// ------------------------------------------------------------------
//   This code was written by Philipp Seifried, except where
//   otherwise stated.
//   You're permitted to do whatever you want with the parts
//   I wrote, including modification, distribution and 
//   removal of this notice, as long as I will not be held
//   responsible for any harm that results in the use of
//   this code.
//   Remember that for this to work, you will also need the
//   JOGL classes to be found at
//   https://jogl.dev.java.net/
//   For instructions, refer to
//   http://www.repeatwhiletrue.com/p5/P5JOGL.html

//   Have fun!
// ------------------------------------------------------------------

Frame oglFrame; // our openGL Window
GLCanvas canvas; // the component openGL will render to
JOGLRenderer renderer; // our custom event listener that will do the rendering

float ourVariable; // We will use this one to do some fancy color warping.

void setup() {

  // ----------------- Add your own stuff here!
  size(320,240);
  ourVariable = 0;
  //    ...
  //    ...
  //    ...
  // ------------------------------------------

  // set up our window
  oglFrame = new Frame("Our very own OpenGL Window!");
  oglFrame.setSize( 800, 600 );

  renderer = new JOGLRenderer();

  // set the properties of our openGL component...
  GLCapabilities glCaps = new GLCapabilities();
  glCaps.setRedBits(8); // 32 bit color resolution
  glCaps.setBlueBits(8);
  glCaps.setGreenBits(8);
  glCaps.setAlphaBits(8);
  glCaps.setDoubleBuffered(true); // double buffered
  canvas = GLDrawableFactory.getFactory().createGLCanvas( glCaps );
  // add the renderer to the component and the component to our window.
  canvas.addGLEventListener(renderer);
  oglFrame.add( canvas );

  // let the program exit if our openGL window is shut down.
  oglFrame.addWindowListener(new WindowAdapter() {
    public void windowClosing(WindowEvent e) {
      System.exit(0);
    }
  });

  // show our openGL window!
  oglFrame.setVisible(true); 
  oglFrame.setFocusable(true);
  oglFrame.requestFocus();
}

void loop() {
  // ----------------- Add your own stuff here!
  ourVariable += 0.1;
  //    ...
  //    ...
  //    ...
  // ------------------------------------------
  canvas.display();
}


class JOGLRenderer implements GLEventListener
{

  public void init(GLDrawable drawable)
  {
    // fetch GL and GLU instances from our GLCanvas
    GL gl = drawable.getGL();
    GLU glu = drawable.getGLU();  
    
    // ----------------- Add your own stuff here!
    gl.glShadeModel(GL.GL_SMOOTH); // enable smooth shading
    gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // set the background color
    gl.glHint(GL.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_NICEST); // nice perspective correction
    gl.glEnable(GL.GL_DEPTH_TEST); // enable the z-Buffer
    gl.glDepthFunc(GL.GL_LEQUAL); // the z comparison function
    gl.glClearDepth(1.0f); // set the depth the z-Buffer will be cleared to
    gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT ); // clear the screen
    glu.gluPerspective(45.0f,(float)(800)/(float)(600),0.1f,100.0f); // and set up a perspective.
    // ------------------------------------------
    
  }

  public void display(GLDrawable drawable)
  {
    // -------- this is our render loop!
    GL gl = drawable.getGL(); // gl should be fetched like this in every frame...
    
    // ----------------- Add your own stuff here!
    float a = sin(ourVariable)/2+0.5;
    float b = sin(ourVariable*1.3)/2+0.5;
    float c = sin(ourVariable*1.9)/2+0.5;
    gl.glBegin( GL.GL_QUADS ); // we will draw a rectangle
    gl.glColor3f(a, 0.5, c);
    gl.glVertex3f( -0.3, 0.3f, -1 );
    gl.glColor3f(0.5, 1-a, b);
    gl.glVertex3f( -0.3, -0.3f, -1 );
    gl.glColor3f(c, 1-c, 1);
    gl.glVertex3f( 0.3, -0.3f, -1 );
    gl.glColor3f(c, b, a);
    gl.glVertex3f( 0.3, 0.3f, -1 );
    gl.glEnd();
    // ------------------------------------------
  }

  public void reshape(GLDrawable drawable, int x, int y, int width, int height)
  {
    // -------- this will be called whenever our openGL window is resized!
  }

  public void displayChanged(GLDrawable drawable, boolean modeChanged, boolean deviceChanged)
  {
    // -------- this is not implemented in JOGL yet. Best to leave it alone.
  }
}