Hi all, I have been playing a bit with osgPPU, and I have a couple of questions/issues. Note that I am on the last stable reelase, that is 0.4, so I don't know if there are more recent changes in the trunk that might fix these things. The main problem I have is with the HDR example, which I believe does not behave correctly. I'm referring to the osgppu_hdr example for my tests. The tone-mapping part has some problems and after some analysis I think it comes from the average luminance computation. To check that a problem is there, try disabling the temporal adaptation from the luminance_adapted_fp.glsl shader (just change it at the end so to set "lum = current"). This way the instant average luminance will be used for the tone mapping operations. Then run the program, display the average luminance result with F5; then zoom out so to reduce a bit the teapot. Try then panning around so to move the teapot in different parts of the image and you will see sudden changes in the luminance values, which are not correct. The shader tries to read the last value of the mipmapped texture for the sceneLuminance unit. But from what I see, it looks like this does not work and it actually reads the zero level, i.e. the full texture. In fact, when you move the teapot around keep an eye on what's in the center of the image: the shader samples at (0.5, 0.5)... When nothing is there you'll get a black luminance (well, a dark gray, there is a lower clamping at 0.2 in the shader). An additional test you can do to verify the problem is to change the sampling point of the texture from (0.5, 0.5) to anything else. If you are reading the last mipmap level (1x1 texture) this should always retrieve the same value, while it doesn't.
Does anybody know if this is really the problem I see? If it is, any solution or any idea about how to address it? Thanks, Luca ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=27189#27189 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
