$home/manuals/unix_v8/9/add

ADD(9.3)                                                              ADD(9.3)



NAME
       add,  sub,  mul,  div,  eqpt,  eqrect,  inset, muldiv, ptinrect, raddp,
       rsubp, rectXrect, rectclip - arithmetic on points and rectangles

SYNOPSIS
       #include <jerq.h>

       Point add(p, q) Point p, q;

       Point sub(p, q) Point p, q;

       Point mul(p, a) Point p; int a;

       Point div(p, a) Point p; int a;

       int eqpt(p, q) Point p, q;

       int eqrect(r, s) Rectangle r, s;

       Rectangle inset(r, n) Rectangle r; int n;

       int muldiv(a, b, c) int a, b, c;

       int ptinrect(p, r) Point p; Rectangle r;

       Rectangle raddp(r, p) Rectangle r; Point p;

       Rectangle rsubp(r, p) Rectangle r; Point p;

       int rectXrect(r, s) Rectangle r, s;

       int rectclip(rp, s) Rectangle *rp, s;

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

       Eqpt and eqrect return the equality of their arguments: 0 if unequal, 1
       if equal.  Two Points or Rectangles are equal  if  their  corresponding
       coordinates are equal.

       Inset  returns the Rectangle (r.origin.x+n, r.origin.y+n, r.corner.x-n,
       r.corner.y-n).  The following code creates a clear rectangle r  with  a
       2-dot wide border inside r:

              rectf(&display, r, F_OR);
              rectf(&display, inset(r, 2), F_CLR);

       Muldiv  is  a  macro that returns the 16-bit result (a*b)/c, with (a*b)
       calculated to 32 bits, so no precision is lost.  Muldiv  is  convenient
       for calculating transformations.

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

       Raddp returns the Rectangle (add(r.origin, p), add(r.corner, p)); rsubp
       returns the Rectangle (sub(r.origin, p), sub(r.corner, p)).

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

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

SEE ALSO
       types(9.5)



                                                                      ADD(9.3)