// G-buffer deferred render — albedo * shadow
// Reads feat_tex0 (rgba32uint, f16 geometric) and feat_tex1 (rgba32uint, u8 context).
// Unpacks albedo and shadow and outputs albedo * shadow.

@group(0) @binding(0) var feat_tex0: texture_2d<u32>;
@group(0) @binding(1) var feat_tex1: texture_2d<u32>;
@group(0) @binding(2) var<uniform> uniforms: GBufDeferredUniforms;

struct GBufDeferredUniforms {
    resolution: vec2f,
}

@vertex
fn vs_main(@builtin(vertex_index) vid: u32) -> @builtin(position) vec4f {
    let x = f32((vid & 1u) << 2u) - 1.0;
    let y = f32((vid & 2u) << 1u) - 1.0;
    return vec4f(x, y, 0.0, 1.0);
}

@fragment
fn fs_main(@builtin(position) pos: vec4f) -> @location(0) vec4f {
    let coord = vec2i(pos.xy);

    // feat_tex0 layout:
    //   [0] pack2x16float(albedo.r, albedo.g)
    //   [1] pack2x16float(albedo.b, normal.x)
    let t0 = textureLoad(feat_tex0, coord, 0);
    let rg  = unpack2x16float(t0.x);
    let bx  = unpack2x16float(t0.y);
    let albedo = vec3f(rg.x, rg.y, bx.x);

    // feat_tex1 layout:
    //   [2] pack4x8unorm(mip2.g, mip2.b, shadow, transp)
    let t1     = textureLoad(feat_tex1, coord, 0);
    let ctx2   = unpack4x8unorm(t1.z);
    let shadow = ctx2.z;  // shadow is the third byte

    return vec4f(albedo * shadow, 1.0);
}