ParticleTextureSheet defines the GL state particles are rendered under (it's basically an older and way more primitive version of RenderLayer for particles)

In ParticleManager.renderParticles, vanilla iterates over a final immutable list of layers, instead of using the Map<ParticleTextureSheet, Queue<Particle>>'s keyset (and skipping NO_RENDER)

It would be convenient for modders with custom particle render types (like Botania) if a mixin could be added to iterate over the keyset instead of the final immutable list. Such a mixin would be small and be the only fix that is needed, vanilla handles everything else already.

As for why this needs to be in FAPI:

• It's small
• All modders with custom particle GL state need it
• Multiple modders doing this same fix could be catastrophous (render particles multiple times)
• Adding to the final immutable list is dirty and inconvenient.

Fixing this issue is really just a matter of replacing the iterator in ParticleManager.renderParticles like this:

@Mixin(ParticleManager.class)
public class ParticleRenderFix {

    @Final
    @Shadow
    private Map<ParticleTextureSheet, Queue<Particle>> particles;

    @ModifyVariable(method="renderParticles", at=@At("STORE"), ordinal = 0)
    private Iterator<ParticleTextureSheet> fixParticleTextureSheets(Iterator<ParticleTextureSheet> i){
        return this.particles.keySet().stream().toList().iterator();
    }
}

But I agree this should really just be part of the FAPI

Feel free to PR it. :)

I can see the benefit of this. I would like to see RenderLayer abstracted just a little bit, perhaps with some kind of builder.

In your use case, are you using a custom RenderLayer or manipulating Gl state directly?

all particle render layers manipulate GL state directly (See implementations of ParticleTextureSheet in vanilla)

At the moment I do the same.