Question

I want to create a struct which is like a CGPoint, but with 3 coordinates instead of 2.

I create it in the following way:

typedef struct {CGFloat x;CGFloat y;CGFloat z;} CG3Vector;

CG_INLINE CG3Vector CG3VectorMake(CGFloat x, CGFloat y, CGFloat z)
{
  CG3Vector p; p.x = x; p.y = y; p.z = z; return p;
}

It works fine. But I now want to improve this struct so that it has the constants like for CGPoint: CGPointZero

Also what is the way to introduce the limits for particular components of the struct, like it is for the CGSize, where components are never lower than 0?

Thanks.

Answer 1

You could create constants like this:

const CG3Vector CG3VectorZero = { 0, 0, 0 };

If you want limits, I suppose you can do some checking like this:

CG_INLINE CG3Vector CG3VectorMake(CGFloat x, CGFloat y, CGFloat z)
{
    // normalize the values
    x = fmod(x, 360);
    y = fmod(y, 360);
    z = fmod(z, 360);

    x = (x < 0) ? 360 + x : x;
    y = (y < 0) ? 360 + y : y;
    z = (z < 0) ? 360 + z : z;

    return (CG3Vector) { x, y, z };
}