Method get_color

examples/pde/bhrt.cpp:857–882

    Background(const af::array& image_) { image = image_; }

    af::array get_color(const af::array& ray_dir) const {
        auto spherical_dir = cart_to_sph_position(ray_dir);

        auto img_height = image.dims()[0];
        auto img_width  = image.dims()[1];
        auto count      = ray_dir.dims()[1];

        // Spherical mapping of the direction to a pixel of the image
        af::array o = spherical_dir(1, af::span);
        af::array p = spherical_dir(2, af::span);

        auto x = (p / af::Pi + 1.0) * img_width / 2.0;
        auto y = (o / af::Pi) * img_height;

        // Interpolate the colors of the image from the calculated pixel
        // positions
        af::array colors = af::approx2(image, af::moddims(y.as(f32), count),
                                       af::moddims(x.as(f32), count),
                                       af::interpType::AF_INTERP_CUBIC_SPLINE);

        // Zero out the color of any null rays
        colors = af::moddims(colors, af::dim4(count, 3));
        af::replace(colors, !af::isNaN(colors), 0.f);

        return colors;
    }
};

/**