任意の２つの色でグラデーション

/**
* Two Color Gradation
*
* @autor aa_debdeb
* @date 2015/09/09
*/

// color1
float r1 = 255.0;
float g1 = 20.0;
float b1 = 147.0;
// color2
float r2 = 255.0;
float g2 = 215.0;
float b2 = 0.0;

void setup(){
  size(500, 500); 
  
  loadPixels();
  float rStep = (r1 - r2) / (width + height);
  float gStep = (g1 - g2) / (width + height);
  float bStep = (b1 - b2) / (width + height);
  for(int h = 0; h < height; h++){
    for(int w = 0; w < width; w++){
      float r = r1 - (w + h) * rStep;
      float g = g1 - (w + h) * gStep;
      float b = b1 - (w + h) * bStep;
      pixels[h * width + w] = color(r, g, b);
    }
  }
  updatePixels();

}