Pure Offscreen Rendering

OpenGL Development JOGL Development
#1

I want to use JOGL 2.x for a console/terminal based image manipulation program without any GUI/window. Unfortunately, I don’t find a way to create and opengl context easily.

I know there are pbuffers, but AFAIK these are platform dependent and not very flexible in the format (floating point formats only?). That is why I use a framebuffer object with a texture2D as color component. That works fine, but it seems I still need a window or pbuffer to create the GLContext. Currently, I use a 1x1 sized pbuffer to get an ‘offscreen’ opeengl context like this:


GLCapabilities caps = new GLCapabilities(GLProfile.getDefault());
caps.setDoubleBuffered(false);

GLCapabilitiesChooser capsChooser = new DefaultGLCapabilitiesChooser();
GLPbuffer pBuffer = GLDrawableFactory.getFactory(GLProfile.getDefault()).createGLPbuffer(caps, capsChooser, 1, 1, null);

GLContext context = pBuffer.getContext();
context.makeCurrent();

GL gl = context.getGL();

// my offscreen rendering code goes here

context.destroy();

Is this necessary or can I create an opengl context without a pbuffer (and window)?

#2

A pbuffer is probably what you want, most platforms support them and they have plenty of available formats. The 1x1 pbuffer is something I do when multiple contexts need to be shared. For your case, though, since you’re depending on pbuffer support you might as well use pbuffers. More GPUs will support them than FBOs.

#3

thanks for answering!

I hoped pure FBO rendering would be possible (like on the iPhone/Pod/Pad). Guess I stick stick to my 1x1 pbuffer, because I don’t like passing the PBuffer class into the ‘real’ code :slight_smile: