Hi Christian, Does this mean there is a bug in the MS version of math.h and the floor function it provides?
Previously we haven't used cmath as some platforms didn't support it properly, I recall IRIX being a problem, but am not sure if it extends further than this. IRIX support has long been deprecated so won't be a constraint these days. So... using #include<cmath> could well be a viable solution, It does still concern me that the MS version of math.h is giving different results to cmath. Robert. On 9 January 2013 15:27, Christian Schulte <[email protected]> wrote: > Hi all, > > I have investigated a little deeper the problem... Indeed, on Windows > platform, the number of mipmaps returned by > osg::Image::computeNumberOfMipmapLevels( s, t, r ) is wrong, but it is > correct on Linux platforms for the same dds file... > Here is attached a little test program that explains why (it is more or less > a computeNumberOfMipmapLevels with s=t=1024 and r=1), and it is not linked > to OSG. Compile it on Windows 32 bits (works on Win7 and WinXP) (g++ > main.cpp -o main.exe) You will see the following result : > > logf(wf) = 6.93147182464599609375 > log(wd) = 6.93147180559945308431 > logf(2.0f) = 0.69314718246459960938 > log(2.0) = 0.69314718055994528623 > logf(wf)/logf(2.0f) = 10.00000000000000000000 > log(wd)/log(2.0) = 10.00000000000000000000 > floor(logf(wf)/logf(2.0f)) = 9.00000000000000000000 -> Here is the error, it > should be 10 too... > floor(log(wd)/log(2.0)) = 10.00000000000000000000 > floor(testf) = 10.00000000000000000000 > floor(testd) = 10.00000000000000000000 > > Replacing the include of math.h by cmath results in : > > logf(wf) = 6.93147182464599609375 > log(wd) = 6.93147180559945308431 > logf(2.0f) = 0.69314718246459960938 > log(2.0) = 0.69314718055994528623 > logf(wf)/logf(2.0f) = 10.00000000000000000000 > log(wd)/log(2.0) = 10.00000000000000000000 > floor(logf(wf)/logf(2.0f)) = 10.00000000000000000000 > floor(log(wd)/log(2.0)) = 10.00000000000000000000 > floor(testf) = 10.00000000000000000000 > floor(testd) = 10.00000000000000000000 > > Under Linux both solutions give the second results. > The problem is that osg/Math includes math.h and not cmath. I don't know > which would be the best solution : > > Replace math.h by cmath in include/osg/Math > Store the logf division (float testf = logf(wf)/logf(2.0f)) of > osg::Image::computeNumberOfMipmapLevels( s, t, r ) in a float before > computing the floor. > > Up to the list to give the answer... > > PS : this is also the solution to the discussion "osgPlugins : dds problem > on windows platform" I launched 07/03/2011 > > Cheers, > > Christian Schulte > > > > > Le 20/12/2012 15:15, Lukasz Izdebski a écrit : > > Hi, > i probably have solution for this problem, i have found a bug in dds plugin > ReaderWriterDDS.cpp > Line 633 > unsigned numMipmaps = osg::Image::computeNumberOfMipmapLevels( s, t, r ); > > when compute numMipmaps returns wrong number. this number is less then > number of mipmaps in dds file( ddsd.dwMipMapCount ) . This bug makes that > when dds mipmaps are loaded to opengl last mipmap (4x4) isn't loaded. and > with combination with LINEAR_MIPMAP_LINEAR make this bug. > > > the numMipmaps should be taken form ddsd.dwMipMapCount > > > in attachment i send a corrected version of file. > ... > > Thank you! > > Cheers, > Lukasz > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=51653#51653 > > > > > Attachments: > http://forum.openscenegraph.org//files/readerwriterdds_204.cpp > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
