/*
 * Adapted from code copyright 2009-2010 NVIDIA Corporation
 * Modifications Copyright 2011, Blender Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef __BVH_H__
#define __BVH_H__

#include "bvh_params.h"

#include "util_types.h"
#include "util_vector.h"

CCL_NAMESPACE_BEGIN

class BVHNode;
struct BVHStackEntry;
class BVHParams;
class BoundBox;
class LeafNode;
class Object;
class Progress;

#define BVH_NODE_SIZE	4
#define BVH_NODE_LEAF_SIZE	1
#define BVH_QNODE_SIZE	8
#define BVH_QNODE_LEAF_SIZE	1
#define BVH_ALIGN		4096
#define TRI_NODE_SIZE	3

#define BVH_UNALIGNED_NODE_SIZE 7
#define BVH_UNALIGNED_QNODE_SIZE 14

/* Packed BVH
 *
 * BVH stored as it will be used for traversal on the rendering device. */

struct PackedBVH {
	/* BVH nodes storage, one node is 4x int4, and contains two bounding boxes,
	 * and child, triangle or object indexes depending on the node type */
	array<int4> nodes;
	/* BVH leaf nodes storage. */
	array<int4> leaf_nodes;
	/* object index to BVH node index mapping for instances */
	array<int> object_node; 
	/* Mapping from primitive index to index in triangle array. */
	array<uint> prim_tri_index;
	/* Continuous storage of triangle vertices. */
	array<float4> prim_tri_verts;
	/* primitive type - triangle or strand */
	array<int> prim_type;
	/* visibility visibilitys for primitives */
	array<uint> prim_visibility;
	/* mapping from BVH primitive index to true primitive index, as primitives
	 * may be duplicated due to spatial splits. -1 for instances. */
	array<int> prim_index;
	/* mapping from BVH primitive index, to the object id of that primitive. */
	array<int> prim_object;

	/* index of the root node. */
	int root_index;

	PackedBVH()
	{
		root_index = 0;
	}
};

/* BVH */

class BVH
{
public:
	PackedBVH pack;
	BVHParams params;
	vector<Object*> objects;

	static BVH *create(const BVHParams& params, const vector<Object*>& objects);
	virtual ~BVH() {}

	void build(Progress& progress);
	void refit(Progress& progress);

protected:
	BVH(const BVHParams& params, const vector<Object*>& objects);

	/* triangles and strands */
	void pack_primitives();
	void pack_triangle(int idx, float4 storage[3]);

	/* merge instance BVH's */
	void pack_instances(size_t nodes_size, size_t leaf_nodes_size);

	/* for subclasses to implement */
	virtual void pack_nodes(const BVHNode *root) = 0;
	virtual void refit_nodes() = 0;
};

/* Regular BVH
 *
 * Typical BVH with each node having two children. */

class RegularBVH : public BVH {
protected:
	/* constructor */
	friend class BVH;
	RegularBVH(const BVHParams& params, const vector<Object*>& objects);

	/* pack */
	void pack_nodes(const BVHNode *root);

	void pack_leaf(const BVHStackEntry& e,
	               const LeafNode *leaf);
	void pack_inner(const BVHStackEntry& e,
	                const BVHStackEntry& e0,
	                const BVHStackEntry& e1);

	void pack_aligned_inner(const BVHStackEntry& e,
	                        const BVHStackEntry& e0,
	                        const BVHStackEntry& e1);
	void pack_aligned_node(int idx,
	                       const BoundBox& b0,
	                       const BoundBox& b1,
	                       int c0, int c1,
	                       uint visibility0, uint visibility1);

	void pack_unaligned_inner(const BVHStackEntry& e,
	                          const BVHStackEntry& e0,
	                          const BVHStackEntry& e1);
	void pack_unaligned_node(int idx,
	                         const Transform& aligned_space0,
	                         const Transform& aligned_space1,
	                         const BoundBox& b0,
	                         const BoundBox& b1,
	                         int c0, int c1,
	                         uint visibility0, uint visibility1);

	/* refit */
	void refit_nodes();
	void refit_node(int idx, bool leaf, BoundBox& bbox, uint& visibility);
};

/* QBVH
 *
 * Quad BVH, with each node having four children, to use with SIMD instructions. */

class QBVH : public BVH {
protected:
	/* constructor */
	friend class BVH;
	QBVH(const BVHParams& params, const vector<Object*>& objects);

	/* pack */
	void pack_nodes(const BVHNode *root);

	void pack_leaf(const BVHStackEntry& e, const LeafNode *leaf);
	void pack_inner(const BVHStackEntry& e, const BVHStackEntry *en, int num);

	void pack_aligned_inner(const BVHStackEntry& e,
	                        const BVHStackEntry *en,
	                        int num);
	void pack_aligned_node(int idx,
	                       const BoundBox *bounds,
	                       const int *child,
	                       const uint visibility,
	                       const float time_from,
	                       const float time_to,
	                       const int num);

	void pack_unaligned_inner(const BVHStackEntry& e,
	                          const BVHStackEntry *en,
	                          int num);
	void pack_unaligned_node(int idx,
	                         const Transform *aligned_space,
	                         const BoundBox *bounds,
	                         const int *child,
	                         const uint visibility,
	                         const float time_from,
	                         const float time_to,
	                         const int num);

	/* refit */
	void refit_nodes();
	void refit_node(int idx, bool leaf, BoundBox& bbox, uint& visibility);
};

CCL_NAMESPACE_END

#endif /* __BVH_H__ */