Question

There’s no way to do something like this, in C++ is there?

union {
    {
        Scalar x, y;
    }
    Scalar v[2];
};

Where x == v[0] and y == v[1]?

Answer 1

I’ve used something like this before. I’m not sure its 100% OK by the standard, but it seems to be OK with any compilers I’ve needed to use it on.

struct Vec2
{
  float x;
  float y;
  float& operator[](int i) { return *(&x+i); }
};

You can add bounds checking etc to operator[] if you want ( you probably should want) and you can provide a const version of operator[] too.

If you’re concerned about padding (and don’t want to add the appropriate platform specific bits to force the struct to be unpadded) then you can use:

struct Vec2
{
  float x;
  float y;
  float& operator[](int i) {
    assert(i>=0);
    assert(i<2);
    return (i==0)?x:y;
  }
  const float& operator[](int i) const {
    assert(i>=0);
    assert(i<2);
    return (i==0)?x:y;
  }
};