMIC = 0,
+		/* BVH tree is calculated for specific scene, updates in geometry
+		 * requires full tree rebuild.
+		 *
+		 * Slower to update BVH tree when modifying objects in viewport, also
+		 * slower to build final BVH tree but gives best possible render speed.
+		 */
 		BVH_STATIC = 1,
 
 		BVH_NUM_TYPES,
-	} bvh_type;
+	};
+
+	ShadingSystem shadingsystem;
+
+	/* Requested BVH layout.
+	 *
+	 * If it's not supported by the device, the widest one from supported ones
+	 * will be used, but BVH wider than this one will never be used.
+	 */
+	BVHLayout bvh_layout;
+
+	BVHType bvh_type;
 	bool use_bvh_spatial_split;
 	bool use_bvh_unaligned_nodes;
 	int num_bvh_time_steps;
-	bool use_qbvh;
+
 	bool persistent_data;
 	int texture_limit;
 
 	SceneParams()
 	{
 		shadingsystem = SHADINGSYSTEM_SVM;
+		bvh_layout = BVH_LAYOUT_BVH2;
 		bvh_type = BVH_DYNAMIC;
 		use_bvh_spatial_split = false;
 		use_bvh_unaligned_nodes = true;
 		num_bvh_time_steps = 0;
-		use_qbvh = true;
 		persistent_data = false;
 		texture_limit = 0;
 	}
 
 	bool modified(const SceneParams& params)
 	{ return !(shadingsystem == params.shadingsystem
+		&& bvh_layout == params.bvh_layout
 		&& bvh_type == params.bvh_type
 		&& use_bvh_spatial_split == params.use_bvh_spatial_split
 		&& use_bvh_unaligned_nodes == params.use_bvh_unaligned_nodes
 		&& num_bvh_time_steps == params.num_bvh_time_steps
-		&& use_qbvh == params.use_qbvh
 		&& persistent_data == params.persistent_data
 		&& texture_limit == params.texture_limit); }
 };