package demos.nehe.lesson02;

/*
 * Lesson02.java
 *
 * Created on July 10, 2003, 2:33 PM
 */

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

/** Port of the NeHe OpenGL Tutorial (Lesson 2)
 * to Java using the Jogl interface to OpenGL.  Jogl can be obtained
 * at http://jogl.dev.java.net/
 *
 * @author Kevin Duling (jattier@hotmail.com)
 */
class Renderer implements GLEventListener {
    private GLU glu = new GLU();

    /** Called by the drawable to initiate OpenGL rendering by the client.
     * After all GLEventListeners have been notified of a display event, the
     * drawable will swap its buffers if necessary.
     * @param gLDrawable The GLAutoDrawable object.
     */
    public void display(GLAutoDrawable gLDrawable) {
        final GL gl = gLDrawable.getGL();
        gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
        gl.glLoadIdentity();
        gl.glTranslatef(-1.5f, 0.0f, -6.0f);
        gl.glBegin(GL.GL_TRIANGLES);		// Drawing Using Triangles
        gl.glVertex3f(0.0f, 1.0f, 0.0f);	// Top
        gl.glVertex3f(-1.0f, -1.0f, 0.0f);	// Bottom Left
        gl.glVertex3f(1.0f, -1.0f, 0.0f);	// Bottom Right
        gl.glEnd();				// Finished Drawing The Triangle
        gl.glTranslatef(3.0f, 0.0f, 0.0f);
        gl.glBegin(GL.GL_QUADS);           	// Draw A Quad
        gl.glVertex3f(-1.0f, 1.0f, 0.0f);	// Top Left
        gl.glVertex3f(1.0f, 1.0f, 0.0f);	// Top Right
        gl.glVertex3f(1.0f, -1.0f, 0.0f);	// Bottom Right
        gl.glVertex3f(-1.0f, -1.0f, 0.0f);	// Bottom Left
        gl.glEnd();				// Done Drawing The Quad
        gl.glFlush();
    }


    /** Called when the display mode has been changed.  <B>!! CURRENTLY UNIMPLEMENTED IN JOGL !!</B>
     * @param gLDrawable The GLAutoDrawable object.
     * @param modeChanged Indicates if the video mode has changed.
     * @param deviceChanged Indicates if the video device has changed.
     */
    public void displayChanged(GLAutoDrawable gLDrawable, boolean modeChanged, boolean deviceChanged) {
    }

    /** Called by the drawable immediately after the OpenGL context is
     * initialized for the first time. Can be used to perform one-time OpenGL
     * initialization such as setup of lights and display lists.
     * @param gLDrawable The GLAutoDrawable object.
     */
    public void init(GLAutoDrawable gLDrawable) {
        GL gl = gLDrawable.getGL();
        gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
        gl.glShadeModel(GL.GL_FLAT);
    }


    /** Called by the drawable during the first repaint after the component has
     * been resized. The client can update the viewport and view volume of the
     * window appropriately, for example by a call to
     * GL.glViewport(int, int, int, int); note that for convenience the component
     * has already called GL.glViewport(int, int, int, int)(x, y, width, height)
     * when this method is called, so the client may not have to do anything in
     * this method.
     * @param gLDrawable The GLAutoDrawable object.
     * @param x The X Coordinate of the viewport rectangle.
     * @param y The Y coordinate of the viewport rectanble.
     * @param width The new width of the window.
     * @param height The new height of the window.
     */
    public void reshape(GLAutoDrawable gLDrawable, int x, int y, int width, int height) {
        final GL gl = gLDrawable.getGL();

        if (height <= 0) // avoid a divide by zero error!
            height = 1;
        final float h = (float) width / (float) height;
        gl.glViewport(0, 0, width, height);
        gl.glMatrixMode(GL.GL_PROJECTION);
        gl.glLoadIdentity();
        glu.gluPerspective(45.0f, h, 1.0, 20.0);
        gl.glMatrixMode(GL.GL_MODELVIEW);
        gl.glLoadIdentity();
    }
}