#include <metal_stdlib>

using namespace metal;

template<typename T, int N, int M>
inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
  return lhs * vec<T, N>(rhs);
}

template<typename T, int N, int M>
inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
  return vec<T, M>(lhs) * rhs;
}

struct S {
  /* 0x0000 */ packed_float3 v;
  /* 0x000c */ uint i;
};

float3 Bad(uint index, float3 rd) {
  float3 normal = float3(0.0f);
  normal[index] = -(sign(rd[index]));
  return normalize(normal);
}

void tint_symbol_inner(device S& io, uint idx) {
  io.v = Bad(io.i, io.v);
}

kernel void tint_symbol(uint idx [[thread_index_in_threadgroup]], device S& io [[buffer(0)]]) {
  tint_symbol_inner(io, idx);
  return;
}