Custom Render Phase Example

[IceSentry]

Objective

• Making a custom render phase is not very documented and you need to jump around deep in the bevy internals to understand what is going on.

Solution

• Add an example that shows a self-contained custom render phase and draw command

Note

There's some overlap with the shader_instancing and post_processing examples but this one is intended to really document the full pipeline while the other ones are more about a specific part of it. It might also be worth it to remove some redundant comments in the post_processing example and point to this one instead.

It will also be useful to have everything in one place for anyone that wants to work on reducing the boilerplate.

[MiniaczQ]

this is done in other examples too, but why are we using println instead of tracing's info?

[IceSentry]

This is a very work in progress PR and this was just used for debugging. It will definitely not be in the final PR.

[MiniaczQ]

why does one require as_mut().unwrap() and the other not?

[IceSentry]

The fragment shader is optional but the vertex shader is required. I don't remember what happens if you don't provide a fragment shader but it isn't required

[IceSentry]

The specialized_mesh_pipeline and custom_phase_item cover most of the important bits of this example. I might revisit this in the future but I'll do that in a new PR if I ever get to it.