On 17/04/2018 15:33, Иван Комиссаров wrote:
At the point i wrote the plugin, my usecase was simple - to convert
plain QImages to and from DDS icons (used in starcraft2, which uses
quite a few formats DDS can handle).
But yes, i forgot floating point textures.
Compressed textures (DXTN/ATI2) are just compressed (a)rgb32, nobody
uses compressed jpeg, it is decompressed before usage (correct me if i'm
wrong, but videocards uses DDS because it's decompression algorithm can
be easily implemented in hardware)
DDS is just a container format. Peppe's point stands, QImage and friends
are the wrong vehicle for supporting this. They simply do not offer
enough degrees of freedom in the API to do so properly. And adding them
would be changing what QImage is designed for.
QImage is designed to represent a single image in one of a few supported
formats. Proper texture support needs to be able to address images by
mip level, array layer and cubemap face in any of the formats supported.
The compressions used by various formats supported within a DDS (or KTX)
file are designed so they can be decompressed on the fly for a small
block of pixels. These block compression algorithms do not offer such
on-disk savings as png/jpeg but are much easier to sample from in access
patterns typically required by fragment shaders.
I'm not saying a tool to convert to/from dds/some other format would not
be useful. Just that QImage is the wrong way to approach this due to the
above.
Sean
2018-04-17 14:28 GMT+03:00 Giuseppe D'Angelo <[email protected]
<mailto:[email protected]>>:
On 17/04/18 13:21, Иван Комиссаров wrote:
Ok, there's another problem with QImage - ARGB64 and friends...
This can be solved adding QImage::pixel64() or something like
that... or use QTexture with 64bit "pixel"
And a bunch of packed formats not currently supported, and floating
point channels, and compressed texture formats. I stand my point:
DDS files are not meant to be handled by QImage.
What is your use case exactly for wanting this support?
Cheers,
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<mailto:[email protected]> | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
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KDAB - The Qt, C++ and OpenGL Experts
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