// include API declarations as needed
#include "gpuc/gpuc.h"

// include implementation in one translation unit
#include "gpuc/gpuc.inl"

» sh gpuc.c --help
usage:

  gpuc [options] <source>

options:

  --help           display this usage summary
  --ast            print AST to stdout
  --debug          print debug summary to stdout
  --test           run tests
  --glsl           translate GPUC to GLSL
  --hlsl           translate GPUC to HLSL
  --metal          translate GPUC to Metal
  --frag <file>    write output to <file>, or '-' for stdout
  --vert <file>    write output to <file>, or '-' for stdout

» sh gpuc.c sample.gpuc --vert - --frag - --metal

#include <metal_stdlib>
#include <simd/simd.h>

using namespace metal;

float4 sample(const texture2d<float> t, float2 uv) {
    constexpr sampler s(filter::nearest);
    return t.sample(s, uv);
}

float4 sample(const texture2d<float> t, float2 uv, const sampler s) {
    return t.sample(s, uv);
}

struct gpuc {

    // float4 sample(texture2d, float2);

    // float4 sample(texture2d, float2, sampler);

    struct Camera {
        float4x4 mvp;
        float4x4 mvn;
    };

    struct Vertex {
        float3 position [[attribute(0)]];
        float4 color [[attribute(1)]];
        float4 texcoords [[attribute(2)]];
    };

    struct Fragment {
        float4 position [[position]];
        float4 color;
        float4 texcoords;
    };

    struct Sample {
        float4 color;
    };

    constant const Camera& cam;

    const texture2d<float> color;

    const sampler samp;

    Fragment vert(const Vertex v) const {
        Fragment f;
        f.position = cam.mvp * float4(v.position, 1);
        f.color = v.color;
        f.texcoords = v.texcoords;
        return f;
    }

};

vertex gpuc::Fragment vert(
    constant const gpuc::Camera& cam [[buffer(0)]],
    texture2d
    color [[texture(
   0)]],
    sampler samp [[sampler(
   0)]],
    
   const gpuc::Vertex v [[stage_in]]
) {
    
   return gpuc{cam, color, samp}.
   vert(v);
}
#
   include 
   <metal_stdlib>
#
   include 
   <simd/simd.h>

using namespace metal;

float4 
   sample(
   const texture2d<
   float> t, float2 uv) {
    constexpr sampler 
   s(filter::nearest);
    
   return t.
   sample(s, uv);
}

float4 
   sample(
   const texture2d<
   float> t, float2 uv, 
   const sampler s) {
    
   return t.
   sample(s, uv);
}


   struct gpuc {

    
   // float4 sample(texture2d, float2);

    
   // float4 sample(texture2d, float2, sampler);

    
   struct Camera {
        float4x4 mvp;
        float4x4 mvn;
    };

    
   struct Vertex {
        float3 position;
        float4 color;
        float4 texcoords;
    };

    
   struct Fragment {
        float4 position [[position]];
        float4 color;
        float4 texcoords;
    };

    
   struct Sample {
        float4 color;
    };

    constant 
   const Camera& cam;

    
   const texture2d<
   float> color;

    
   const sampler samp;

    Sample 
   frag(
   const Fragment f) 
   const {
        Sample s;
        s.
   color = 
   sample(color, f.
   texcoords.
   st, samp);
        
   return s;
    }

};

fragment gpuc::Sample 
   frag(
    constant 
   const gpuc::Camera& cam [[buffer(
   0)]],
    texture2d
   
     color [[texture(
    0)]],
    sampler samp [[sampler(
    0)]],
    
    const gpuc::Fragment f [[stage_in]]
) {
    
    return gpuc{cam, color, samp}.
    frag(f);
}