import java.nio.FloatBuffer;
import java.nio.IntBuffer;

import javax.media.opengl.GL;
import javax.media.opengl.glu.GLU;

import com.sun.opengl.util.BufferUtil;

import processing.core.PApplet;
import processing.opengl.*;

PGraphicsOpenGL pgl;
GL gl;
GLU glu;

float aspect, camZ;

// Must be arrays of size 1 for glGenBuffers
int[] vindex_vbo = new int[1];
int[] vertices_vbo = new int[1];
int[] colors_vbo = new int[1];

boolean dataInited = false;

void setup(){
  size(400,400,OPENGL);
  // aspect and camZ are integral to both p5 and GL camera settings
  aspect=(float)width/(float)height;  
  // (but p5 includes them automatically, see "camera()"
  camZ= (float) (2.0f * ((height/2.0f) / Math.tan(PI*60.0f/360.0f))); 

}


void draw(){
  pgl = (PGraphicsOpenGL) g;
  gl = pgl.beginGL();
  glu = pgl.glu;

  gl.glClearColor(0,0,0,0);
  gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
  gl.glShadeModel(GL.GL_SMOOTH);

  // tell GL that the camera is being set up now:
  gl.glMatrixMode(GL.GL_PROJECTION);  
  gl.glLoadIdentity();

  // Equivalent to P5 perspective() 
  glu.gluPerspective(60.0, aspect, camZ/10.0, camZ*10.0); 
  // Equivalent to P5 camera()
  glu.gluLookAt(0, 0, 200, 0, 0, 0, 0, 1, 0);

  // tell GL the following rotations will be applied to models, not the camera
  gl.glMatrixMode(GL.GL_MODELVIEW); 
  gl.glLoadIdentity();

//  gl.glEnable(GL.GL_BLEND);
  if(dataInited == false)
    initData(gl);
  else
    drawBox(gl);

  pgl.endGL();
}

public void initData(GL gl){
  FloatBuffer pos  = BufferUtil.newFloatBuffer( 24 );
  float[] verts = new float[] {   
    -1, -1,  1,
    1, -1,  1,
    1,  1,  1,
    -1,  1,  1,
    -1, -1, -1,
    1, -1, -1,
    1,  1, -1,
    -1,  1, -1       };

  for(int i = 0; i < verts.length; i++){
    verts[i] *= 10.0f;
    pos.put(verts[i]);
  }
  gl.glGenBuffers( 1, vertices_vbo, 0 );
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, vertices_vbo[0] );
  gl.glBufferData( GL.GL_ARRAY_BUFFER, 8 * 3 * BufferUtil.SIZEOF_FLOAT, pos, GL.GL_STATIC_DRAW );
  pos = null;
  verts = null;


  FloatBuffer cols = BufferUtil.newFloatBuffer( 72 );
  for(int i = 0; i < 24; i++){
    cols.put(random(1.0f));
    cols.put(random(1.0f));
    cols.put(1.0f);
  }
  gl.glGenBuffers( 1, colors_vbo, 0 );
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, colors_vbo[0] );
  gl.glBufferData( GL.GL_ARRAY_BUFFER, 24 * 3 * BufferUtil.SIZEOF_FLOAT, cols, GL.GL_STATIC_DRAW );
  cols = null;

  IntBuffer faces  = BufferUtil.newIntBuffer( 24 );
  int[] facePts = new int[] {	
    0,3,2,1,
    5,6,7,4,
    4,7,3,0,
    1,2,6,5,
    4,0,1,5,
    3,7,6,2       };
  faces.put(facePts);
  gl.glGenBuffers( 1, vindex_vbo, 0 );
  gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, vindex_vbo[0] );
  gl.glBufferData( GL.GL_ELEMENT_ARRAY_BUFFER, 24 * BufferUtil.SIZEOF_INT, faces, GL.GL_STATIC_DRAW );
  faces = null;
  facePts = null;		

  dataInited = true;
}

public void drawBox(GL gl){
  gl.glEnableClientState(GL.GL_COLOR_ARRAY);
  gl.glEnableClientState(GL.GL_VERTEX_ARRAY);

  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, colors_vbo[0] );
  gl.glColorPointer(3,GL.GL_FLOAT,0,0);

  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, vertices_vbo[0] );
  gl.glVertexPointer(3,GL.GL_FLOAT,0,0);

  gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, vindex_vbo[0] );
  gl.glDrawElements( GL.GL_QUADS, 24, GL.GL_UNSIGNED_INT, 0 ); 

  gl.glDisableClientState(GL.GL_VERTEX_ARRAY);
  gl.glDisableClientState(GL.GL_COLOR_ARRAY);
}

public void finalize(){
  System.out.println("Bye bye");
  gl.glDeleteBuffers( 1, vertices_vbo, 0 );
  gl.glDeleteBuffers( 1, colors_vbo, 0 );
  gl.glDeleteBuffers( 1, vindex_vbo, 0 );
}