#include "raster.h"

void Raster::touch(int index, Real value, Real x, Real y, Real dx, Real dy, TouchPointList &points) {

    dx = std::max(0.500001, dx);

    dy = std::max(0.500001, dy);

    int x0 = std::max(0, (int)ceil(x - dx));

    int y0 = std::max(0, (int)ceil(y - dy));

    int x1 = std::min(width, (int)ceil(x + dx));

    int y1 = std::min(height, (int)ceil(y + dy));

    dx = 1/dx;

    dy = 1/dy;

    for(int iy = y0; iy < y1; ++iy) {

        for(int ix = x0; ix < x1; ++ix) {

            Real ddx = (x-ix)*dx;

            Real ddy = (y-iy)*dy;

            if (ddx + ddy <= 1.00001) {

                Real &pixel = (*this)[iy][ix];

                if (pixel > value) {

                    points.push_back( TouchPoint(index, iy, ix, pixel, value) );

                    pixel = value;

                }

            }

        }

    }

}