class MorphSurface extends PImage {
  
  private PImage img1, img2;
  private float[][] mix;
  private float FADE_STRENGTH = 0.99;
  
  
  
  MorphSurface(PImage _img1, PImage _img2) {
    
    super(_img1.width,_img1.height);
    
    img1 = _img1;
    img2 = _img2;
    
    for (int x=0;x<width;x++) for (int y=0;y<height;y++) this.set(x,y,img2.get(x,y));
    
    mix = new float[this.width][this.height];
    for (int x=0;x<width;x++) for (int y=0;y<height;y++) mix[x][y] = 0.0;
  }
  
  
  
  public void morphAt(int x, int y, float p) {
    if (x>=0&&x<width&&y>=0&&y<height) {
      mix[x][y] += p;
      if (mix[x][y]>1.0) mix[x][y]=1.0;
    }
  }
  
  
  public void update() {
    for (int x=0;x<width;x++) for (int y=0;y<height;y++) {
      mix[x][y] *= FADE_STRENGTH;
      set(x,y,mixColor(img2.get(x,y),img1.get(x,y),mix[x][y]));
    }
  }
  
}