Use BindGroupLayoutEntryBuilder in texture_binding_array example

[mgi388]

Objective

• I've been using the texture_binding_array example as a base to use multiple textures in meshes in my program
• I only realised once I was deep in render code that these helpers existed to create layouts
• I wish I knew the existed earlier because the alternative (filling in every struct field) is so much more verbose

Solution

• Use BindGroupLayoutEntries::with_indices to teach users that the helper exists
• Also fix typo which should be texture_2d.

Alternatives considered

• Just leave it as is to teach users about every single struct field
• However, leaving as is leaves users writing roughly 29 lines versus roughly 2 lines for 2 entries and I'd prefer the 2 line approach

Testing

Ran the example locally and compared before and after.

Before:

After:

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[mgi388]

@robtfm and @IceSentry hope I can ping you for a review. I see that you both worked on a) the example and b) the helpers.

[IceSentry]

I'm not sure if the comments with the full wgsl bind group code is necessary but it doesn't really hurt either so that's fine I guess.

[mgi388]

I'm not sure if the comments with the full wgsl bind group code is necessary but it doesn't really hurt either so that's fine I guess.

I'm impartial, I just left it in there because it was already there.

FWIW, as someone relatively unfamiliar with how these entries map to the WGSL bind group code, I will say I found it to be a nice clue to how they are actually mapped. E.g. the 1 index in Rust code means I should look for a @binding(1) in the WGSL code.

[IceSentry]

FWIW, as someone relatively unfamiliar with how these entries map to the WGSL bind group code, I will say I found it to be a nice clue to how they are actually mapped. E.g. the 1 index in Rust code means I should look for a @binding(1) in the WGSL code.

In that case it's worth leaving there. I tried to make that api to be relatively clear to what it maps to in wgsl, but I'm very biased since I'm the one that made it so it's understandable that it isn't as obvious to other people. Anyway, I also just want more people to use it because it makes writing that kind of code much easier.