In pbr.wgsl screen_space_dither goes out of scope if TONEMAP_IN_SHADER is not defined

[Ababwa]

Present in the latest version, which is 38a08d9 as of this writing.

In pbr.wgsl, a reference to screen_space_dither is made conditionally on #ifdef DEBAND_DITHER (line 113), but screen_space_dither is brought into scope in pbr_functions.wgsl, by importing bevy_core_pipeline::tonemapping conditionally on #ifdef TONEMAP_IN_SHADER (line 4).

If TONEMAP_IN_SHADER is not defined, but DEBAND_DITHER is, then the reference to screen_space_dither is present, but not defined, and the shader creation fails with this error:

ERROR bevy_render::render_resource::pipeline_cache: failed to create shader module: Validation Error

Caused by:
    In Device::create_shader_module

Shader '' parsing error: no definition in scope for identifier: 'screen_space_dither'
    ┌─ wgsl:830:34
    │
830 │     return vec4<f32>(color.rgb + screen_space_dither(pos.xy), color.a);
    │                                  ^^^^^^^^^^^^^^^^^^^ unknown identifier


    no definition in scope for identifier: 'screen_space_dither'

Either the reference to screen_space_dither in pbr.wgsl should be conditional on #ifdef TONEMAP_IN_SHADER, or the importing of bevy_core_pipeline::tonemapping in pbr_functions.wgsl should be conditional on (#ifdef TONEMAP_IN_SHADER OR #ifdef DEBAND_DITHER). I do not know if such a preprocessor operator exists to be able to do something like: #ifdef TONEMAP_IN_SHADER || DEBAND_DITHER, but such a change would seem to me to be the most correct fix for this issue.

I'm new to this interface and do not know how to add labels. My suggested labels are:
A-Rendering
C-Code-Quality

[Ababwa]

The error shown actually comes from a reference to screen_space_dither in pbr_functions.wgsl on line 275. This reference is also conditional on #ifdef DEBAND_DITHER, and has the same issue as the reference in pbr.wgsl.

[Ababwa]

The dither function in pbr_functions.wgsl (line 274), which contains a reference to screen_space_dither is never actually called anywhere. This function could be deleted. This may be a separate issue.