Vertex Buffer Object (VBO)

import processing.opengl.*;
import javax.media.opengl.GL;
import com.sun.opengl.util.BufferUtil;
import java.nio.FloatBuffer;
 
PGraphicsOpenGL pgl;
GL gl;
int quadlength;
int[] quad_vbo = new int[1];
 
void setup() {
 size(300,300,OPENGL);
 pgl = (PGraphicsOpenGL) g;
 gl = pgl.gl;
 initVBO();
}
void draw() {
 pgl.beginGL();
 gl.glEnableClientState(GL.GL_VERTEX_ARRAY);
 gl.glBindBuffer( GL.GL_ARRAY_BUFFER, quad_vbo[0]);
 gl.glVertexPointer(2,GL.GL_FLOAT,0,0);
 gl.glDrawArrays( GL.GL_QUADS, 0, quadlength);
 gl.glBindBuffer( GL.GL_ARRAY_BUFFER, 0);
 gl.glDisableClientState(GL.GL_VERTEX_ARRAY);
 pgl.endGL();
}
 
void initVBO() {
 Vector quadvbo = new Vector();
 quadvbo.addElement( new ms_vector2(20,20));
 quadvbo.addElement( new ms_vector2(200,20));
 quadvbo.addElement( new ms_vector2(200,200));
 quadvbo.addElement( new ms_vector2(20,200));
 
 quadlength = quadvbo.size();
 if (quadlength > 0) {
   pgl.beginGL();
   gl.glGenBuffers( 1, quad_vbo, 0 );
   gl.glBindBuffer( GL.GL_ARRAY_BUFFER, quad_vbo[0] );
   gl.glBufferData( GL.GL_ARRAY_BUFFER, quadlength * 2 * BufferUtil.SIZEOF_FLOAT, ms_vector2_to_float_buffer( quadvbo ), GL.GL_STATIC_DRAW );
   gl.glBindBuffer( GL.GL_ARRAY_BUFFER, 0);
   pgl.endGL();
   quadvbo = null;
 }
}
 
class ms_vector2
{
 float x, y;
 
 // constructor
 ms_vector2()
 {
   this.x = 0;
   this.y = 0;
 }
 
 ms_vector2( float _x, float _y)
 {
   this.x = _x;
   this.y = _y;
 }
}
 
// buffer converters
FloatBuffer ms_vector2_to_float_buffer( Vector _vector )
{
 FloatBuffer a  = BufferUtil.newFloatBuffer( _vector.size() * 2 );      
 
 for( int i = 0; i < _vector.size(); i++ )
 {
   ms_vector2 v = (ms_vector2) _vector.elementAt( i );
   a.put( v.x );
   a.put( v.y );
 }
 a.rewind();
 return a;
}