void blendLinGrad(PImage pg, Gradient gradient, float blend,
  int orx, int ory, int dex, int dey) {

  color clr;

  int w = pg.width;
  int h = pg.height;

  pg.loadPixels();
  for (int y = 0, x, i = 0; y < h; ++y) {
    for (x = 0; x < w; ++x, ++i) {
      clr = gradient.evaluate(
        project(orx, ory, dex, dey, x, y));
      pg.pixels[i] = lerpColor(pg.pixels[i], clr, blend);
    }
  }
  pg.updatePixels();
}