private void raytrace(double energyEV, int numRays) {
    Grid2D grid = new Grid2D(600, 500);
    FloatProcessor imp;
    imp = new FloatProcessor(grid.getWidth(), grid.getHeight());
    imp.setPixels(grid.getBuffer());

    //		 SimpleVector startPosition = new SimpleVector(40,grid.getHeight()/2/scale, 0);
    SimpleVector startPosition = new SimpleVector(0, 0, 0);

    for (int i = 0; i < numRays; ++i) {
      followRay(startPosition.clone(), new SimpleVector(1, 0, 0), energyEV, imp, 0, 0);
    }
    imp.drawString(
        grid.getWidth() / scale + "cm",
        grid.getWidth() / 2 - 20,
        grid.getHeight() - 10,
        Color.WHITE);

    grid.show("Energy: " + energyEV + "eV, Material: " + material.getName());

    System.out.println(
        "Rejection sampling: average misses per draw: " + (float) sumMisses / (float) numDraws);

    numDraws = 0;
    sumMisses = 0;
  }