Re: [platform-swt-dev] SWT-OpenGL rendering in different thread

[Paul Anderson <paul-anderson@xxxxxxxxxx>]

Hi

A few years ago I was looking for a
way to render many 2D primitives quickly, I had profiled SWT and noticed
that it naturally crosses JNI on every draw call and there is a large around
this.....

I imagined a batch interface in which
primitive draw instructions and their parameters are placed in an int/float
array and passed in bulk to the native code for rendering .... I'm going
to resurrect that idea shortly to see what happens.

int[] batch = { SWT.DRAW_LINE, 0,0,100,100,
SWT.FILL_CIRCLE, SWT.BLACK, 0,0,200,200  . . . . . . . };
display.render(batch);


OpenGL may well be able to use the same
mechanism and it is based on similar concepts ,one could then render in
a different thread, then just throw the batch(ogl scene) over to the native
code on a designated rendering thread.



Paul Anderson
Java Performance Principal
Banking Center of Excellence

Mobile:+31-651788098 (preferred),  Home Office:+31-70-362-9501, Office:+31-20-513-7388,
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From:	Junglas Bodo <junglas@xxxxxxxxxxxxx>
To:	platform-swt-dev@xxxxxxxxxxx
Date:	10/20/2009 09:55
Subject:	[platform-swt-dev] SWT-OpenGL rendering in different thread
Sent by:	platform-swt-dev-bounces@xxxxxxxxxxx

---

Hi there,

at the moment I'm experimenting with the GLCanvas and asked myself why
 
the access to the OpenGL context is so tightly restricted to the  
Display thread.
More precisely: I would like to do all the OpenGL rendering in a  
background thread without affecting the rest of the UI at all.  
Granted, it's usually a bad idea to mess around with OpenGL in  
multiple threads, but I was thinking about some kind of weighted  
execution queue that would allow me to render some views with higher  
priority than others and of course without blocking any kind of user  
interaction.

As a pure experiment I did this:
Extended the GLCanvas in my own project (boldly called this  
ExtGLCanvas) and just overrided the checkWidget() method by a weaker  
variant that only checks isDisposed. Then I simply handed all  
rendering stuff previously done via Display.asyncExecute() to a  
SingleThreadPoolExecutor.
At least with SWT OSX-Cocoa this seems to work like a charm.

So my question is: Am I missing an important point here?

Greets

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