/*******************************************************************************
 * Copyright (c) 2000, 2005, 2010 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Sven Gothel     - conversion to JOGL 2.0 (original at http://github.com/sgothel/jogl-demos/blob/master/src/demos/swt/Snippet209.java)
 *     Wade Walker     - conversion to an Eclipse ViewPart
 *     
 *******************************************************************************/

package name.wadewalker.tutorial;

/*
 * SWT OpenGL snippet: use JOGL to draw to an SWT GLCanvas
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 * 
 * @since 3.2
 */
import javax.media.opengl.GL;
import javax.media.opengl.GL2;
import javax.media.opengl.GL2ES1;
import javax.media.opengl.GL2GL3;
import javax.media.opengl.GLContext;
import javax.media.opengl.GLDrawableFactory;
import javax.media.opengl.GLProfile;
import javax.media.opengl.fixedfunc.GLMatrixFunc;
import javax.media.opengl.glu.GLU;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.opengl.GLCanvas;
import org.eclipse.swt.opengl.GLData;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.part.ViewPart;

public class JOGLView extends ViewPart {

    /** Holds the OpenGL canvas. */
    private Composite composite;

    /** Widget that displays OpenGL content. */
    private GLCanvas glcanvas;

    /** Used to get OpenGL object that we need to access OpenGL functions. */
    private GLContext glcontext;

    /** Master rotation angle of the torus, in degrees. */
    private int rot = 0;

    public JOGLView() {
    }

    @Override
    public void createPartControl( Composite compositeParent ) {
        GLProfile glprofile = GLProfile.get(GLProfile.GL2);

        composite = new Composite( compositeParent, SWT.NONE );
        composite.setLayout( new FillLayout() );

        GLData gldata = new GLData();
        gldata.doubleBuffer = true;
        glcanvas = new GLCanvas( composite, SWT.NO_BACKGROUND, gldata );
        glcanvas.setCurrent();
        glcontext = GLDrawableFactory.getFactory( glprofile ).createExternalGLContext();

        glcanvas.addListener(SWT.Resize, new Listener() {
            public void handleEvent(Event event) {
                Rectangle bounds = glcanvas.getBounds();
                float fAspect = (float) bounds.width / (float) bounds.height;
                glcanvas.setCurrent();
                glcontext.makeCurrent();
                GL2 gl = glcontext.getGL().getGL2();
                gl.glViewport(0, 0, bounds.width, bounds.height);
                gl.glMatrixMode(GLMatrixFunc.GL_PROJECTION);
                gl.glLoadIdentity();
                GLU glu = new GLU();
                glu.gluPerspective(45.0f, fAspect, 0.5f, 400.0f);
                gl.glMatrixMode(GLMatrixFunc.GL_MODELVIEW);
                gl.glLoadIdentity();
                glcontext.release();
                }
        });

        glcontext.makeCurrent();
        GL2 gl = glcontext.getGL().getGL2();
        gl.setSwapInterval(1);
        gl.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
        gl.glColor3f(1.0f, 0.0f, 0.0f);
        gl.glHint(GL2ES1.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_NICEST);
        gl.glClearDepth(1.0);
        gl.glLineWidth(2);
        gl.glEnable(GL.GL_DEPTH_TEST);
        glcontext.release();

        (new Thread() {
            public void run() {
                while( (glcanvas != null) && !glcanvas.isDisposed() ) {
                    render();
                    try {
                        // don't make loop too tight, or not enough time
                        // to process window messages properly
                        sleep( 1 );
                    } catch( InterruptedException interruptedexception ) {
                        // we just quit on interrupt, so nothing required here
                    }
                }
            }
        }).start();
    }

    protected void render() {
        PlatformUI.getWorkbench().getDisplay().syncExec( new Runnable() {
            public void run() {
                if( (glcanvas != null) && !glcanvas.isDisposed()) {
                    glcanvas.setCurrent();
                    glcontext.makeCurrent();
                    GL2 gl = glcontext.getGL().getGL2();
                    gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
                    gl.glClearColor(.3f, .5f, .8f, 1.0f);
                    gl.glLoadIdentity();
                    gl.glTranslatef(0.0f, 0.0f, -10.0f);
                    gl.glRotatef(0.15f * rot, 2.0f * rot, 10.0f * rot, 1.0f);
                    gl.glRotatef(0.3f * rot, 3.0f * rot, 1.0f * rot, 1.0f);
                    rot++;
                    gl.glPolygonMode(GL.GL_FRONT_AND_BACK, GL2GL3.GL_LINE);
                    gl.glColor3f(0.9f, 0.9f, 0.9f);
                    drawTorus(gl, 1, 1.9f + ((float) Math.sin((0.004f * rot))), 15, 15);
                    glcanvas.swapBuffers();
                    glcontext.release();
                }
            }
        });
    }

    protected void drawTorus(GL2 gl, float r, float R, int nsides, int rings) {
        float ringDelta = 2.0f * (float) Math.PI / rings;
        float sideDelta = 2.0f * (float) Math.PI / nsides;
        float theta = 0.0f, cosTheta = 1.0f, sinTheta = 0.0f;
        for (int i = rings - 1; i >= 0; i--) {
            float theta1 = theta + ringDelta;
            float cosTheta1 = (float) Math.cos(theta1);
            float sinTheta1 = (float) Math.sin(theta1);
            gl.glBegin(GL2.GL_QUAD_STRIP);
            float phi = 0.0f;
            for (int j = nsides; j >= 0; j--) {
                phi += sideDelta;
                float cosPhi = (float) Math.cos(phi);
                float sinPhi = (float) Math.sin(phi);
                float dist = R + r * cosPhi;
                gl.glNormal3f(cosTheta1 * cosPhi, -sinTheta1 * cosPhi, sinPhi);
                gl.glVertex3f(cosTheta1 * dist, -sinTheta1 * dist, r * sinPhi);
                gl.glNormal3f(cosTheta * cosPhi, -sinTheta * cosPhi, sinPhi);
                gl.glVertex3f(cosTheta * dist, -sinTheta * dist, r * sinPhi);
            }
            gl.glEnd();
            theta = theta1;
            cosTheta = cosTheta1;
            sinTheta = sinTheta1;
        }
    }

    @Override
    public void setFocus() {
    }

    @Override
    public void dispose() {
        glcanvas.dispose();
        super.dispose();
    }
}
