ADD(2G) ADD(2G)
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)
Page 1 Plan 9 (printed 12/21/24)
ADD(2G) ADD(2G)
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 mac-
ros.
Add returns the Point sum of its arguments: Pt(p.x+q.x,
p.y+q.y). Sub returns the Point difference of its argu-
ments: 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 negative, 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, canon-
icalized 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 Rectan-
gles.
Ptinrect returns 1 if p is a point within r, and 0 other-
wise.
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 other-
wise.
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 (Δx) and height (Δy)
of a Rectangle. They are implemented as macros.
SEE ALSO
Page 2 Plan 9 (printed 12/21/24)
ADD(2G) ADD(2G)
graphics(2)
Page 3 Plan 9 (printed 12/21/24)