Thanks. I tried this glReadBuffer command but mistakenly used: glReadBuffer(itr->first) instead of glReadBuffer(GL_COLOR_ATTACHMENT0_EXT + (itr->first - osg::CameraNode::COLOR_BUFFER0)
thanks a lot, u have enlightened me :) Guy. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of J.P. Delport Sent: Wednesday, February 13, 2008 12:05 PM To: OpenSceneGraph Users Subject: Re: [osg-users] MRT Hi, I'm afraid I cannot answer your question without looking at exactly at what I've done, so I'm just supplying you with an example that worked for me. It allowed read back of >1 float textures. I also attach the original email. There were modified patches sent after this email to submissions (I think by John Donovan), but it still needed work. Time... cheers jp original mail: ----8<---- Subject: Re: [osg-users] Multiple render targets Date: Fri, 14 Sep 2007 14:53:04 +0200 From: J.P. Delport <[EMAIL PROTECTED]> To: OpenSceneGraph Users <[email protected]> References: <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> Hi, OK, here goes. Attached you will find a modified RenderStage.cpp. I see that I modified OSG version 6386, so hopefully you can merge the changes with the latest SVN version. RenderStage lives in src/osgUtil. You can either look at the diff to latest version, or search for "JP" in the file. The hacky part is this: You call in your code e.g. camera->setDrawBuffer(GL_COLOR_ATTACHMENT3_EXT); this sets up 4 draw buffers, 0 to 3. If you call e.g. camera->setDrawBuffer(GL_COLOR_ATTACHMENT1_EXT); it will set up 2 buffers. You must also call camera->setReadBuffer(GL_COLOR_ATTACHMENT0_EXT); for enabling readback. You can attach readback images as per normal (>1 possible), see the example I attach. The example shows how I used MRT with 4 textures with floats, one shader just creates 4 textures, the other combines them again. What needs to be done to get to a patch: In short, I'm abusing GL_COLOR_ATTACHMENT* values to get my intention to use MRT into RenderStage. We need some mechanism to store/assign more than one drawbuffer inside "camera" and possibly a flag to indicate we want MRT. RenderStage can then inherit/query these values to properly call glDrawBuffer(s). If you have time, give it a bash. cheers jp Guy wrote: > Hello all, > > I've read in the mailing list that some people made some patches to use > MRT. > > I also did the same, instead of changing the RenderStage, I changed the > FrameBufferObject apply function (does MRT possible without FBO??) > > Anyway, the textures I attach to get the right values, but the images I > attach do not. > > In RenderStage, only the last image of the camera attachments is being > copied with readPixels. > > So I patched the RenderStage too, going over all camera attachments and > trying to read the images. But readPixels read from the frame buffer, so > for those attachments I attached also a texture and applied the texture > with the state of the renderstage, and then tried readFromCurrentTexture > (with fixing the image class to read correctly when using float) but the > images data was the same (the data on the frame buffer) even that the > textures where different. > > > > Can anyone explain how to read the data to the images (or any other way > to get the data from the MRT to the RAM)? > > > > Thanks, > > Guy. > > > ------------------------------------------------------------------------ > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.or g -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
