Point functions

Data Structures
struct	POINT
	2D Point struct More...

Typedefs
typedef struct POINT	POINT
	2D Point struct
typedef struct POINT	POINT32

Functions
INLINE POINT *	pt_set (POINT *pd, int x, int y)
	Initialize pd to (x, y)
INLINE POINT *	pt_add (POINT *pd, const POINT *pa, const POINT *pb)
	Point addition: pd = pa + pb.
INLINE POINT *	pt_sub (POINT *pd, const POINT *pa, const POINT *pb)
	Point subtraction: pd = pa - pb.
INLINE POINT *	pt_scale (POINT *pd, const POINT *pa, int c)
	Point scale: pd = c * pa.
INLINE POINT *	pt_add_eq (POINT *pd, const POINT *pb)
	Point increment: pd += pb.
INLINE POINT *	pt_sub_eq (POINT *pd, const POINT *pb)
	Point decrement: pd -= pb.
INLINE POINT *	pt_scale_eq (POINT *pd, int c)
	Point scale: pd *= c.
INLINE int	pt_cross (const POINT *pa, const POINT *pb)
	Point 'cross'-product: pa × pb.
INLINE int	pt_dot (const POINT *pa, const POINT *pb)
	Point 'dot'-product:pa · pb.
int	pt_in_rect (const POINT *pt, const struct RECT *rc)

Detailed Description

Function Documentation

pt_cross()

INLINE int pt_cross	(	const POINT *	pa,
		const POINT *	pb
	)

Point 'cross'-product: pa × pb.

Actually, there's no such thing as a 2D cross-product, but you could extend it to 3D and get the value of its z-component, which can be used for a test for parallelism.