source: GTP/trunk/Lib/Vis/Preprocessing/src/ObjectPvs.cpp @ 2606

#include <iostream>
#include <stack>

#include "Mesh.h"
#include "ObjectPvs.h"
#include "Intersectable.h"
#include "IntersectableWrapper.h"
#include "KdTree.h"
#include "common.h"
#include "BvHierarchy.h"

using namespace std;

namespace GtpVisibilityPreprocessor {


/** the pvs is the number of different objects in the node leaves
        We eliminate already accounted kd nodes and objects using mailboxing. 
*/
static int EvalKdNodeContribution(KdIntersectable *kdobj)
{
        int pvs = 0;
        stack<KdNode *> tStack;

        tStack.push(kdobj->GetItem());

        while (!tStack.empty())
        {
                KdNode *node = tStack.top();
                tStack.pop();

                // already processed node (=> objects already in pvs)?
                if (!node->Mailed())
                {
                        node->Mail();

                        if (node->IsLeaf())
                        {
                                KdLeaf *leaf = static_cast<KdLeaf *>(node);
                       
                                // add #objects exclusivly in this node
                                pvs += (int)(leaf->mObjects.size() - leaf->mMultipleObjects.size());

                                // Objects already accounted for can only be found among those
                                // which are referenced in more than one leaf
                                ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();
                                                
                                for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
                                {
                                        Intersectable *object = *oit;                                           
                            
                                        if (!object->Mailed())
                                        {
                                                object->Mail();
                                                ++ pvs;
                                        }
                                }
                        }
                        else // traverse tree
                        {
                                KdInterior *interior = static_cast<KdInterior *>(node);

                                tStack.push(interior->mFront);
                                tStack.push(interior->mBack);
                        }
                }
        }

        return pvs;
}


/** Returns the the number of new (unmailed) objects in the leaves of the node.
        We eliminate already accounted bvh nodes and objects using mailboxing. 
*/
static float EvalBvhNodeContribution(BvhNode *bvhObj)
{
        BvhNode *node;

        // hack for choosing which node to account for
        if (bvhObj->IsLeaf())
                node = static_cast<BvhLeaf *>(bvhObj)->GetActiveNode();
        else
                node = bvhObj;

        // early exit
        if (node->IsLeaf())     
        {       
                BvhLeaf *leaf = static_cast<BvhLeaf *>(node);
                // objects already accounted for
                if (leaf->Mailed())
                        return 0;

                leaf->Mail();
                return (float)leaf->mObjects.size();
        }                        

        // compute leaf pvs
        float pvs = 0;
        stack<BvhNode *> tStack;
        tStack.push(node);

        while (!tStack.empty())
        {
                node = tStack.top();
                tStack.pop();

                // already processed node (=> objects already in pvs)?
                if (!node->Mailed())
                {
                        node->Mail();

                        if (node->IsLeaf())
                        {
                                BvhLeaf *leaf = static_cast<BvhLeaf *>(node);

                                // add #objects exclusivly in this node
                                pvs += (float)leaf->mObjects.size();
                        }
                        else // traverse tree
                        {
                                BvhInterior *interior = static_cast<BvhInterior *>(node);

                                tStack.push(interior->GetFront());
                                tStack.push(interior->GetBack());
                        }
                }
        }

        return pvs;
}


float ObjectPvs::EvalPvsCost() const
{
        float pvs = 0;

        Intersectable::NewMail();
        KdNode::NewMail();

        ObjectPvsIterator pit = GetIterator();

        while (pit.HasMoreEntries())
        {               
                Intersectable *obj = pit.Next();

                switch (obj->Type())
                {
                        case Intersectable::KD_INTERSECTABLE:
                                {
                                        // found kd node
                                        KdIntersectable *kdObj = static_cast<KdIntersectable *>(obj);
                                        pvs += EvalKdNodeContribution(kdObj);   
                                        break;
                                }
                        case Intersectable::BVH_INTERSECTABLE:
                                {
                                        BvhNode *bvhObj = static_cast<BvhNode *>(obj);
                                        pvs += EvalBvhNodeContribution(bvhObj);
                                        break;
                                }
                        default:
                                // hack: should use assigned cost here
                                ++ pvs;
                                
                                break;
                }
        }

        return pvs;
}

}