Hi Scott, The compression code has been in place quite some while so I'm surprised to see a report of problem now. Did this work with previous drivers/OSG versions/different hardware?
Could you provide a small example and explanation of how to reproduce it so others can see if they can reproduce the problem? Thanks, Robert. On 22 September 2015 at 20:51, Davis, Timothy S CTR comnavairsyscom < [email protected]> wrote: > I had an issue with OSG 3.4.0 when using a compressed 32x32 texture > causing an INVALID_OPERATION in Texture::applyTexImage2D_load when calling > glCompressTexSubImage2D. This is called only when the texture storage > object is used. This resulted in the texture rendering as black. Note > that the texture was loaded from a IVE file created with an earlier version > of OSG. > > After some investigation, I suspected that a possible cause was that the > texture included mipmaps down to 2x2 and 1x1 in size. The S3TC compression > being used has a block size of 4 so cannot be used for these small mipmap > levels. Modifying numMipmapLevels by subtracting 2 if the image is > compressed and using texture storage corrected the problem. However this > is likely not the best solution. > > My limited knowledge of OpenGL and this error suggests that this may be > highly dependent on the OpenGL implementation. I had several other > compressed textures larger than 32x32 with mipmaps down to 2x2 and 1x1 that > worked fine without this change. The OpenGL documentation (see > EXT_texture_compression_s3tc among others) however states that if the width > or height are not multiples of 4 then the result is an INVALID_OPERATION. > This can go unnoticed when not using a texture storage object. But with > the texture storage object, the error was generated when loading the full > texture (i.e. level 0). > > If my understanding is correct, others may have had similar issues with > compressed textures with mipmaps. They have worked around the issue by > disabling mipmaps for compressed textures in ReaderWriterDDS for example. > If the above holds true, then it may point to the underlying problem. > > Windows 7 64-bit, nVidia Driver 352.86, OSG 3.4.0 > > Scott > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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