/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version. 
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2009 Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): André Pinto.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/render/intern/raytrace/rayobject_vbvh.cpp
 *  \ingroup render
 */


int tot_pushup   = 0;
int tot_pushdown = 0;
int tot_hints    = 0;

#include <assert.h>

#include "MEM_guardedalloc.h"

#include "BLI_math.h"
#include "BLI_memarena.h"
#include "BLI_utildefines.h"

#include "BKE_global.h"

#include "rayintersection.h"
#include "rayobject.h"
#include "rayobject_rtbuild.h"

#include "reorganize.h"
#include "bvh.h"
#include "vbvh.h"

#include <queue>
#include <algorithm>

#define DFS_STACK_SIZE  256

struct VBVHTree {
	RayObject rayobj;
	VBVHNode *root;
	MemArena *node_arena;
	float cost;
	RTBuilder *builder;
};

/*
 * Cost to test N childs
 */
struct PackCost {
	float operator()(int n)
	{
		return n;
	}
};

template<>
void bvh_done<VBVHTree>(VBVHTree *obj)
{
	rtbuild_done(obj->builder, &obj->rayobj.control);
	
	//TODO find a away to exactly calculate the needed memory
	MemArena *arena1 = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, "vbvh arena");
	BLI_memarena_use_malloc(arena1);
	
	//Build and optimize the tree
	if (1) {
		VBVHNode *root = BuildBinaryVBVH<VBVHNode>(arena1, &obj->rayobj.control).transform(obj->builder);
		if (RE_rayobjectcontrol_test_break(&obj->rayobj.control)) {
			BLI_memarena_free(arena1);
			return;
		}

		if (root) {
			reorganize(root);
			remove_useless(root, &root);
			bvh_refit(root);
		
			pushup(root);
			pushdown(root);
			obj->root = root;
		}
		else
			obj->root = NULL;
	}
	else {
		/* TODO */
#if 0
		MemArena *arena2 = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, "vbvh arena2");
		BLI_memarena_use_malloc(arena2);
						   
		//Finds the optimal packing of this tree using a given cost model
		//TODO this uses quite a lot of memory, find ways to reduce memory usage during building
		OVBVHNode *root = BuildBinaryVBVH<OVBVHNode>(arena2).transform(obj->builder);
		VBVH_optimalPackSIMD<OVBVHNode, PackCost>(PackCost()).transform(root);
		obj->root = Reorganize_VBVH<OVBVHNode>(arena1).transform(root);
		
		BLI_memarena_free(arena2);
#endif
	}

	//Cleanup
	rtbuild_free(obj->builder);
	obj->builder = NULL;

	obj->node_arena = arena1;
	obj->cost = 1.0;
}

template<int StackSize>
static int intersect(VBVHTree *obj, Isect *isec)
{
	//TODO renable hint support
	if (RE_rayobject_isAligned(obj->root)) {
		if (isec->mode == RE_RAY_SHADOW)
			return bvh_node_stack_raycast<VBVHNode, StackSize, false, true>(obj->root, isec);
		else
			return bvh_node_stack_raycast<VBVHNode, StackSize, false, false>(obj->root, isec);
	}
	else
		return RE_rayobject_intersect( (RayObject *) obj->root, isec);
}

template<class Tree>
static void bvh_hint_bb(Tree *tree, LCTSHint *hint, float *UNUSED(min), float *UNUSED(max))
{
	//TODO renable hint support
	{
		hint->size = 0;
		hint->stack[hint->size++] = (RayObject *)tree->root;
	}
}

#if 0  /* UNUSED */
static void bfree(VBVHTree *tree)
{
	if (tot_pushup + tot_pushdown + tot_hints + tot_moves) {
		if (G.debug & G_DEBUG) {
			printf("tot pushups: %d\n", tot_pushup);
			printf("tot pushdowns: %d\n", tot_pushdown);
			printf("tot moves: %d\n", tot_moves);
			printf("tot hints created: %d\n", tot_hints);
		}

		tot_pushup = 0;
		tot_pushdown = 0;
		tot_hints = 0;
		tot_moves = 0;
	}
	bvh_free(tree);
}
#endif

/* the cast to pointer function is needed to workarround gcc bug: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11407 */
template<class Tree, int STACK_SIZE>
static RayObjectAPI make_api()
{
	static RayObjectAPI api = 
	{
		(RE_rayobject_raycast_callback) ((int   (*)(Tree *, Isect *)) & intersect<STACK_SIZE>),
		(RE_rayobject_add_callback)     ((void  (*)(Tree *, RayObject *)) & bvh_add<Tree>),
		(RE_rayobject_done_callback)    ((void  (*)(Tree *))       & bvh_done<Tree>),
		(RE_rayobject_free_callback)    ((void  (*)(Tree *))       & bvh_free<Tree>),
		(RE_rayobject_merge_bb_callback)((void  (*)(Tree *, float *, float *)) & bvh_bb<Tree>),
		(RE_rayobject_cost_callback)    ((float (*)(Tree *))      & bvh_cost<Tree>),
		(RE_rayobject_hint_bb_callback) ((void  (*)(Tree *, LCTSHint *, float *, float *)) & bvh_hint_bb<Tree>)
	};
	
	return api;
}

template<class Tree>
RayObjectAPI *bvh_get_api(int maxstacksize)
{
	static RayObjectAPI bvh_api256 = make_api<Tree, 1024>();
	
	if (maxstacksize <= 1024) return &bvh_api256;
	assert(maxstacksize <= 256);
	return 0;
}

RayObject *RE_rayobject_vbvh_create(int size)
{
	return bvh_create_tree<VBVHTree, DFS_STACK_SIZE>(size);
}
