code: func Vec3Sub(dest, v1, v2 Vec3) {
  	dest[0] = v1[0] - v2[0]
  	dest[1] = v1[1] - v2[1]
  	dest[2] = v1[2] - v2[2]
  }
docs: // Vec3Sub performs a vector subtraction. dest = v1 - v2.
  //
  //     dest  [out]  The result vector.
  //     v1    [in]   The base vector.
  //     v2    [in]   The vector to subtract from v1.