[osg-users] Completely offscreen rendering using FBO?

[Jad Killian]

Hi,

I would like to not have a window at all when rendering. I managed to get offscreen rendering to work fine with a pixel buffer like in the osgscreencapture example. Viewer setup code:


Code:
osgViewer::Viewer viewer;

unsigned int width = 1;
	unsigned int height = 1;
	bool pbufferOnly = false;
	osg::ref_ptr<osg::GraphicsContext> pbuffer;
	{
		osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
		traits->x = 0;
		traits->y = 0;
		traits->width = width;
		traits->height = height;
		traits->red = 8;
		traits->green = 8;
		traits->blue = 8;
		traits->alpha = 8;
		traits->windowDecoration = false;
		traits->pbuffer = true;
		traits->doubleBuffer = false;
		traits->sharedContext = 0;
		traits->readDISPLAY();
		traits->setUndefinedScreenDetailsToDefaultScreen();

		pbuffer = osg::GraphicsContext::createGraphicsContext(traits.get());
		if (pbuffer.valid())
		{
			osg::notify(osg::NOTICE) << "Pixel buffer has been created successfully." << std::endl;
		}
		else
		{
			osg::notify(osg::NOTICE) << "Pixel buffer has not been created successfully." << std::endl;
		}

	}


if (pbuffer.valid())
	{
		osg::ref_ptr<osg::Camera> camera = new osg::Camera;
		camera->setGraphicsContext(pbuffer.get());
		camera->setViewport(new osg::Viewport(0, 0, width, height));
		GLenum buffer = pbuffer->getTraits()->doubleBuffer ? GL_BACK : GL_FRONT;
		camera->setDrawBuffer(buffer);
		camera->setReadBuffer(buffer);
		//camera->setFinalDrawCallback(new WindowCaptureCallback());

		viewer.addSlave(camera.get(), osg::Matrixd(), osg::Matrixd());

		viewer.realize();





However, on some devices I get the following error:

PixelBufferWin32::init(), Error: some wgl extensions not supported

So I thought maybe I should "upgrade" to FBOs. But I'm not sure how to do it. I know how to use FBOs to do Render-To-Texture, but I can't figure out how to use them instead of a window.

Cheers,
Jad[/code]

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http://forum.openscenegraph.org/viewtopic.php?p=75553#75553