import javax.media.opengl.*;
import javax.media.opengl.glu.*;
import javax.swing.*;

/**
 * @author quix0r
 *
 */
public class Line extends JFrame implements GLEventListener {

   /**
    * 
    */
   private static final long serialVersionUID = -1445174150957788549L;
   /**
    * 
    */
   public Line()
   {
      // the name of the window
      super("My First JOGL Application"); //$NON-NLS-1$

      // create the canvas we will be drawing on
      final GLCanvas canvas = new GLCanvas();

      // as this class implements the GLEventListener interface
      // it is what tells the canvas what to do.
      canvas.addGLEventListener( this ); // VERY IMPORTANT LINE

      // set the size of the canvas
      canvas.setSize(500, 300);

      // add the canvas to the window
      this.getContentPane().add(canvas);
   }
   /**
    *  This is the initialisation method. It is used to set up several of the
    *  state variables that are constant for the programs duration
    */
   public void init(final GLAutoDrawable drawable)
   {
      // the GL object is used to set the state variables
      final GL gl = drawable.getGL();

      // the GLU object can do alot of complex things
      // but there it is used to simply set up the coordinates
      // for the drawing area.
      final GLU glu = new GLU();

      // this sets the background colour to black
      // the first three numbers are the specification
      // of black in RGB, and the last is an alpha component.
      gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

      // sets the size of the viewable drawing area on the screen
      gl.glViewport(-500, -300, 500, 300);

      // dont worry too much about these
      gl.glMatrixMode(GL.GL_PROJECTION);
      gl.glLoadIdentity();

      // set the coordinate system. Its is set so that (0,0) is the centre of the canvas.
      // (-500, -300) is the bottom left corner.
      glu.gluOrtho2D(-500, 500.0, -300, 300.0);
   }
   /**
    * This method draws the red line that was mentioned in the tutorial
    * @param drawable 
    */
   public void display(final GLAutoDrawable drawable)
   {
      // again we need the object representing the state of oplenGL
      final GL gl = drawable.getGL();

      // we earlier set the background colour, now we paint that
      // colour onto our canvas.
      gl.glClear(GL.GL_COLOR_BUFFER_BIT);

      // these are used to represent the RGB values for a colour
      // it isnt really necessary to use them in a program as simple as
      // this, but it is good practice.
      final float red = 1.0f;
      final float green = 0.0f;
      final float blue = 0.0f;

      // set the drawing colour to red.
      gl.glColor3f(red, green, blue);

      // set the width a line
      gl.glLineWidth(5.0f);

      // tell open gl to draw a line
      gl.glBegin(GL.GL_LINES);
         // from (-200, -200) to (200, 200)
         gl.glVertex2i(-200, -200);
         gl.glVertex2i(200, 200);
      gl.glEnd();
   }
   
   /*************************************************************
    * This has nothing to do with jogl, it is simply setting up the 
    * window that the canvas will be inside.
    * @param argv 
    */
   public static void main(final String[] argv)
   {
      final Line m = new Line();
      SwingUtilities.invokeLater 
      (
         new Runnable() 
         {
            public void run() 
            {
               m.pack();
               m.setVisible(true);
            }
         }
      );
   }
   /* (non-Javadoc)
    * @see javax.media.opengl.GLEventListener#displayChanged(javax.media.opengl.GLAutoDrawable, boolean, boolean)
    */
   public void displayChanged(final GLAutoDrawable arg0, final boolean arg1, final boolean arg2) {
      // TODO Auto-generated method stub
      
   }
   /* (non-Javadoc)
    * @see javax.media.opengl.GLEventListener#reshape(javax.media.opengl.GLAutoDrawable, int, int, int, int)
    */
   public void reshape(final GLAutoDrawable arg0, final int arg1, final int arg2, final int arg3, final int arg4) {
      // TODO Auto-generated method stub
      
   }
}