extract_half_res_gbuffer_view_normal_rgba8.hlsl

#include "inc/frame_constants.hlsl"
#include "inc/pack_unpack.hlsl"

[[vk::binding(0)]] Texture2D<float4> input_tex;
[[vk::binding(1)]] RWTexture2D<float4> output_tex;
[[vk::binding(2)]] cbuffer _ {
    float4 input_tex_size;
    float4 output_tex_size;
};

float3 normal_ws_at_px(int2 px) {
    return unpack_normal_11_10_11_no_normalize(input_tex[px].y);
}

[numthreads(8, 8, 1)]
void main(in int2 px : SV_DispatchThreadID) {
    const int2 src_px = px * 2 + HALFRES_SUBSAMPLE_OFFSET;

    float3 normal_ws = 1;

    // wired
    {
        const int k = 1;

        float3 avg_normal = 0;
        {for (int y = -k; y <= k + 1; ++y) {
            for (int x = -k; x <= k + 1; ++x) {
                avg_normal += normal_ws_at_px(px * 2 + int2(x, y));
            }
        }}
        avg_normal = normalize(avg_normal);

        float lowest_dot = 10;
        {for (int y = -k + 1; y <= k; ++y) {
            for (int x = -k + 1; x <= k; ++x) {
                float3 normal = normal_ws_at_px(px * 2 + int2(x, y));
                float d = dot(normal, avg_normal);
                if (d < lowest_dot) {
                    lowest_dot = d;
                    normal_ws = normal;
                }
            }
        }}
    }
    
    // tired; TODO: the "wired" version upsets specular, which assumes
    // that normals match up with hi-res ones at hi px locations
    normal_ws = normal_ws_at_px(src_px);

    float3 normal_vs = normalize(mul(frame_constants.view_constants.world_to_view, float4(normal_ws, 0)).xyz);
	output_tex[px] = float4(normal_vs, 1);
}