Hi Robert, So, is for the render to image execution path, is the CameraNode rendering to an FBO and then glGetPixels is called, or is it to the framebuffer? The reason I ask is that I believe I set up the image like this:
_capImage->allocateImage(width, height, 1, GL_RGB, GL_FLOAT); _capImage->setInternalTextureFormat(GL_RGB16F_ARB); I specify it as the target, and I still get a clamped image. If I understood were the image is coming from, that may help. Is it the FB or is it an FBO (texture)? Also, is there a callback I can set up for the CameraNode that, when it is executed, the render context, whether it be FB or FBO, is still bound so that I may make my own glReadPixels, or better yet glGetTexImage, call? Thanks Robert, Brad --- RSC BDC > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:osg-users- > [EMAIL PROTECTED] On Behalf Of Robert Osfield > Sent: Monday, September 11, 2006 12:19 PM > To: osg users > Subject: Re: [osg-users] Render to Image still clamping > > Hi Brad, > > You need to sift through the OpenGL extension docs up on opengl.org's > extension registry for hints about the clamping behavior. By default > OpenGL clamps all colours to the 0 to 1 range. I recall there being > extensions that relax this, and certain pixel formats may do this by > default. > > Robert. > > > On 9/11/06, Brad Colbert <[EMAIL PROTECTED]> wrote: > > Hi folks, > > I was wondering if I could get a short description of how the render > to > image process works for a CameraNode. It appears that my images are > still clamped and digging through the code I see that glReadPixels > is > being called, but I also see a call for glGetTexImage, but I'm > unsure if > this is used. Can anyone shed light on how the CameraNode does it's > render to image? Also, is there a way to define a call back for a > CameraNode that is rendering to an FBO so that the texture is still > bound and then I can make the call to glGetTexImage. This would > save me > a ton of hassle > > Thanks, > Brad > > --- > RSC > BDC > > > -----Original Message----- > > From: Eric Sokolowsky [mailto:[EMAIL PROTECTED] > > Sent: Monday, September 11, 2006 9:58 AM > > To: Brad Colbert > > Cc: Eric Sokolowsky > > Subject: RE: [osg-users] OpenSceneGraph-1.1 Release Candidate this > week > > > > On Mon, 11 Sep 2006, Brad Colbert wrote: > > > > > Eric, > > > > > > Thanks, I'll keep poking around. I know it's not the drivers > because I > > > wrote a program in OpenGL as well as Vega Prime that downloads > the > > > images without alteration. One thing I did notice is that it > looks > like > > > glReadPixels is being used instead of glGetTexImage. I wonder > if > this > > > has something to do with it? > > > > This is probably the case. glReadPixels reads from the display > frame > > buffer which is probably NOT in a floating point format. > glGetTexImage > > reads > > from a texture image which can be stored on the graphics card in a > > floating > > point format. Your rasterization step will generate values 0-255 > which, > > when read back as floating point, will be converted from 0-1. > > > > I do not know much about FBOs but I presume that they similarly > are > > implemented as a RGB[A] 8-bit integer buffer. > > > > > > > > > > -B > > > > > > --- > > > RSC > > > BDC > > > > > >> -----Original Message----- > > >> From: Eric Sokolowsky [mailto:[EMAIL PROTECTED] > > >> Sent: Monday, September 11, 2006 8:59 AM > > >> To: Brad Colbert > > >> Cc: Eric Sokolowsky > > >> Subject: RE: [osg-users] OpenSceneGraph-1.1 Release Candidate > this > > > week > > >> > > >> On Mon, 11 Sep 2006, Brad Colbert wrote: > > >> > > >>> Hi Eric, > > >>> > > >>> There is still an issue with rendering to an image, where the > image > > > is > > >>> clamped at 1.0 (for a floating point destination). It's a > little > > >>> difficult to follow the thread of where the image is being > > > downloaded so > > >>> I'm not sure at what point it is being clamped. I know my > image > > > isn't > > >>> clamped in texture memory because when I change my destination > to > be > > > an > > >>> FBO and place a simple shader on the result that throws 0 - > 1.0 > into > > >>> blue, 1.0 - 2.0 into green, and 2.0 - 3.0 into red I get the > values > > > I > > >>> expect (blue fading into cyan and white). (BTW this basically > how > I > > >>> have to get the image out now). > > >> > > >> Hmm. I'm afraid this is a little outside my expertise. I have > not > yet > > >> tried out FBOs, and I haven't tried rendering to texture. I > highly > > > doubt > > >> that OSG is doing the clamping, so it is probably in the OpenGL > driver > > >> somewhere. This is a complete guess. Most of my work was to > help > read > > >> back compressed textures after they have been compressed by the > > > hardware > > >> and/or the OpenGL driver, in order to save them to disk for > reuse. > I > > >> probably won't be able to help you much with your issue. > > >> > > >> Perhaps you could ask your OpenGL driver vendor. > > >> > > >>> > > >>> I can modify the prerender example to do something similar if > that > > > will > > >>> help. > > >>> > > >>> Thanks, > > >>> Brad > > >>> > > >>> --- > > >>> RSC > > >>> BDC > > >>>> -----Original Message----- > > >>>> From: Eric Sokolowsky [mailto:[EMAIL PROTECTED] > > >>>> Sent: Monday, September 11, 2006 8:44 AM > > >>>> To: Brad Colbert > > >>>> Cc: osg users; Eric Sokolowsky > > >>>> Subject: RE: [osg-users] OpenSceneGraph-1.1 Release Candidate > this > > >>> week > > >>>> > > >>>> On Sat, 9 Sep 2006, Brad Colbert wrote: > > >>>> > > >>>>> Eric, > > >>>>> > > >>>>> Did your update or changes make it into the current tree? > I'm > > > still > > >>>>> having the same problem of clamping when trying to capture > an > FP16 > > >>>>> image. If not, what changes did you make? This is really a > show > > >>>>> stopper for me, since I need unclamped values to get the > real > > >>> statistics > > >>>>> from my HDR scene. > > >>>> > > >>>> Yes, my changes made it into CVS. The > > >>>> osg::Image::readImageFromCurrentTexture > > >>>> API function now has an optional parameter at the end which > defines > > >>> the > > >>>> type to > > >>>> be used when reading. If not given it will default to > > >>> GL_UNSIGNED_BYTE. > > >>>> It > > >>>> turns out that this value is not stored by OpenGL anywhere; > it > just > > >>> reads > > >>>> and > > >>>> converts whatever is there to the format requested. I have > also > > > fixed > > >>> some > > >>>> state inconsistencies when reading textures this way. > > >>>> > > >>>> I believe the changes I made are sufficient for my purposes, > but > if > > >>> there > > >>>> is something else that needs to be done, I am willing to look > again > > > at > > >>> it. > > >>>> > > >>>>> > > >>>>> Thanks, > > >>>>> Brad > > >>>>> > > >>>>> --- > > >>>>> RSC > > >>>>> BDC > > >>>>> > > >>>>>> -----Original Message----- > > >>>>>> From: [EMAIL PROTECTED] <mailto:osg- > [EMAIL PROTECTED]> [mailto:osg-users- > > >>>>>> [EMAIL PROTECTED] On Behalf Of Eric Sokolowsky > > >>>>>> Sent: Wednesday, July 05, 2006 2:48 PM > > >>>>>> To: osg users > > >>>>>> Subject: Re: [osg-users] OpenSceneGraph-1.1 Release > Candidate > > > this > > >>>>> week > > >>>>>> > > >>>>>> On Wed, 5 Jul 2006, Robert Osfield wrote: > > >>>>>> > > >>>>>>> Hi Eric, > > >>>>>>> > > >>>>>>> On 7/5/06, Eric Sokolowsky <[EMAIL PROTECTED]> > > > wrote: > > >>>>>>>> I have determined that when reading a texture back, > > >>>>> Image::_pixelFormat > > >>>>>>>> and Image::_internalTextureFormat should be set to the > same > > >>> value, > > >>>>>> which > > >>>>>>>> is obtained with a call to > > > glGetTexLevelParameteriv(textureMode, > > >>> 0, > > >>>>>>>> GL_TEXTURE_INTERNAL_FORMAT, ...). That is fine. But I > still > > >>> haven't > > >>>>>>>> found a way to get the pixel format from OpenGL. Perhaps > we > > > need > > >>> to > > >>>>> add > > >>>>>>>> something to the osg::State to track this. > > >>>>>>> > > >>>>>>> I'm afraid I'm too cold on this topic to provide much > insight. > > >>>>>> > > >>>>>> Well, the call to glGetTexImage() asks for a format and a > type. > > > The > > >>>>>> format parameter can be obtained from OpenGL, but the type > cannot > > >>> be. > > >>>>>> Therefore, it seems reasonable to add a "type" argument to > > >>>>>> osg::Image::readImageFromCurrentTexture, instead of > arbitrarily > > >>>>> mandating > > >>>>>> one type or another. The current implementation is buggy in > that > > > it > > >>>>>> sets the type parameter to the same internal format that is > used > > > as > > >>>>> the > > >>>>>> format parameter. > > >>>>>> > > >>>>>> This should also help Brad Colbert with his texture read > > > precision > > >>>>>> problem. > > >>>>>> > > >>>>>> A changed file is forthcoming. > > >>>>>> > > >>>>>> > > >>>>>>>> BTW, the set of images I was having trouble with were not > a > > >>>>> multiple of > > >>>>>>>> four in size. OpenGL will report an error when trying to > use > a > > >>>>>>>> compressed texture with glTexSubImage2D() if the > subloaded > > >>> texture > > >>>>> is > > >>>>>>>> not of a multiple of four in both dimensions. Is this > something > > >>>>> that > > >>>>>>>> should be checked for by OSG? I have a workaround in my > > >>> application > > >>>>>> that > > >>>>>>>> will disable texture compression on images that are not a > > >>> multiple > > >>>>> of > > >>>>>>>> four in size. > > >>>>>>> > > >>>>>>> I believe the limit of a multiple of 4 is something > related to > > > the > > >>>>>>> S3TC compression where it uses blocks of pixels as its > block > to > > > do > > >>>>> the > > >>>>>>> compression. > > >>>>>> > > >>>>>> Yes, this is exactly the reason. The question is, is it > > > worthwhile > > >>>>> coding > > >>>>>> a check for this condition in OSG? I don't want to code it > if > it > > >>>>> stands > > >>>>>> little success for inclusion in OSG proper. I already have > a > > >>>>> workaround > > >>>>>> for > > >>>>>> my application that deals with this situation, but the > general > > >>>>> solution > > >>>>>> might be useful to others as well. The change would merely > > > disable > > >>> the > > >>>>>> compression request for images that are not a multiple of > four > in > > >>>>> either > > >>>>>> dimension, when glTexSubImage2D() is called. > > >>>>>> > > >>>>>> -- > > >>>>>> ____ __ Eric Sokolowsky (GST) NASA Goddard > Space > > >>> Flight > > >>>>>> Center > > >>>>>> / __/__/_/__ Visualization Programmer Scientific > > >>> Visualization > > >>>>>> Studio > > >>>>>> / __/ _/ / _/ 301.286.3751 Mailstop > 610.3 > > > Bldg > > >>> 28 > > >>>>> Rm > > >>>>>> E102 > > >>>>>> /___/_//_/__/ [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> Greenbelt, MD > > > 20771 > > >>>>>> _______________________________________________ > > >>>>>> osg-users mailing list > > >>>>>> [email protected] > > >>>>>> http://openscenegraph.net/mailman/listinfo/osg-users > > >>>>>> http://www.openscenegraph.org/ > > >>>>> > > >>>> > > >>>> -- > > >>>> ____ __ Eric Sokolowsky (GST) NASA Goddard > Space > > > Flight > > >>>> Center > > >>>> / __/__/_/__ Visualization Programmer Scientific > > > Visualization > > >>>> Studio > > >>>> / __/ _/ / _/ 301.286.3751 Mailstop 610.3 > Bldg > > > 28 > > >>> Rm > > >>>> E102 > > >>>> /___/_//_/__/ [EMAIL PROTECTED] Greenbelt, > MD > 20771 > > >>> > > >> > > >> -- > > >> ____ __ Eric Sokolowsky (GST) NASA Goddard Space > Flight > > >> Center > > >> / __/__/_/__ Visualization Programmer Scientific > Visualization > > >> Studio > > >> / __/ _/ / _/ 301.286.3751 Mailstop 610.3 > Bldg > 28 > > > Rm > > >> E102 > > >> /___/_//_/__/ [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> Greenbelt, MD 20771 > > > > > > > -- > > ____ __ Eric Sokolowsky (GST) NASA Goddard Space > Flight > > Center > > / __/__/_/__ Visualization Programmer Scientific > Visualization > > Studio > > / __/ _/ / _/ 301.286.3751 Mailstop 610.3 Bldg > 28 > Rm > > E102 > > /___/_//_/__/ [EMAIL PROTECTED] Greenbelt, MD > 20771 > _______________________________________________ > osg-users mailing list > [email protected] > http://openscenegraph.net/mailman/listinfo/osg-users > <http://openscenegraph.net/mailman/listinfo/osg-users> > http://www.openscenegraph.org/ > > _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
