source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/BvhExporter.cpp @ 3273

#include "BvhExporter.h"

using namespace std;

// MAGIC of all bin exports
#ifndef MAGIC 
#define MAGIC 0x827923
#endif

#define BVH_VERSION 2.1

namespace CHCDemoEngine
{

static int currentIdx = 0;


void BvhExporter::SaveNode(BvhNode *node, FILE *fw) 
{
        if (!node) return;
        
        int buffer[4];

        if (node->IsLeaf()) 
        {
                BvhLeaf *leaf = (BvhLeaf*)node;
                
                buffer[0] = mTriangleRangeMap[leaf].first;
                buffer[1] = mTriangleRangeMap[leaf].second;
                buffer[2] = -1;//leaf->GetAxis();
                buffer[3] = currentIdx ++;

                fwrite(buffer, sizeof(int), 4, fw);
        }
        else
        {
                BvhInterior *interior = (BvhInterior *)node;
                
                buffer[0] = interior->mFirst;
                buffer[1] = interior->mLast;
                buffer[2] = 0;//interior->mAxis;
                buffer[3] = currentIdx ++;

                fwrite(buffer, sizeof(int), 4, fw);
                
                SaveNode(interior->GetFront(), fw);
                SaveNode(interior->GetBack(), fw);
        }
}


void BvhExporter::ConstructTriangleRangeMap(Bvh *bvh, 
                                                                                        BvhNode *node,
                                                                                        int &first, 
                                                                                        int &last)
{
        if (!node->IsLeaf())
        {
                int m;
                BvhInterior *interior = static_cast<BvhInterior *>(node);

                ConstructTriangleRangeMap(bvh, interior->GetFront(), first, m);
                int newFirst = m + 1;
                ConstructTriangleRangeMap(bvh, interior->GetBack(), newFirst, last);

                mTriangleRangeMap[node] = pair<int, int>(first, last);
        }
        else
        {
                //first = currentIdx;
                last = first + bvh->CountTriangles(node) - 1;
                //currentIdx = last;

                mTriangleRangeMap[node] = pair<int, int>(first, last);
        }
}


bool BvhExporter::Export(const string &filename, Bvh *bvh)
{
         cout << "Exporting bvh to file '" << filename.c_str() << "'" << endl;
  
         FILE *fw = fopen(filename.c_str(), "wb");

         if (fw == NULL) 
         {
                 cerr << "Error: Cannot open file for writing" << endl;
                 return false;
         }

         int buffer[6];
         buffer[0] = MAGIC;
         buffer[1] = BVH_VERSION * 1000;
         buffer[3] = 0; // construction method
         buffer[4] = 1; // termination leaves
         buffer[5] = bvh->CountNumNodes(bvh->GetStaticRoot());

         int first = 0, last;
         ConstructTriangleRangeMap(bvh, bvh->GetStaticRoot(), first, last);

         BvhNodeContainer nodes;
         bvh->CollectVirtualLeaves(bvh->GetStaticRoot(), nodes);

         vector<int> triangles;

         BvhNodeContainer::const_iterator it, it_end = nodes.end();

         for (it = nodes.begin(); it != it_end; ++ it)
         {
                 BvhNode *node = *it;

                 int f = mTriangleRangeMap[node].first;
                 int l = mTriangleRangeMap[node].second;

                 for (int i = f; i <= l; ++ i)
                 {
                         triangles.push_back(i);
                 }
         }

         buffer[2] = (int)triangles.size();
         fwrite(buffer, sizeof(int), 6, fw);

         cout << "writing " << (int)triangles.size() << " triangle ids ..." << endl;

         // export sorted triangle IDs
         for (size_t i = 0; i < triangles.size(); ++ i) 
         {
                 fwrite(&triangles[i], sizeof(int), 1, fw);
         }

         cout << "writing bvh nodes ..." << endl;
         
         SaveNode(bvh->GetStaticRoot(), fw);
         
         cout << "successfully exported bvh" << endl;
         fclose(fw);

         return true;
}


}