Chuck, You have to define the camera as an FBO as well as attaching an image as a target:
camera->setRenderTargetImplementation(osg::CameraNode::FRAME_BUFFER_OBJE CT); Normally the camera renders to a standard OGL frame buffer which will clamp the values when red back into the osg::Image. The above should fix that. -Brad --- RSC BDC > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:osg-users- > [EMAIL PROTECTED] On Behalf Of Chuck Seberino > Sent: Tuesday, October 03, 2006 11:20 AM > To: 'osg users' > Subject: RE: [osg-users] Retrieving texture contents from ARB float FBO > RTT > > Robert, > > > > I worked with osgprerender to see if I could get the osg::Image readback > to work. Unfortunately it seems that using that approach, versus > attaching a texture, causes the results to be clamped to within [0,1]. > The whole reason for using the ARB format and FBO was to get the full > floating point range. I believe that using a texture attachment is the > only way around the clamping. > > > > Aside from patching osg::Image to properly handle the ARB texture format, > my only course seems to be using glReadPixels while the FBO Texture is > active. I looked into this, but like I said before, there doesn't seem to > be an easy (clean) way to get this. I have a post draw for the camera > node that has access to the SceneView pointer. From there I can get the > RenderStage. My camera is being drawn in a preRender, so it's RenderStage > is tucked into the preRenderList - of which there is no public access. > There doesn't seem to be a way for me to get the fbo handle so that I can > enable it and read the texels. > > > > Looking at the code for RenderStage, there already seems to be code ready > to do glReadPixels. I just need to give it a valid osg::Image via > setImage. So it looks like my big holdup is in figuring out and acquiring > the RenderStage handle that applies to my CameraNode. Any suggestions? > > > > Chuck > > -----Original Message----- > From: Robert Osfield [mailto:[EMAIL PROTECTED] > Sent: Monday, October 02, 2006 1:25 AM > To: osg users > Subject: Re: [osg-users] Retrieving texture contents from ARB float FBO > RTT > > > > Hi Chuck, > > On 10/2/06, Chuck Seberino <[EMAIL PROTECTED]> wrote: > > I have some code that sets up a CameraNode with a FBO as the target. The > texture attached to the FBO has a format of GL_RGB32F_ARB. This seems to > work just great. > > The problem is that I want to be able to read in the value of the texture > as an osg::Image after drawing. I have used image- > >readImageFromCurrentTexture(), but osg::Image doesn't know about the ARB > formats when performing the bit size calculations. Is this a deficiency > in computNumComponents() or is there something I am missing? Even hacking > that method to calculate it correctly doesn't solve things. I didn't get > a chance to dig deeper to see what the next roadblock was. > > > Missing support for the ARB pixel formats is obviously one missing element > that will need addressing, as for what other gotcha's could be causing > problems its hard to point point without digging into to debugging myself. > > > > Is there a better way to grab the texture back into main memory? In > OpenGL-land I would call glReadPixels while the FBO was active, but there > doesn't seem to be an easy way to do that in OSG either. > > > The osgprerender example provides a path that attaches an osg::Image to > the CameraNode, and this gets read back in automatically so you can > probably use this. There is also support for post draw callback on > CameraNode that you could use to implement your own glReadPixels call. > > Could you modify osgprerender to use the pixel format you are having > problem with and if this recreates the problem then send the modified file > along to me and I'll have a go at debugging it. > > Robert. _______________________________________________ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
