LWJGL Forum

Hi!

I am trying to use SWT in harmony with LWJGL and I am a little confused how this should be done correctly.

I would like the canvases to be very similar or even identical if that helps to reduce waste of memory.

Thanks!

I have "solved" the problem by reusing a single canvas in a modified GUI design. It might be good to have an SWT snippet for multiple GLCanvases though. I don't know if any of you have been working with the SWT project, so I might have posted this in the wrong forum :P Thanks anyway for this great piece of software, I will remember to donate in christmas :)

You can use multiple canvases. Just set the current cavas to be the current gl contex before you draw each one like so:



package com.tscribble.game.examples.swtopengl;

import static org.lwjgl.opengl.GL11.*;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.*;

import com.tscribble.game.opengl.swt.GLComposite2D;

/**
* @author triston
*
*/
public class SWTMultiComposite {

private Display display;
private GLComposite2D canvas,canvas2;
private float ang,ang2 = 0;

public static void main(String[] args) {
SWTMultiComposite window = new SWTMultiComposite();
window.open();
}

public void open() {
display = Display.getDefault();
Shell shell = new Shell();
shell.setSize(1024, 600);
shell.setText("SWT GL Mutiple Composites");
shell.setLayout(new FillLayout(SWT.HORIZONTAL));

Menu mBar = new Menu(shell, SWT.BAR);
shell.setMenuBar(mBar);

MenuItem fileItem = new MenuItem(mBar, SWT.CASCADE);
fileItem.setText("File");

Menu fileMenu = new Menu(fileItem);
fileItem.setMenu(fileMenu);

for (int i = 0; i < 5; i++) {
final MenuItem importItem = new MenuItem(fileMenu, SWT.NONE);
importItem.setText("Item " + i);
}

canvas = new GLComposite2D(shell);
canvas.addListener(SWT.Resize, new Listener() {
public void handleEvent(Event event) {
doResize(canvas);
}});

canvas2 = new GLComposite2D(shell);
canvas2.addListener(SWT.Resize, new Listener() {
public void handleEvent(Event event) {
doResize(canvas2);
}});

shell.open();
start(); // render loop thread

while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
protected void initGL() {
glShadeModel(GL_SMOOTH); // Enable Smooth Shading, GL_SMOOTH (the default) or GL_FLAT.
}

private void doResize(GLComposite2D comp) {
Rectangle rec = comp.getBounds();
float w = Math.max(rec.width, 1);
float h = Math.max(rec.height, 1);

comp.makeCurrent();

glViewport(0, 0, (int) w, (int) h);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

glOrtho(0, w, h, 0, 1, -1);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

public void start() {
display.syncExec(new Runnable() {
public void run() {
if (!canvas.isDisposed() || !canvas2.isDisposed()) {
try {Thread.sleep(10);}catch (InterruptedException e){}
logic();
logic2();

canvas.makeCurrent();
draw();

canvas2.makeCurrent();
draw2();

canvas.swapBuffers();
canvas2.swapBuffers();

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

public void logic() {
ang += 0.5f % 360;
}

public void logic2() {
ang2 -= 0.5f % 360;
}

private void draw() {
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(1.0f, 0.0f, 0.0f, 0.0f);  // Red Background

glPushMatrix();
{
glTranslatef(10, 10, 0);
glBegin(GL_TRIANGLES);
glColor3f(1.0f, 0.0f, 0.0f); // red
glVertex2f(5.0f, 5.0f);

glColor3f(0.0f, 1.0f, 0.0f); // green
glVertex2f(400.0f, 5.0f);

glColor3f(0.0f, 0.0f, 1.0f); // blue
glVertex2f(5.0f, 400.0f);
glEnd();
}
glPopMatrix();
}

private void draw2() {
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0.0f, 0.0f, 1.0f, 0.0f);  // Blue Background

glPushMatrix();
{
glTranslatef(10, 10, 0);
glBegin(GL_TRIANGLES);
glColor3f(1.0f, 0.0f, 0.0f); // red
glVertex2f(5.0f, 5.0f);
glColor3f(0.0f, 1.0f, 0.0f); // green
glVertex2f(100.0f, 5.0f);
glColor3f(0.0f, 0.0f, 1.0f); // blue
glVertex2f(5.0f, 100.0f);
glEnd();
}
glPopMatrix();
}

}


The GLComposite

package com.tscribble.game.opengl.swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.opengl.GLCanvas;
import org.eclipse.swt.opengl.GLData;
import org.eclipse.swt.widgets.*;
import org.lwjgl.LWJGLException;

import org.lwjgl.opengl.*;

/**
* @author triston
*/
public class GLComposite2D extends GLCanvas {
private static GLData gd1;
protected Rectangle rec;

static {
gd1 = new GLData();
gd1.doubleBuffer = true;
}

public GLComposite2D(Composite parent) {
super(parent, SWT.NONE, gd1);
}

public void makeCurrent() {
setCurrent();
try {
GLContext.useContext(this);
} catch (LWJGLException e) {
e.printStackTrace();
}
}
}


hope that helps