Hi Mikhail, I think you have mis-intrepted my suggestion that DTX1a and DTX1c have essential the same header and contents - I mean in that they are the same format in memory so we can't distinguish between the two.
One would not expect nvcompress to produce the same output for DXT1a and DTX1c and I didn't mean to imply that it or any other tool would. Instead I meant to infer that such a tool that generated a DTX1a image with transparent pixels could be identical to a DTX1c image with black pixels. Robert. On Thu, Apr 14, 2011 at 1:34 PM, Mikhail I. Izmestev <[email protected]> wrote: > 14.04.2011 16:16, Robert Osfield wrote: > >> The heart of the problem is that the DDS file format doesn't >> distiguish between the >> two varients of DXT1, there is an alpha bit in the DDS header that >> could be used, >> but 3rd party tools like nvdxt and nvcompress that write DDS files >> don't set this bit >> so both DTX1c with black encoded pixels and DTX1a are essentially >> identical >> in terms of header and content. > > Where from this information? > > $ nvdxt.exe -nomipmap -dxt1a -file test_dxt1.png -output test_dxt1a.dds > Version 8.30 > Reading test_dxt1.png [Processing] Writing .\test_dxt1a.dds > > $ nvdxt.exe -nomipmap -dxt1c -file test_dxt1.png -output test_dxt1c.dds > Version 8.30 > Reading test_dxt1.png [Processing] Writing .\test_dxt1c.dds > > $ md5sum.exe test_dxt1*.dds > ac1473f8822abbb2d6006de0021c6bc0 *test_dxt1a.dds > 249071d0b0974593b310656acea73e1d *test_dxt1c.dds > > Mikhail > _______________________________________________ > 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
