パーリンノイズの風景

/**
* landscape of perlin noise
*
* @author aa_debdeb
* @date 2016/08/02
*/

void setup(){
  size(500, 500);
  noFill();
  mousePressed();
}

void draw(){}

void mousePressed(){
  float noiseX = random(10000);
  float noiseY = random(10000);
  float[][] values = new float[width][height];
  for(int x = 0; x < width; x++){
    for(int y = height - 1; y >= 0; y--){
      if(x == 0 && y == height - 1){
        values[x][y] = random(150, 200);
      } else if(y == height - 1){
        float vleft = values[x - 1][y];
        float v = vleft;
        v += map(noise(x * 0.1 + noiseX, y * 0.1 + noiseY), 0, 1, -10, 10);
        v = constrain(v, 50, 255);
        values[x][y] = v;
        if(v < vleft){
          stroke(v - map(vleft - v, 0, 10, 0, 50));
        } else {
          stroke(v);
        }
      } else if(x == 0){
        float vdown = values[x][y + 1];
        float v = vdown;
        v += map(noise(x * 0.1 + noiseX, y * 0.1 + noiseY), 0, 1, -10, 10);        
        v = constrain(v, 50, 255);
        values[x][y] = v;
        if(v < vdown){
          stroke(v - map(vdown - v, 0, 10, 0, 50));
        } else {
          stroke(v);
        }
      } else {
        float vleft = values[x - 1][y];
        float vdown = values[x][y + 1];
        float v = (vleft + vdown) / 2.0;
        v += map(noise(x * 0.1 + noiseX, y * 0.1 + noiseY), 0, 1, -10, 10);
        v = constrain(v, 50, 255);
        values[x][y] = v;
        if(v < vleft ||  v < vdown){
          if(vleft < vdown){
            stroke(v - map(vdown - v, 0, 10, 0, 50));
          } else {
            stroke(v - map(vleft - v, 0, 10, 0, 50));          
          }
        } else {
          stroke(v);
        }
      }
      point(x, y);
    }
  }
}