src/rcrt/textures/ImageTexture.cpp

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#include "ImageTexture.h"

namespace rcrt
{

ImageTexture::ImageTexture(Image* img) : image(img)
{
}

ImageTexture::~ImageTexture()
{
        delete image;
}

RGBAColor ImageTexture::getColor(const Point2D& p) const
{
        float u = p.x();
        float v = p.y();
        float resX = image->getWidth();
        float resY = image->getHeight();
        // compute texel coordinates
        // we add 0.5, since the texel is sampled in the middle of the pixel (see OpenGL linear interpolation)
        float px = resX * u + 0.5;
        float py = resY * v + 0.5;
        
//      // find sampling positions of neighbour texels
    Point2D uv[2][2];
    uv[0][0] = Point2D(floor(px - 1), floor(py - 1));
    uv[0][1] = Point2D(floor(px - 1), floor(py));
    uv[1][0] = Point2D(floor(px), floor(py - 1));
    uv[1][1] = Point2D(floor(px), floor(py));

//      // get the four neighbours
//      // make use of _GetTexel method to ensure also handling of proper wrap modes
    //RGBAColor tex[2][2];
    const RGBAColor& tex00 = image->getPixel((int)uv[0][0].x(), (int)uv[0][0].y());
    const RGBAColor& tex01 = image->getPixel((int)uv[0][1].x(), (int)uv[0][1].y());
    const RGBAColor& tex10 = image->getPixel((int)uv[1][0].x(), (int)uv[1][0].y());
    const RGBAColor& tex11 = image->getPixel((int)uv[1][1].x(), (int)uv[1][1].y());

    // get fractional parts of the texel coordinates
    // based on the fractional part we interpolate the values
    double ix, iy;
    float fx = modf(px, &ix);
    float fy = modf(py, &iy);

    // interpolate texels bilinearly
    RGBAColor result = tex00*(1-fx)*(1-fy) + tex10*fx*(1-fy) + tex01*(1-fx)*fy + tex11*fx*fy;

    // return new value
    return result;
}

Vec3D ImageTexture::getBump(const Point2D& p, const float& scale,const Matrix4D& onb) const
{
        float dx = 1.0f / (image->getWidth() - 1);
    float dy = 1.0f / (image->getHeight() - 1);
    float b0 = getColor(p).getLuminance();
    float bx = image->getPixel(p.x() + dx, p.y()).getLuminance();
    float by = image->getPixel(p.x(), p.y() + dy).getLuminance();
    
//    w.normalize(onb.w);
//    if ((Math.abs(onb.w.x) < Math.abs(onb.w.y)) && (Math.abs(onb.w.x) < Math.abs(onb.w.z))) {
//        onb.v.x = 0;
//        onb.v.y = onb.w.z;
//        onb.v.z = -onb.w.y;
//    } else if (Math.abs(onb.w.y) < Math.abs(onb.w.z)) {
//        onb.v.x = onb.w.z;
//        onb.v.y = 0;
//        onb.v.z = -onb.w.x;
//    } else {
//        onb.v.x = onb.w.y;
//        onb.v.y = -onb.w.x;
//        onb.v.z = 0;
//    }
//    Vector3.cross(onb.v.normalize(), onb.w, onb.u);
    
    //return onb * Vec3D(0,0,1);
    
    //return Vec3D(0,1,0);
    
    //return onb * (Vec3D(1,1,1) * b0);
    
        return (onb * Vec3D(scale * (bx - b0) / dx, scale * (by - b0) / dy, 1)).normalize();
}

}

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