code: public void setColor(int corner, float r, float g, float b, float a) {
  		if (corners == null) {
  			corners = new Color[] {new Color(1,1,1,1f),new Color(1,1,1,1f), new Color(1,1,1,1f), new Color(1,1,1,1f)};
  		}
  		
  		corners[corner].r = r;
  		corners[corner].g = g;
  		corners[corner].b = b;
  		corners[corner].a = a;
  	}
docs: Set the color of the given corner when this image is rendered. This is
  useful lots of visual effect but especially light maps
  
  @param corner The corner identifier for the corner to be set
  @param r The red component value to set (between 0 and 1)
  @param g The green component value to set (between 0 and 1)
  @param b The blue component value to set (between 0 and 1)
  @param a The alpha component value to set (between 0 and 1)