import java.awt.*;
import javax.swing.*;
import com.jogamp.opengl.*;
import com.jogamp.opengl.awt.*;


public class FirstTriangle extends GLJPanel implements GLEventListener{
    
    /**
     * A main routine to create and show a window that contains a
     * panel of type FirstTriangle.  The program ends when the
     * user closes the window.
     */
    public static void main(String[] args) {
        JFrame window = new JFrame("The Basic OpenGL RGB Triangle");
        FirstTriangle panel = new FirstTriangle();
        window.setContentPane(panel);
        window.pack();
        window.setLocation(50,50);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setVisible(true);
    }
    
    /**
     * Constructor for class FirstTriangle.
     */
    public FirstTriangle() {
        super( new GLCapabilities(null) ); // Makes a panel with default OpenGL "capabilities".
        setPreferredSize( new Dimension(500,500) );
        addGLEventListener(this); // A listener is essential! The listener is where the OpenGL programming lives.
    }
    
    
    //-------------------- GLEventListener Methods -------------------------

    /**
     * The display method is called when the panel needs to be redrawn.
     * The is where the code goes for drawing the image, using OpenGL commands.
     */
    public void display(GLAutoDrawable drawable) {    
        
        GL2 gl2 = drawable.getGL().getGL2(); // The object that contains all the OpenGL methods.
         
        gl2.glClearColor( 0, 0, 0, 1 );  // (In fact, this is the default.)
        gl2.glClear( GL2.GL_COLOR_BUFFER_BIT );
        
        gl2.glBegin(GL2.GL_TRIANGLES);
        gl2.glColor3d( 1, 0, 0 ); // red
        gl2.glVertex2d( -0.8, -0.8 );
        gl2.glColor3d( 0, 1, 0 ); // green
        gl2.glVertex2d( 0.8, -0.8 );
        gl2.glColor3d( 0, 0, 1 ); // blue
        gl2.glVertex2d( 0, 0.9 );
        gl2.glEnd(); 
        
    } // end display()

    public void init(GLAutoDrawable drawable) {
           // called when the panel is created
    }

    public void dispose(GLAutoDrawable drawable) {
            // called when the panel is being disposed
    }

    public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {
            // called when user resizes the window
    }
    
}