move wgsl color operations from bevy_pbr to bevy_render

[arcashka]

Objective

bevy_pbr/utils.wgsl shader file contains mathematical constants and color conversion functions. Both of those should be accessible without enabling bevy_pbr feature. For example, tonemapping can be done in non pbr scenario, and it uses color conversion functions.

Fixes #13207

Solution

• Move mathematical constants (such as PI, E) from bevy_pbr/src/render/utils.wgsl into bevy_render/src/maths.wgsl
• Move color conversion functions from bevy_pbr/src/render/utils.wgsl into new file bevy_render/src/color_operations.wgsl

Testing

Ran multiple examples, checked they are working:

• tonemapping
• color_grading
• 3d_scene
• animated_material
• deferred_rendering
• 3d_shapes
• fog
• irradiance_volumes
• meshlet
• parallax_mapping
• pbr
• reflection_probes
• shadow_biases
• 2d_gizmos
• light_gizmos

---

Changelog

• Moved mathematical constants (such as PI, E) from bevy_pbr/src/render/utils.wgsl into bevy_render/src/maths.wgsl
• Moved color conversion functions from bevy_pbr/src/render/utils.wgsl into new file bevy_render/src/color_operations.wgsl

Migration Guide

In user's shader code replace usage of mathematical constants from bevy_pbr::utils to the usage of the same constants from bevy_render::maths.

[github-actions]

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[alice-i-cecile]

I agree with this reorganization: these aren't PBR specific.

[tychedelia]

Improved organization. LGTM.

[NthTensor]

This may help a bit when the rendering crates get reorganized.