src/Texture2D.h

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#ifndef TEXTURE2D_HXX
#define TEXTURE2D_HXX


#include <string>

#include "Texture.h"
#include "PNGImage.h"


class Texture2D : public Texture
{
public:
    Texture2D(int resX, int resY)
        : Texture(),
            mResX(resX),
            mResY(resY)
    {
        mImage = new PNGImage(resX, resY);
    }

    Texture2D(const std::string & filename)
        : Texture(),
            mResX(1),
            mResY(1)
    {
        mImage = new PNGImage(1, 1);
        if (!mImage->read(filename))
        {
            delete mImage;
            assert(false);
        }
        mResX = mImage->width();
        mResY = mImage->height();
    }

    ~Texture2D()
    {
        delete mImage;
    }

    RGBAColor texel(float u, float v) const
    {
        const float x = u * mResX - 0.5f;
        const float y = v * mResY - 0.5f;
        switch (interpolationMode())
        {
            case NEAREST:
                return wrappedTexel(static_cast<int>(roundf(x)), static_cast<int>(roundf(y)));
            case LINEAR:
            {
                const int ix = static_cast<int>(floorf(x));
                const int iy = static_cast<int>(floorf(y));

                // neighbourhood
                const RGBAColor t00 = wrappedTexel(ix,   iy);
                const RGBAColor t10 = wrappedTexel(ix+1, iy);
                const RGBAColor t01 = wrappedTexel(ix,   iy+1);
                const RGBAColor t11 = wrappedTexel(ix+1, iy+1);

                // interpolate
                const RGBAColor tx0 = t00 + (x-ix)*(t10-t00);
                const RGBAColor tx1 = t01 + (x-ix)*(t11-t01);
                return tx0 + (y-iy)*(tx1-tx0);
            }
        }
        return RGBAColor();
    }

    int resX() const
    {
        return mResX;
    }

    int resY() const
    {
        return mResY;
    }

private:
    Image * mImage;

    int     mResX;
    int     mResY;


    RGBAColor wrappedTexel(int x, int y) const
    {
        // wrap texture coordinates
        switch (wrapMode())
        {
            case WRAP:
                if (x < 0)
                    x = 0;
                if (y < 0)
                    y = 0;
                if (x >= mResX)
                    x = mResX-1;
                if (y >= mResY)
                    y = mResY-1;
            case REPEAT:
                x %= mResX;
                y %= mResY;
                if (x < 0)
                    x += mResX;
                if (y < 0)
                    y += mResY;
        }
        return RGBAColor(mImage->pixel(x, y));
    }
};

#endif

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