src/RotatedGridSampleGenerator.h

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#ifndef ROTATEDGRIDSAMPLEGENERATOR_H
#define ROTATEDGRIDSAMPLEGENERATOR_H

#include "RegularSampleGenerator.h"
#include <cmath>

class RotatedGridSampleGenerator : public RegularSampleGenerator
{
public:
    RotatedGridSampleGenerator(float angle = 45.0f)
        :   RegularSampleGenerator(),
            mSin(sinf(angle*M_PI/180.0)),
            mCos(cosf(angle*M_PI/180.0))
    {
    }

    void samples(int n, float u[], float v[], float weight[]) const
    {
        // get samples on a regular grid
        RegularSampleGenerator::samples(n, u, v, weight);

        for (int i=0; i < n; i++)
        {
            // move pixel center to (0, 0)
            u[i] -= 0.5f;
            v[i] -= 0.5f;

            // rotate by angle
            float tmpU = u[i];
            u[i] = u[i]*mCos - v[i]*mSin;
            v[i] = tmpU*mSin + v[i]*mCos;

            // move back
            u[i] += 0.5f;
            v[i] += 0.5f;
        }
    }

private:
    float mSin;
    float mCos;
};

#endif

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