vbvh.h

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/*
 * ***** 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 *****
 */

#include <assert.h>
#include <algorithm>

#include "BLI_memarena.h"

#include "rayobject_rtbuild.h"

/*
 * VBVHNode represents a BVHNode with support for a variable number of childrens
 */
struct VBVHNode
{
    float   bb[6];

    VBVHNode *child;
    VBVHNode *sibling;
};


/*
 * Push nodes (used on dfs)
 */
template<class Node>
inline static void bvh_node_push_childs(Node *node, Isect *UNUSED(isec), Node **stack, int &stack_pos)
{
    Node *child = node->child;

    if(is_leaf(child))
    {
        stack[stack_pos++] = child;
    }
    else
    {
        while(child)
        {
            //Skips BB tests on primitives
/*
            if(is_leaf(child->child))
                stack[stack_pos++] = child->child;
            else
*/
                stack[stack_pos++] = child;
                
            child = child->sibling;
        }
    }
}


template<class Node>
int count_childs(Node *parent)
{
    int n = 0;
    for(Node *i = parent->child; i; i = i->sibling)
    {
        n++;
        if(is_leaf(i))
            break;
    }
        
    return n;
}


template<class Node>
void append_sibling(Node *node, Node *sibling)
{
    while(node->sibling)
        node = node->sibling;
        
    node->sibling = sibling;
}


/*
 * Builds a binary VBVH from a rtbuild
 */
template<class Node>
struct BuildBinaryVBVH
{
    MemArena *arena;
    RayObjectControl *control;

    void test_break()
    {
        if(RE_rayobjectcontrol_test_break(control))
            throw "Stop";
    }

    BuildBinaryVBVH(MemArena *a, RayObjectControl *c)
    {
        arena = a;
        control = c;
    }

    Node *create_node()
    {
        Node *node = (Node*)BLI_memarena_alloc( arena, sizeof(Node) );
        assert( RE_rayobject_isAligned(node) );

        node->sibling = NULL;
        node->child   = NULL;

        return node;
    }
    
    int rtbuild_split(RTBuilder *builder)
    {
        return ::rtbuild_heuristic_object_split(builder, 2);
    }
    
    Node *transform(RTBuilder *builder)
    {
        try
        {
            return _transform(builder);
            
        } catch(...)
        {
        }
        return NULL;
    }
    
    Node *_transform(RTBuilder *builder)
    {
        int size = rtbuild_size(builder);

        if(size == 0) {
            return NULL;
        }
        else if(size == 1)
        {
            Node *node = create_node();
            INIT_MINMAX(node->bb, node->bb+3);
            rtbuild_merge_bb(builder, node->bb, node->bb+3);        
            node->child = (Node*) rtbuild_get_primitive( builder, 0 );
            return node;
        }
        else
        {
            test_break();
            
            Node *node = create_node();

            Node **child = &node->child;

            int nc = rtbuild_split(builder);
            INIT_MINMAX(node->bb, node->bb+3);

            assert(nc == 2);
            for(int i=0; i<nc; i++)
            {
                RTBuilder tmp;
                rtbuild_get_child(builder, i, &tmp);
                
                *child = _transform(&tmp);
                DO_MIN((*child)->bb, node->bb);
                DO_MAX((*child)->bb+3, node->bb+3);
                child = &((*child)->sibling);
            }

            *child = 0;
            return node;
        }
    }
};

/*
template<class Tree,class OldNode>
struct Reorganize_VBVH
{
    Tree *tree;
    
    Reorganize_VBVH(Tree *t)
    {
        tree = t;
    }
    
    VBVHNode *create_node()
    {
        VBVHNode *node = (VBVHNode*)BLI_memarena_alloc(tree->node_arena, sizeof(VBVHNode));
        return node;
    }
    
    void copy_bb(VBVHNode *node, OldNode *old)
    {
        std::copy( old->bb, old->bb+6, node->bb );
    }
    
    VBVHNode *transform(OldNode *old)
    {
        if(is_leaf(old))
            return (VBVHNode*)old;

        VBVHNode *node = create_node();
        VBVHNode **child_ptr = &node->child;
        node->sibling = 0;

        copy_bb(node,old);

        for(OldNode *o_child = old->child; o_child; o_child = o_child->sibling)
        {
            VBVHNode *n_child = transform(o_child);
            *child_ptr = n_child;
            if(is_leaf(n_child)) return node;
            child_ptr = &n_child->sibling;
        }
        *child_ptr = 0;
        
        return node;
    }   
};
*/