From 11b5a9d404f0d53e3ba0306ea35cebe0dea534f4 Mon Sep 17 00:00:00 2001 From: rodri Date: Sun, 28 Jun 2020 16:50:26 +0000 Subject: new toy: ptintriangle --- mkfile | 1 + ptintriangle.c | 252 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 253 insertions(+) create mode 100644 ptintriangle.c diff --git a/mkfile b/mkfile index 9e967c6..90cd85a 100644 --- a/mkfile +++ b/mkfile @@ -12,6 +12,7 @@ TARG=\ imagelerp\ rframeviz\ ptinpoly\ + ptintriangle\ HFILES=\ libgeometry/geometry.h\ diff --git a/ptintriangle.c b/ptintriangle.c new file mode 100644 index 0000000..6313e8b --- /dev/null +++ b/ptintriangle.c @@ -0,0 +1,252 @@ +#include +#include +#include +#include +#include +#include +#include + +enum { + PCBg, + PCFg, + PCPoly, + PCPolydark, + PCAux, + NCOLORS +}; + +typedef struct Triangle Triangle; + +struct Triangle +{ + Point2 p0, p1, p2; +}; + +Rectangle UR = {0,0,1,1}; /* unit rectangle */ +RFrame worldrf; +Image *pal[NCOLORS]; +Triangle thetriangle; +Point2 thepoint; +int isinside; + +void resized(void); + +Point +toscreen(Point2 p) +{ + p = invrframexform(p, worldrf); + return Pt(p.x,p.y); +} + +Point2 +fromscreen(Point p) +{ + return rframexform(Pt2(p.x,p.y,1), worldrf); +} + +/* + * comparison of a point p with an edge [e0 e1] + * p to the right: + + * p to the left: - + * p on the edge: 0 + */ +static int +edgeptcmp(Point2 e0, Point2 e1, Point2 p) +{ + Point3 e0p, e01, r; + + p = subpt2(p, e0); + e1 = subpt2(e1, e0); + e0p = Vec3(p.x,p.y,0); + e01 = Vec3(e1.x,e1.y,0); + r = crossvec3(e0p, e01); + + /* clamp to avoid overflow */ + return fclamp(r.z, -1, 1); /* e0.x*e1.y - e0.y*e1.x */ +} + +int +ptintriangle(Point2 p, Triangle t) +{ + /* counter-clockwise check */ + return edgeptcmp(t.p0, t.p2, p) <= 0 && + edgeptcmp(t.p2, t.p1, p) <= 0 && + edgeptcmp(t.p1, t.p0, p) <= 0; +} + +Triangle +Trianpt(Point2 p0, Point2 p1, Point2 p2) +{ + return (Triangle){p0, p1, p2}; +}; + +void +triangle(Image *dst, Triangle t, int thick, Image *src, Point sp) +{ + Point pl[4]; + + pl[0] = toscreen(t.p0); + pl[1] = toscreen(t.p1); + pl[2] = toscreen(t.p2); + pl[3] = pl[0]; + + poly(dst, pl, nelem(pl), Endsquare, Endsquare, thick, src, sp); +} + +void +filltriangle(Image *dst, Triangle t, Image *src, Point sp) +{ + Point pl[3]; + + pl[0] = toscreen(t.p0); + pl[1] = toscreen(t.p1); + pl[2] = toscreen(t.p2); + + fillpoly(dst, pl, nelem(pl), 0, src, sp); +} + +void +initpalette(void) +{ + pal[PCBg] = allocimage(display, UR, screen->chan, 1, DWhite); + pal[PCFg] = allocimage(display, UR, screen->chan, 1, DBlack); + pal[PCPoly] = allocimage(display, UR, screen->chan, 1, DPalebluegreen); + pal[PCPolydark] = allocimage(display, UR, screen->chan, 1, DDarkblue); + pal[PCAux] = allocimage(display, UR, screen->chan, 1, DRed); +} + +void +drawbanner(void) +{ + static char *msgs[] = { + "THE POINT IS OUTSIDE", + "THE POINT IS INSIDE" + }, *s; + + s = msgs[isinside]; + string(screen, toscreen(Pt2(Dx(screen->r)/2 - strlen(s)/2*font->width,10,1)), pal[PCFg], ZP, font, s); +} + +void +redraw(void) +{ + lockdisplay(display); + draw(screen, screen->r, pal[PCBg], nil, ZP); + filltriangle(screen, thetriangle, pal[PCPoly], ZP); + triangle(screen, thetriangle, 1, pal[PCPolydark], ZP); + fillellipse(screen, toscreen(thetriangle.p0), 2, 2, pal[PCPolydark], ZP); + fillellipse(screen, toscreen(thetriangle.p1), 2, 2, pal[PCPolydark], ZP); + fillellipse(screen, toscreen(thetriangle.p2), 2, 2, pal[PCPolydark], ZP); + fillellipse(screen, toscreen(thepoint), 2, 2, pal[PCAux], ZP); + drawbanner(); + flushimage(display, 1); + unlockdisplay(display); +} + +void +rmb(Mousectl *mc) +{ + thepoint = fromscreen(mc->xy); + isinside = ptintriangle(thepoint, thetriangle); +} + +void +lmb(Mousectl *mc) +{ + USED(mc); +} + +void +mouse(Mousectl *mc) +{ + if((mc->buttons&1) != 0) + lmb(mc); + if((mc->buttons&4) != 0) + rmb(mc); +} + +void +key(Rune r) +{ + switch(r){ + case Kdel: + case 'q': + threadexitsall(nil); + } +} + +void +usage(void) +{ + fprint(2, "usage: %s\n", argv0); + exits("usage"); +} + +void +threadmain(int argc, char *argv[]) +{ + Mousectl *mc; + Keyboardctl *kc; + Rune r; + Point2 tmp; + + GEOMfmtinstall(); + ARGBEGIN{ + default: usage(); + }ARGEND; + if(argc > 0) + usage(); + + if(initdraw(nil, nil, nil) < 0) + sysfatal("initdraw: %r"); + if((mc = initmouse(nil, screen)) == nil) + sysfatal("initmouse: %r"); + if((kc = initkeyboard(nil)) == nil) + sysfatal("initkeyboard: %r"); + initpalette(); + + worldrf.p = Pt2(screen->r.min.x,screen->r.min.y,1); + worldrf.bx = Vec2(1,0); + worldrf.by = Vec2(0,1); + tmp = Pt2(Dx(screen->r)/2,Dy(screen->r)/2,1); + thetriangle = Trianpt(tmp, addpt2(tmp, Vec2(200,0)), addpt2(tmp, Vec2(0,-160))); + + display->locking = 1; + unlockdisplay(display); + redraw(); + + for(;;){ + enum { MOUSE, RESIZE, KEYBOARD }; + Alt a[] = { + {mc->c, &mc->Mouse, CHANRCV}, + {mc->resizec, nil, CHANRCV}, + {kc->c, &r, CHANRCV}, + {nil, nil, CHANEND} + }; + + switch(alt(a)){ + case MOUSE: + mouse(mc); + break; + case RESIZE: + resized(); + break; + case KEYBOARD: + key(r); + break; + } + + redraw(); + } +} + +void +resized(void) +{ + lockdisplay(display); + if(getwindow(display, Refnone) < 0) + sysfatal("couldn't resize"); + unlockdisplay(display); + worldrf.p = Pt2(screen->r.min.x,screen->r.min.y,1); + redraw(); +} -- cgit v1.2.3