WebGPU: useExactSrgbConversions is broken

julien-moreau · June 28, 2026, 12:59pm

Hey!

I noticed a problem recently using the WebGPU engine. When enabling the useExactSrgbConversions parameter after engine creation or by using engine creation options generates tons of warnings and nothing is renderered.

Here is the repro playground: https://playground.babylonjs.com/#XDNVAY#41

Thanks a lot

RaananW · June 29, 2026, 9:54am

This should fix it:

github.com/BabylonJS/Babylon.js

Fix WGSL exact sRGB conversions failing on WebGPU (#18628)

master ← raananw-cautious-garbanzo

opened 09:53AM - 29 Jun 26 UTC

RaananW

+2 -2

## Problem When `engine.useExactSrgbConversions = true` is set on WebGPU, shade…rs fail to compile and nothing renders (blank canvas). Reproduced via https://playground.babylonjs.com/#XDNVAY#41: ``` Error while parsing WGSL: unresolved call target 'lessThanEqual' return mix(remainingSection, nearZeroSection, lessThanEqual(color, vec3f(0.04045))); ``` ## Cause The vec3 exact sRGB↔linear conversion helpers in `helperFunctions.fx` (WGSL) used GLSL's `lessThanEqual()`, which does not exist in WGSL. The scalar variants already correctly used `select()`. ## Fix Replaced `mix(..., lessThanEqual(...))` with `select(..., color <= ...)`. Arg order is preserved since `mix(a,b,cond)` and `select(a,b,cond)` both return `b` where the condition is true, and `vec3f <= vec3f` yields the `vec3<bool>` that `select` accepts per-component. Only the WebGPU exact-sRGB path was affected; default conversions and WebGL2 were unaffected. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

cc @Evgeni_Popov

julien-moreau · June 29, 2026, 11:35am

So fast thanks a lot I’ll let you know once I apply the new Babylon.js version

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WebGPU: useExactSrgbConversions is broken

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