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#include <u.h>
#include <libc.h>
#include <draw.h>
#include <event.h>
#include <keyboard.h>
typedef struct Point2 Point2;
typedef struct Triangle Triangle;
typedef struct Circle Circle;
typedef struct Object Object;
struct Point2
{
double x, y, w;
};
struct Triangle
{
Point2 p0, p1, p2;
};
struct Circle
{
Point2 c;
double r;
};
struct Object
{
Triangle t;
Circle c;
};
enum {
Cbg,
Ctri,
Ccir,
NCOLOR
};
Image *pal[NCOLOR];
Object *tris;
ulong ntri;
Point2 pts[3];
int npt;
Point2
Pt2(double x, double y, double w)
{
return (Point2){x,y,w};
}
Point2
addpt2(Point2 p, Point2 q)
{
return (Point2){p.x+q.x,p.y+q.y,p.w+q.w};
}
Point2
subpt2(Point2 p, Point2 q)
{
return (Point2){p.x-q.x,p.y-q.y,p.w-q.w};
}
Point2
mulpt2(Point2 p, double s)
{
return (Point2){p.x*s,p.y*s,p.w*s};
}
Point2
divpt2(Point2 p, double s)
{
return (Point2){p.x/s,p.y/s,p.w/s};
}
double
veclen(Point2 p)
{
return sqrt(p.x*p.x + p.y*p.y);
};
Point2
crossvec(Point2 p, Point2 q)
{
return (Point2){
p.y*q.w - p.w*q.y,
p.w*q.x - p.x*q.w,
p.x*q.y - p.y*q.x
};
}
void
addobj(Triangle t, Circle c)
{
tris = realloc(tris, ++ntri*sizeof(Object));
tris[ntri-1].t = t;
tris[ntri-1].c = c;
}
double
triperi(Triangle t)
{
return veclen(subpt2(t.p0, t.p1))
+ veclen(subpt2(t.p1, t.p2))
+ veclen(subpt2(t.p2, t.p0));
};
double
triarea(Triangle t)
{
Point2 p;
double r;
p = crossvec(t.p0, t.p1);
p = addpt2(p, crossvec(t.p1, t.p2));
p = addpt2(p, crossvec(t.p2, t.p0));
r = sqrt(p.x*p.x + p.y*p.y + p.w*p.w);
return r/2;
}
Point
toscreen(Point2 p)
{
return addpt(screen->r.min, Pt(p.x,p.y));
}
Point2
fromscreen(Point p)
{
p = subpt(p, screen->r.min);
return (Point2){p.x,p.y,0};
}
void
triangle(Triangle t)
{
Point p[4];
p[0] = toscreen(t.p0);
p[1] = toscreen(t.p1);
p[2] = toscreen(t.p2);
p[3] = p[0];
poly(screen, p, nelem(p), Endsquare, Endsquare, 0, pal[Ctri], ZP);
}
void
circle(Circle c)
{
ellipse(screen, toscreen(c.c), c.r, c.r, 0, pal[Ccir], ZP);
}
void
initpalette(void)
{
pal[Cbg] = allocimage(display, Rect(0,0,1,1), screen->chan, 1, 0x000000ff);
pal[Ctri] = allocimage(display, Rect(0,0,1,1), screen->chan, 1, 0x00ff00ff);
pal[Ccir] = allocimage(display, Rect(0,0,1,1), screen->chan, 1, 0xff0000ff);
}
void
redraw(void)
{
int i;
draw(screen, screen->r, pal[Cbg], nil, ZP);
for(i = 0; i < ntri; i++){
triangle(tris[i].t);
circle(tris[i].c);
}
for(i = 0; i < npt; i++)
fillellipse(screen, toscreen(pts[i]), 2, 2, pal[Ctri], ZP);
flushimage(display, 1);
}
void
usage(void)
{
fprint(2, "usage: %s\n", argv0);
exits("usage");
}
void
main(int argc, char *argv[])
{
Event e;
Triangle t;
Circle c;
ARGBEGIN{
default: usage();
}ARGEND;
if(argc > 0)
usage();
if(initdraw(nil, nil, nil) < 0)
sysfatal("initdraw: %r");
initpalette();
einit(Emouse|Ekeyboard);
redraw();
for(;;)
switch(event(&e)){
case Emouse:
if((e.mouse.buttons&1) != 0){
pts[npt++] = fromscreen(e.mouse.xy);
if(npt >= nelem(pts)){
t.p0 = pts[0];
t.p1 = pts[1];
t.p2 = pts[2];
c.c = divpt2(addpt2(addpt2(mulpt2(t.p0, veclen(subpt2(t.p1, t.p2))),
mulpt2(t.p1, veclen(subpt2(t.p2, t.p0)))),
mulpt2(t.p2, veclen(subpt2(t.p0, t.p1)))),
triperi(t));
c.r = 2*triarea(t)/triperi(t);
addobj(t, c);
npt = 0;
}
redraw();
}
break;
case Ekeyboard:
switch(e.kbdc){
case 'q':
case Kdel:
exits(0);
}
break;
}
}
void
eresized(int)
{
if(getwindow(display, Refnone) < 0)
sysfatal("resize failed");
redraw();
}
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