import javax.media.opengl.GL;
import javax.media.opengl.GLContext;
import javax.media.opengl.GLDrawable;
import javax.media.opengl.GLDrawableFactory;
import javax.media.opengl.glu.GLU;

import org.eclipse.swt.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.opengl.*;
import org.eclipse.swt.widgets.*;

public class JoglDemo {	
	static void drawTorus(GL 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;
		float cosTheta = 1.0f;
		float 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(GL.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;
		}
	}

	public static void main(String [] args) {
		final Display display = new Display();
		Shell shell = new Shell (display);
		shell.setLayout(new FillLayout());
		GLData data = new GLData ();
		data.doubleBuffer = true;
		final GLCanvas canvas = new GLCanvas (shell, SWT.NONE, data);
		canvas.setCurrent();
		
		GLDrawable drawable = GLDrawableFactory.getFactory().createExternalGLDrawable();
		GLContext context = drawable.createContext(null);
		GLContext.setCurrent(context);
		final GL gl = context.getGL ();
		System.out.println("GL_VENDOR: " + gl.glGetString(GL.GL_VENDOR));
		
		int width = 640, height = 480;
		float fAspect = (float) width / (float) height;

		gl.glViewport(0, 0, width, height);
		gl.glMatrixMode(GL.GL_PROJECTION);	// select the projection matrix
		gl.glLoadIdentity();				// reset the projection matrix
		GLU glu = new GLU();
		glu.gluPerspective(45.0f, fAspect, 0.5f, 400.0f);
		gl.glMatrixMode(GL.GL_MODELVIEW);	// select the modelview matrix
		gl.glLoadIdentity();
		gl.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
		gl.glColor3f(1.0f, 0.0f, 0.0f);
		gl.glHint(GL.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_NICEST);
		gl.glClearDepth(1.0);
		gl.glLineWidth(2);
		gl.glEnable(GL.GL_DEPTH_TEST);
		
		shell.setSize (640, 480);
		shell.open();
		
	    display.asyncExec(new Runnable() {
	    	int rot = 0;
			public void run() {
				if (!canvas.isDisposed()) {
					canvas.setCurrent();
					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 * ((float) rot), 10.0f * ((float) rot), 1.0f);
					gl.glRotatef(0.3f * rot, 3.0f * ((float) rot), 1.0f * ((float) rot), 1.0f);
					rot++;
					gl.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_LINE);
					gl.glColor3f(0.9f, 0.9f, 0.9f);
					drawTorus(gl, 1, 1.9f + ((float) Math.sin((0.004f * rot))), 15, 15);
					canvas.swapBuffers();

					display.asyncExec(this);
				}
			}
		});

		while (!shell.isDisposed()) {
			if (!display.readAndDispatch()) {
				display.sleep();
			}
		}
		display.dispose();
	}
}