Add support for BC7 texture compression

[Pesegato]

BC7 hardware compression is part of DirectX11

On the zip file there is a PNG and its BC7 equivalent.

16.zip

[stephengold]

Thanks for opening an issue.

[tonihele]

I actually started working on this. Also the few older formats that jME is missing (in DDS). I guess they come with the same effort. This is a bit early statement as I basically just added code to recognize them but not actually render. And hopefully my skills are sufficient for the latter.

So not yet confident enough to set the assignee on the issue... but just to let you guys know.

[stephengold]

There was discussion at the Forum/Hub: https://hub.jmonkeyengine.org/t/next-release-of-the-engine/44988/13

I'm still unclear whether encoding is a requirement or not. Most of the BC7 projects I've found on GitHub seem oriented toward encoding, not decoding, but there's https://github.com/richgel999/bc7enc_rdo that apparently does both.

Where can I obtain free 3-D models that use BC7?

[Pesegato]

Encoding is for creating or converting textures, and is beyond the scope of JME. For example, I use Compressonator to convert PNG into ready to use BC7 Textures.

[stephengold]

I'm still unclear on the motivation. If you have the texture as a PNG, why not use that?

[tonihele]

I think that this is just an example that doesnt really represent a real world use case. And the PNG is provided for comparison. So the implementer can verify the results.

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On Thu, 14 Oct 2021, 21:46 Stephen Gold, ***@***.***> wrote: I'm still unclear on the motivation. If you have the texture as a PNG, why not use that? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#1619 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB7VJPQRPZWQRFJ7AHMLMPTUG4QQPANCNFSM5F4ZDGSQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[stephengold]

OK, so what is the use case?

[tonihele]

The BC7 is the latest I suppose. Using these GPU compressed formats save sampling bandwidth, memory usage and provide faster texture loads. That is the general idea of these. Optimizing. jME supports some of the older formats but lacks support for all the BCx formats. Ill try to implement support for all those. It is just matter of recognising them and defining them. Should be quite simple... no encoding/decoding code needed.

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On Thu, 14 Oct 2021, 22:48 Stephen Gold, ***@***.***> wrote: OK, so what is the use case? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#1619 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB7VJPSJMASYXL5V4KQKQBLUG4X2RANCNFSM5F4ZDGSQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[Pesegato]

The BC7 is like the DXT5: texture are compressed in RAM at 1/4 of their size, saving memory and bandwidth. The improvement of BC7 is the quality of the compressed texture: while DXT5 came with noticeable artefacts and image degradation (these are lossy compressions), BC7 instead provide a almost-lossless conversion and minimal image degradation.
It requires a compatible hardware (DirectX11/Opengl 4.x) but by now most video card support that standard.

[Ali-RS]

I converted a jpg texture (4096x4096) with size 1.2MB to DDS with bc7 compression and the output file size became 16MB (and with dxt1 it became 8MB). I know DDS files are optimized for GPU memory but I am curious why the file size is so huge in comparison to JPG, PNG, or WebP?

Also, is bc7 compressions supported on Android devices?

[MeFisto94]

I converted a jpg texture (4096x4096) with size 1.2MB to DDS with bc7 compression and the output file size became 16 MB. I know DDS files are optimized for GPU memory but I am curious why the file size is so huge in comparison to JPG, PNG, or WebP?

Also, are DDS compressions supported on Android devices?

Because the DDS files contain mip-maps at different resolutions. Also keep in mind that non-DDS images will be put through the AWTLoader and then transferred as raw bitmap, so w * h * Bpp, which would already be 16 MB for 8 bit images, but 64 MiB for RGBA8, excluding mip-maps.

For the compression on Android, you probably need to check the openGL ES spec, but there are a lot of different compressions, maybe some especially made for mobile, but encoding them is typically the problem together with patents and stuff

[tonihele]

For the compression on Android, you probably need to check the openGL ES spec, but there are a lot of different compressions, maybe some especially made for mobile, but encoding them is typically the problem together with patents and stuff

On mobile we have currently ETC and with this issue I'm going to implement the newer ASTC, along with the BCxs.

I already got it (somewhat) working, this is the DDS, not the PNG ! :)