Hi Robert, It's been a while, eh?
Well, here are submissions about handling of S3TC-DXTC (.dds) images. All changes are related, but they come in multiple commits. If I could easily base my work on a specific revision for "Image.cpp" (few changes), the recent changes in "ReaderWriterDDS.cpp" are based on my previous submissions. To avoid the pain of searching old submissions in the mailing list, I re-organized everything here. This is why you'll find 3 (numbered) versions of the RW, to separate changes in multiple commits. Just focus on this submission and forget my previous ones about DDS! :) Base revision is master b5fa42c203 / trunk r13348. Attached are the modified source files, a simple test program (which creates test images, or read+rewrites images through DDS ReaderWriter), and DDS files used & produced during this test. 1. Image.cpp Failure to perform a vertical flip on S3TC-DXTC now simply leaves the original image instead of corrupting it. Image.cpp was sometimes performing a "normal" (= for uncompressed images) vertical flip on S3TC-DXTC images, producing weird results. Actually, code was trying a "DXTC vertical flip" and relied on the result to call a "normal vertical flip". But when the "DXTC v-flip" encounters an error, this is is not necessarily because the image is not S3TC (ex: unhandled image dimensions)! So now the code simply does "if dxtc, then flip_dxtc; else flip_normal;". 2. ReaderWriterDDS-1.cpp Added some support of non-modulus-4 dimensions in S3TC-DXTC images (previous implementation seem just not to handle these properly). - Added missing packing value on S3TC images. Images are coded with 4x4 blocs, whatever the image size. So there is an horizontal packing of 4 pixels (2 bytes in DXT1, 4 bytes in DXT2-5). - Added crash guard against writing corrupted S3TC images. Notes: - What is missing is a support of "lines packing" in osg::Image (see code comments). - S3TC-DXTC vertical flipping crashes (access violation) with some unusual dimensions (see code). I could not implement missing cases, so I added guards to avoid crashing. 3. ReaderWriterDDS-2.cpp Added vertical flipping to the writer depending on the Image::getOrigin() value (= flip the image when Image::BOTTOM_LEFT). Most of the time this will not change DDS writing (= no v-flip), as it seems images are rarely "BOTTOM_LEFT". To skip this behaviour, the "ddsNoAutoFlipWrite" option was added. I also moved a few lines of code about "dds_flip" option, and made options reading more like in other ReaderWriters. 4. ReaderWriterDDS-3.cpp Added ".dds" file deletion on writing failure. Cheers, Sukender
DDSTest.7z
Description: application/7z-compressed
DDSTest source images and results.7z
Description: application/7z-compressed
DDS - Improved handling of S3TC-DXTC.7z
Description: application/7z-compressed
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