/**
 * this demo shows how to use a gestalt renderer, completly strip it of all
 * functionality and than render 'raw' opengl with just a single 'drawable'.
 * this is a proof of concept and not the ideal way to do it.<br/>
 * another reason for writing this demo was that processing 'messes' up some
 * opengl states, which are restored by 'gestalt'. this way one could say
 * that it is a bit saver to use opengl from within 'gestalt'.
 */

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

import gestalt.context.GLContext;
import gestalt.p5.GestaltPlugIn;
import gestalt.render.bin.RenderBin;
import gestalt.shape.AbstractDrawable;

import processing.opengl.*;


GestaltPlugIn gestalt;

void setup() {
  /* setup p5 */
  size(640, 480, OPENGL);

  /* create gestalt plugin */
  gestalt = new GestaltPlugIn(this);

  /* remove all gestalt presets */
  RenderBin myRenderBin = new RenderBin();
  gestalt.setBinRef(myRenderBin);
  myRenderBin.add(new RawOpenGL());
}


void draw() {
  background(0);
}


class RawOpenGL
extends AbstractDrawable {

  void draw(final GLContext theContext) {
    GL gl = gestalt.getGL();
    GLU glu = gestalt.getGLU();

    gl.glViewport(0, 0, width, height);
    gl.glMatrixMode(GL.GL_PROJECTION);
    gl.glLoadIdentity();
    glu.gluPerspective(45.0f,
    (float) width / (float) height,
    1.0,
    20.0);

    gl.glMatrixMode(GL.GL_MODELVIEW);
    gl.glLoadIdentity();

    gl.glTranslatef( -1.5f, 0.0f, -6.0f);
    gl.glBegin(GL.GL_TRIANGLES);
    gl.glColor3f(1.0f, 0.0f, 0.0f);
    gl.glVertex3f(0.0f, 1.0f, 0.0f);
    gl.glColor3f(0.0f, 1.0f, 0.0f);
    gl.glVertex3f( -1.0f, -1.0f, 0.0f);
    gl.glColor3f(0.0f, 0.0f, 1.0f);
    gl.glVertex3f(1.0f, -1.0f, 0.0f);
    gl.glEnd();

    gl.glTranslatef(3.0f, 0.0f, 0.0f);
    gl.glBegin(GL.GL_QUADS);
    gl.glColor3f(0.5f, 0.5f, 1.0f);
    gl.glVertex3f( -1.0f, 1.0f, 0.0f);
    gl.glVertex3f(1.0f, 1.0f, 0.0f);
    gl.glVertex3f(1.0f, -1.0f, 0.0f);
    gl.glVertex3f( -1.0f, -1.0f, 0.0f);
    gl.glEnd();
  }
}