code: public void adjustColor(float r, float g, float b, float a) {
  		if (color == Color.white) {
  			color = new Color(1,1,1,1f);
  		} 
  		color.r += r;
  		color.g += g;
  		color.b += b;
  		color.a += a;
  	}
docs: Adjust (add) the color of the particle
  
  @param r
  The amount to adjust the red component by
  @param g
  The amount to adjust the green component by
  @param b
  The amount to adjust the blue component by
  @param a
  The amount to adjust the alpha component by