CompressedImageSaver improvements by JMS55 · Pull Request #23567 · bevyengine/bevy

JMS55 · 2026-03-29T02:15:56Z

Objective

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Closes #14671.

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beicause · 2026-04-01T12:35:10Z

FYI I'm working on a basisu asset processor in beicause/bevy_basisu_loader#33

…ed-image-saver2

cwfitzgerald · 2026-04-12T16:14:55Z

+            return Err(CompressedImageSaverError::UninitializedImage);
+        };
+
+        if image.texture_descriptor.mip_level_count != 1 {


Note ctt can deal with any source amount of mips

cwfitzgerald · 2026-04-12T16:15:38Z

+                    stride: image.width() * bytes_per_pixel,
+                    format: input_format,
+                    color_space,
+                    alpha: ctt::AlphaMode::Straight, // TODO: User-configurable?


Yeah this should be user configurable.

cwfitzgerald · 2026-04-12T16:16:13Z

+            container: ctt::Container::Ktx2,
+            quality: ctt::Quality::default(),
+            output_color_space: None,
+            output_alpha: None,


The correct default here is Some(premultiplied), though should be user configurable

andriyDev

Overall LGTM. We're just calling another lib!

I haven't tested this locally, but the code looks fine (barring one complaint).

andriyDev · 2026-04-12T17:56:29Z

+        })
+    }
+
+    #[cfg(feature = "compressed_image_saver_universal")]


I am really not a fan of this. Saying we just straight up can't compile either case if both features are enabled kinda sucks.

WDYT about just having two CompressedImageSavers? CompressedImageSaverCtt and CompressedImageSaverUniversal? Then just pick one in the plugin? This way if users want to use the old compression, they can. You could also have a wrapper CompressedImageSaver for compatibility (which internally holds one of the backends), so that we keep old meta files working.

I am personally not a fan of mutually exclusive feature flags, since it means I can't just test with --all-features.

Generally the idea was that you'd always be using CompressedImageSaver (same meta files), and then depending on what platform you want to target, you'd enable different backends.

I think you can use feature gate within a custom asset processor instead of asset savers, instead of using LoadTransformAndSave.

cwfitzgerald · 2026-04-12T21:53:30Z

+///
+/// # ASTC override
+///
+/// Set the `BEVY_COMPRESSED_IMAGE_SAVER_ASTC` environment variable to compress into ASTC


I think the default should be based on the target. Like android and ios should default to ASTC and other platforms default to BCn.

I was thinking about this, but it would be pretty standard to compile for one platform on another, e.g. in CI, right?

Where does this code run? If you're cross compiling you should know the target you're cross compiling to.

cwfitzgerald · 2026-04-12T21:54:12Z

+/// increases GPU cache hits, improving rendering performance. Input images must have a
+/// `mip_level_count` of 1 (i.e., no pre-existing mip chain); the compressor will produce


I think this isn't true unless you force it? ctt will handle this

I need to generate the Surfaces in the correct order from Bevy's data, which I didn't feel like figuring out...

JMS55 added 2 commits March 28, 2026 22:15

WIP

f28892c

add todo

18cfdbb

JMS55 added the A-Assets Load files from disk to use for things like images, models, and sounds label Mar 29, 2026

github-project-automation bot added this to Assets Mar 29, 2026

github-project-automation bot moved this to Needs SME Triage in Assets Mar 29, 2026

JMS55 added 7 commits March 28, 2026 22:57

WIP

ef98abd

Disable selector RDO for linear, based on tune_for_normal_maps

ad31db5

WIP

a0d8313

Misc

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WIP

bd2ed87

Assert

fa171ae

WIP

c2454e1

alice-i-cecile added C-Usability A targeted quality-of-life change that makes Bevy easier to use S-Waiting-on-Author The author needs to make changes or address concerns before this can be merged labels Mar 29, 2026

Merge commit '842fa5c4559303edbd1774013bc0f3d0dd529799' into compress…

73d0687

…ed-image-saver2

beicause mentioned this pull request Apr 8, 2026

Replace basis-universal-rs with basisu_c_sys to improve basis universal support #23672

Open

JMS55 added 7 commits April 12, 2026 09:47

Merge commit '6dc30ca38789a1023df17649198b006e1df9cf5c' into compress…

108518d

…ed-image-saver2

WIP

542d427

Add TODO

a027777

Misc

f1346ba

Docs

48f9c44

Fix docs

5b90771

ASTC support

f92fb42

cwfitzgerald reviewed Apr 12, 2026

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JMS55 added 2 commits April 12, 2026 12:31

Docs

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andriyDev reviewed Apr 12, 2026

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cwfitzgerald reviewed Apr 12, 2026

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Comment thread _release-content/migration-guides/compressed_image_saver.md Outdated

Comment thread crates/bevy_image/src/compressed_image_saver.rs Outdated

Comment thread crates/bevy_image/src/compressed_image_saver.rs

Doc tweaks

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Typo

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cwfitzgerald reviewed Apr 12, 2026

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JMS55 added 2 commits April 12, 2026 18:12

Use BC6H for rgba16float

5f0f2b2

Zstd supercompression

6e1255c

		/// increases GPU cache hits, improving rendering performance. Input images must have a
		/// `mip_level_count` of 1 (i.e., no pre-existing mip chain); the compressor will produce

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JMS55 commented Mar 29, 2026

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beicause commented Apr 1, 2026

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cwfitzgerald Apr 12, 2026 •

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