Color blending with OpenGL

/**
blending taken from http://wiki.processing.org/index.php?title=Color_Blending_with_OpenGL
@author mflux
*/
 
import processing.opengl.*;
import javax.media.opengl.GL;   //  <-- don't forget to include this!
 
//  an access point to opengl
GL gl;	
 
void setup(){
  size(800,160,OPENGL);  
 
  //  hook into opengl
  gl=((PGraphicsOpenGL)g).gl;	    
 
}
 
void draw(){ 
  background(0);
  fill(20);  
  stroke(50);
 
  float x = 0;    
  translate(0,5);   
 
  //  normal
  gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
  gl.glBlendEquation(GL.GL_FUNC_ADD);	    	  
  for(int i=0;i<200; i++){
    x = lerp(x, width, 0.05f);
    ellipse(x,40, 60, 60);
  }
 
  x = 0;
  translate(0,70);
 
  //  additive blending
  gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE);    
  for(int i=0;i<200; i++){
    x = lerp(x, width, 0.05f);
    ellipse(x,40, 60, 60);
  }  
}