source: GTP/trunk/Lib/Vis/Preprocessing/src/DifferenceSampling.cpp @ 2548

#include "SamplingStrategy.h"
#include "Intersectable.h"
#include "DifferenceSampling.h"
#include "ViewCell.h"
#include "ViewCellsManager.h"
#include "Preprocessor.h"


#ifdef GTP_INTERNAL
#include "ArchModeler2MLRT.hxx"
#endif


namespace GtpVisibilityPreprocessor {


/** Collects the pvs of the objects which are 
        in the first but not in the second pvs.
*/
static void GetPvsDifference(const ObjectPvs &largerPvs, 
                                                         const ObjectPvs &smallerPvs, 
                                                         ObjectContainer &pvsDifference)
{
        Intersectable::NewMail();
        Intersectable *obj;

        ObjectPvsIterator bit = smallerPvs.GetIterator();

        // mail smaller pvs
        while (bit.HasMoreEntries())
        {
                obj = bit.Next();
                obj->Mail();
        }

        ObjectPvsIterator ait = largerPvs.GetIterator();

        // write differece pvs
        while (ait.HasMoreEntries())
        {
                obj = ait.Next();
                pvsDifference.push_back(obj);

                //if (!obj->Mailed())
                //      c.AddSampleDirty(obj, 0);
        }
}


DifferenceSampling::DifferenceSampling(Preprocessor &preprocessor):
SamplingStrategy(preprocessor), mCurrentViewCell(0), mNumSamples(0)
{}


void DifferenceSampling::ComputeDifferenceSet(ViewCell *vc, 
                                                                                          ObjectContainer &differenceSet)
{
        const ObjectPvs &pvs = vc->GetPvs();
        const float filterSize = 100;
        ObjectPvs filteredPvs;

    PvsFilterStatistics pvsStats = mPreprocessor.
                mViewCellsManager->ApplyFilter2(vc, 
                                                false, 
                                                                                filterSize, 
                                                                                filteredPvs);

        //mDifferencePvs.Clear(false);
        //mDifferencePvs.Reserve(filteredPvs.GetSize());
        mPvsDifference.clear();
        mPvsDifference.reserve(filteredPvs.GetSize());

        GetPvsDifference(filteredPvs, pvs, mPvsDifference);
}


bool DifferenceSampling::GenerateSample(SimpleRay &ray)
{
        if (mNumSamples -- <= 0)
        {
                ViewCellContainer &viewCells = mPreprocessor.mViewCellsManager->GetViewCells();
                const int vcIdx = (int)RandomValue(0, (float)viewCells.size() - 0.5f);

                mCurrentViewCell = viewCells[vcIdx];

                ComputeDifferenceSet(mCurrentViewCell, mPvsDifference);

                // n samples per object
                const int n = 50;
                mNumSamples = mPvsDifference.size() * n;
        }

        Vector3 origin, direction; 
        Vector3 point;
        Vector3 normal, vcnormal;

        // get a new object from the difference set
        const int objIdx = (int)RandomValue(0, (float)mPvsDifference.size() - 0.5f);
    Intersectable *object = mPvsDifference[objIdx];

        // cast a ray from the view cells border towards the object
        object->GetRandomSurfacePoint(point, normal);
        mCurrentViewCell->GetRandomEdgePoint(origin, vcnormal);

        direction = point - origin;

        // $$ jb the pdf is yet not correct for all sampling methods!
        const float c = Magnitude(direction);

        if ((c <= Limits::Small) /*|| (DotProd(direction, normal) < 0)*/)
        {
                return false;
        }

        // $$ jb the pdf is yet not correct for all sampling methods!
        const float pdf = 1.0f;
        //cout << "p: " << point << " ";
        direction *= 1.0f / c;
        ray = SimpleRay(origin, direction, DIFFERENCE_SAMPLING_BASED_DISTRIBUTION, pdf);

        //cout << "ray: " << ray.mOrigin << " " << ray.mDirection << endl;

        return true;
}


}