Using the JOGLDisplaySystem wih and existing GLAutodrawable

archive contribution-depot-jme2
1

The following change allows the JOGLDisplaySystem to use a window (a GLAutodrawable) that was created outside of JME.  This is used within jMirrorWorld to allow JME to interact with the window created by World Wind.


### Eclipse Workspace Patch 1.0
Index: src/com/jme/system/jogl/JOGLDisplaySystem.java
===================================================================
--- src/com/jme/system/jogl/JOGLDisplaySystem.java   (revision 4479)
+++ src/com/jme/system/jogl/JOGLDisplaySystem.java   (working copy)
@@ -562,6 +562,62 @@
         gl.setSwapInterval(0);
     }
 
+    public GLContext createContext(GLAutoDrawable currentDrawable) {
+        if (autoDrawable != null)
+            throw new IllegalStateException();
+
+        width = currentDrawable.getWidth();
+        height = currentDrawable.getHeight();
+
+        autoDrawable = currentDrawable;
+
+        // Create the context reusing the existing surface. This creates a
+        // context just like the construction of a GLAutoDrawable such as
+        // a GLCanvas.
+        GLContext existingContext = currentDrawable.getContext();
+        GLContext context = autoDrawable.createContext(existingContext);
+        logger.info("AutoDrawable.createContext(" + existingContext + "): Error Code = "
+                + currentDrawable.getGL().glGetError());
+       
+        // Make the new context current so that OpenGL operations will use
+        // this context.
+        while (context.makeCurrent() == GLContext.CONTEXT_NOT_CURRENT) {
+            logger.info("GLContext.makeCurrent(): Error Code = "
+                    + currentDrawable.getGL().glGetError());
+           
+            try {
+                logger.info("Waiting for the GLContext to initialize...");
+                Thread.sleep(500);
+            } catch (InterruptedException interrupted) {
+                logger.log(Level.WARNING, "Interrupted", interrupted);
+            }
+        }
+
+        // Enable automatic checking for OpenGL errors.
+        // TODO Make this configurable, possibly from a system property.
+        // TODO Can this be centralized in createGLCanvas?
+        context.setGL(new DebugGL(context.getGL()));
+
+        // TODO Move this into the canvas, instead of grabbing the current
+        // current GLAutoDrawable, since this precludes multiple canvases.
+        // TODO UPDATE: Switch to context-based scenario.
+        JOGLContextCapabilities caps = new JOGLContextCapabilities(autoDrawable);
+        renderer = new JOGLRenderer(this, caps, width, height);
+
+        // This renderer is "headless" because someone else will be responsible
+        // for displaying back buffers, etc.
+        renderer.setHeadless(true);
+
+        // TODO switching to GLAutoDrawable as the key would allow this to be
+        // centralized. The other option is to move the context into the surface
+        // where it belongs.
+        currentContext = new RenderContext<GLContext>(context);
+        currentContext.setupRecords(renderer);
+        updateStates(renderer);
+
+        return context;
+    }
+
     @Override
     public boolean isActive() {
         // TODO Auto-generated method stub return false;

2

Is a so long sleep necessary?

Thread.sleep(500);

3

The length of time to wait before checking again for the GLContext to initialize could be changed.  I just looked, and found that the same basic code appears 3 times in JOGLDisplaySystem:


    while (contextKey.makeCurrent() == GLContext.CONTEXT_NOT_CURRENT) {
        try {
            logger.info("Waiting for the GLContext to initialize...");
            Thread.sleep(500);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }
    }



We could consolidate the code into a single internal method, and consider shortening the delay between checks.
4

cylab makes the same kind of call in ensureContextCurrent(). We will have to factorize this code.

5

You can submit the code as it is, we will do something cleaner later.

6
gouessej said:

You can submit the code as it is, we will do something cleaner later.
Are you sure that is a good idea?.. How will you assure that 'doing something cleaner later will ever happen?
7
erlend_sh said:

gouessej said:

You can submit the code as it is, we will do something cleaner later.
Are you sure that is a good idea?.. How will you assure that 'doing something cleaner later will ever happen?

We will factorize the source code once cylab will have finished his fixes. I will write a method that performs the operations common with cylab's and woody's fixes and I will replace the duplicated source code by a call of this method.