I'm NOT asking how to render voxels. I'm asking how should I put my voxel shader!

[CoderJo-Pro]

Here I'm making a voxel rendering pipeline, where it runs a voxel fragment shader, which uses DDA or octree, not meshes. So the attempts below might not be the best way to do it, please tell me when it's not.

I'm basically learning from documentation agents like zread.ai and deepwiki.com. The goal is to cast rays to the voxels and output PBR material, and get render result from bevy.

At the beginning, I created a node to compute depth and color before meshes. Hope this was correct:

render_app
    .add_systems(RenderStartup, init_voxel_pipeline)
    .add_render_graph_node::<ViewNodeRunner<VoxelNode>>(Core3d, VoxelLabel)
    .add_render_graph_edges(
        Core3d,
        (
            Node3d::StartMainPass,
            VoxelLabel,
            Node3d::MainOpaquePass,
        ),
    );

And with some ray casts calculated from View uniform, it worked. I then attempted to integrate the voxels directly to bevy's PBR. Switching to deferred rendering sounds like an obvious choice.

According to the doc agent, I should use several WGSL functions from bevy_pbr to make PbrInput into a G-Buffer texel. Hope this make sense to you:

struct VoxelDeferredOutput {
    @location(0) gbuffer: vec4<u32>,        // G-Buffer
    @location(1) lighting_pass_id: u32,     // lighting pass id
    @builtin(frag_depth) depth: f32,
}

@fragment
fn fragment(in: FullscreenVertexOutput) -> VoxelDeferredOutput {
    let voxel = cast_ray(in);

    var pbr = pbr_input_new();
    pbr.material.base_color = vec4(voxel.albedo, 1.0);
    // ...
    pbr.material.flags = 0u;  // not unlit
    pbr.N = normalize(voxel.world_normal);
    pbr.world_normal = pbr.N;
    pbr.frag_coord = in.position;
    pbr.flags = 0u;  // shadow receiver bit optional setting
    // ...

    let gbuffer = deferred_gbuffer_from_pbr_input(pbr);
    let ndc_depth = view_z_to_depth_ndc(voxel.view_z, view.clip_from_view);

    return VoxelDeferredOutput(
        gbuffer,
        1u,   // 1 = StandardMaterial's default lighting pass id
        ndc_depth,
    );
}

Actually, none of that matters. Because obviously wgpu is not happy about this. The uniforms are whether not exited, or conflicting with my own voxel shader's View uniform.

Of course it would... I imported the functions from bevy_pbr, and I have to bind their uniforms too. But God they are so many! I have to bind all of them, and I have to do it manually.

Hold on, the doc agent tells me there is MeshViewBindGroup.main_offset that I can pass in to render_pass.set_bind_group(). But it turns out that it's a new feature from the main branch (where those doc agents are based on).

So, my crate depends on bevy 0.18, there has to be some way to get these uniforms' indices. Ok, I admit that I have to do it manually, but how?