ADD(2)								System Calls Manual							    ADD(2)

NAME

       add,  sub,  mul, div, raddp, rsubp, rmul, rdiv, rshift, inset, rcanon, eqpt, eqrect, ptinrect, rectinrect, rectXrect, rectclip, Dx, Dy, Pt,
       Rect, Rpt - arithmetic on points and rectangles

SYNOPSIS

       #include <u.h>
       #include <libc.h>
       #include <libg.h>

       Point	   add(Point p, Point q)

       Point	   sub(Point p, Point q)

       Point	   mul(Point p, int a)

       Point	   div(Point p, int a)

       Rectangle   raddp(Rectangle r, Point p)

       Rectangle   rsubp(Rectangle r, Point p)

       Rectangle   rmul(Rectangle r, int a)

       Rectangle   rdiv(Rectangle r, int a)

       Rectangle   rshift(Rectangle r, int a)

       Rectangle   inset(Rectangle r, int n)

       Rectangle   rcanon(Rectangle r)

       int	   eqpt(Point p, Point q)

       int	   eqrect(Rectangle r, Rectangle s)

       int	   ptinrect(Point p, Rectangle r)

       int	   rectinrect(Rectangle r, Rectangle s)

       int	   rectXrect(Rectangle r, Rectangle s)

       int	   rectclip(Rectangle *rp, Rectangle b)

       int	   Dx(Rectangle r)

       int	   Dy(Rectangle r)

       Point	   Pt(int x, int y)

       Rectangle   Rect(int x0, int y0, int x1, int y1)

       Rectangle   Rpt(Point p, Point q)

DESCRIPTION

       The functions Pt, Rect and Rpt construct geometrical data types from their components.  These are implemented as macros.

       Add returns the Point sum of its arguments: Pt(p.x+q.x, p.y+q.y).  Sub returns the Point difference of its arguments: Pt(p.x-q.x, p.y-q.y).
       Mul returns the Point Pt(p.x*a, p.y*a).	Div returns the Point Pt(p.x/a, p.y/a).

       Raddp  returns  the  Rectangle  Rect(add(r.min,	p),  add(r.max,  p)); rsubp returns the Rectangle Rpt(sub(r.min, p), sub(r.max, p)).  Rmul
       returns the Rectangle Rpt(mul(r.min,a), mul(r.max,a)); Rdiv returns the Rectangle Rpt(div(r.min,a), div(r.max,a)).

       Rshift returns the rectangle r with all coordinates either left-shifted or right-shifted by a, depending on whether a is positive or  nega-
       tive, respectively.

       Inset returns the Rectangle Rect(r.min.x+n, r.min.y+n, r.max.x-n, r.max.y-n).

       Rcanon returns a rectangle with the same extent as r, canonicalized so that min.x <= max.x, and min.y <= max.y.

       Eqpt compares its argument Points and returns 0 if unequal, 1 if equal.	Eqrect does the same for its argument Rectangles.

       Ptinrect returns 1 if p is a point within r, and 0 otherwise.

       Rectinrect returns 1 if all the pixels in r are also in s, and 0 otherwise.

       RectXrect returns 1 if r and s share any point, and 0 otherwise.

       Rectclip  clips	in place the Rectangle pointed to by rp so that it is completely contained within b.  The return value is 1 if any part of
       *rp is within b.  Otherwise, the return value is 0 and *rp is unchanged.

       The functions Dx and Dy give the width (x) and height (y) of a Rectangle.  They are implemented as macros.

SOURCE

       /sys/src/libg

SEE ALSO

       graphics(2)

																	    ADD(2)