#include <metal_stdlib>

using namespace metal;

constant float4 verts[] =

{

    float4(-1.0, 1.0, 0.0, 0.0),

    float4( 1.0, 1.0, 1.0, 0.0),

    float4(-1.0,-1.0, 0.0, 1.0),

    float4( 1.0,-1.0, 1.0, 1.0),

};

struct Varyings

{

    float4 position [[position]];

    float2 uv;

};

vertex Varyings quad_vertex_main(uint vid [[vertex_id]])

{

    Varyings out;

    out.position = float4(verts[vid].xy, 0.0, 1.0);

    out.uv = verts[vid].zw;

    return out;

}

fragment float4 quad_fragment_main(Varyings input [[stage_in]])

{

    return float4(input.uv, 0.0, 1.0);

}

constexpr sampler s(coord::normalized, address::repeat, filter::nearest);

fragment float4 textured_quad_fragment(Varyings input [[stage_in]],

                                       texture2d<float> tex [[texture(0)]])

{

    return tex.sample(s, input.uv);

}

fragment float4 visualize_depth_fragment(Varyings input [[stage_in]],

                                         depth2d<float> depth_texture [[texture(0)]])

{

    float4 d = depth_texture.sample(s, input.uv);

    return float4(d.xxx, 1.0);

}