ref: 0e32e5b28c2b6a343f9899d5375072f797489bf7
parent: 11b5a9d404f0d53e3ba0306ea35cebe0dea534f4
author: rodri <rgl@antares-labs.eu>
date: Sat Jan 28 09:15:21 EST 2023
new toy: barycentric.
--- /dev/null
+++ b/barycentric.c
@@ -1,0 +1,264 @@
+#include <u.h>
+#include <libc.h>
+#include <thread.h>
+#include <draw.h>
+#include <mouse.h>
+#include <keyboard.h>
+#include <geometry.h>
+
+enum {+ PCBg,
+ PCFg,
+ PCPoly,
+ PCPolydark,
+ PCAux,
+ NCOLORS
+};
+
+typedef struct Polygon Polygon;
+
+struct Polygon
+{+ Point2 *pts;
+ Point *scrpts;
+ int npts;
+
+ void (*push)(Polygon*, Point2);
+};
+
+Rectangle UR = {0,0,1,1}; /* unit rectangle */+RFrame worldrf;
+Image *pal[NCOLORS];
+Polygon *thepoly;
+Point2 thepoint;
+
+void resized(void);
+Point toscreen(Point2);
+
+void
+polygonpush(Polygon *poly, Point2 p)
+{+ poly->pts = realloc(poly->pts, ++poly->npts*sizeof(Point2));
+ poly->pts[poly->npts-1] = p;
+ poly->scrpts = realloc(poly->scrpts, (poly->npts+1)*sizeof(Point));
+ poly->scrpts[poly->npts-1] = toscreen(p);
+ poly->scrpts[poly->npts] = poly->scrpts[0]; /* close the polygon */
+}
+
+Polygon*
+newpolygon(Point2 *pts, int npts)
+{+ Polygon *poly;
+ int i;
+
+ poly = malloc(sizeof(Polygon));
+ if(pts == nil){+ poly->pts = nil;
+ poly->scrpts = nil;
+ poly->npts = 0;
+ }else{+ poly->pts = pts;
+ poly->scrpts = malloc((npts+1)*sizeof(Point));
+ for(i = 0; i < npts; i++)
+ poly->scrpts[i] = toscreen(poly->pts[i]);
+ poly->scrpts[npts] = poly->scrpts[0]; /* close the polygon */
+ poly->npts = npts;
+ }
+ poly->push = polygonpush;
+ return poly;
+}
+
+void
+delpolygon(Polygon *poly)
+{+ poly->push = nil;
+ poly->npts = 0;
+ free(poly->scrpts);
+ free(poly->pts);
+ free(poly);
+}
+
+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);
+}
+
+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
+drawinfo(void)
+{+ Triangle2 t;
+ Point3 barypt;
+ Point2 *nextv, *prevv, in0, in1, labelpt;
+ char buf[128];
+ int i;
+
+ if(thepoly->npts < 3)
+ return;
+
+ t.p0 = thepoly->pts[0];
+ t.p1 = thepoly->pts[1];
+ t.p2 = thepoly->pts[2];
+ barypt = barycoords(t, thepoint);
+
+ snprint(buf, sizeof buf, "homo %v", thepoint);
+ string(screen, toscreen(Pt2(Dx(screen->r)/2 - strlen(buf)/2*font->width,10,1)), pal[PCFg], ZP, font, buf);
+
+ snprint(buf, sizeof buf, "bary %V", barypt);
+ string(screen, toscreen(Pt2(Dx(screen->r)/2 - strlen(buf)/2*font->width,10+font->height+2,1)), pal[PCFg], ZP, font, buf);
+
+ /* paint the vertex labels so that they are always visible */
+ for(i = 0; i < thepoly->npts; i++){+ prevv = &thepoly->pts[(i-1+thepoly->npts) % thepoly->npts];
+ nextv = &thepoly->pts[(i+1+thepoly->npts) % thepoly->npts];
+ in0 = normvec2(subpt2(thepoly->pts[i], *prevv));
+ in1 = normvec2(subpt2(thepoly->pts[i], *nextv));
+ labelpt = addpt2(thepoly->pts[i], mulpt2(lerp2(in0, in1, 0.5), 30));
+
+ snprint(buf, sizeof buf, "p%d", i);
+ string(screen, toscreen(labelpt), pal[PCFg], ZP, font, buf);
+ }
+}
+
+void
+redraw(void)
+{+ int i;
+
+ lockdisplay(display);
+ draw(screen, screen->r, pal[PCBg], nil, ZP);
+ fillpoly(screen, thepoly->scrpts, thepoly->npts, 1, pal[PCPoly], ZP);
+ poly(screen, thepoly->scrpts, thepoly->npts > 0? thepoly->npts+1: 0, Enddisc, Enddisc, 1, pal[PCPolydark], ZP);
+ for(i = 0; thepoly->npts > 0 && i < thepoly->npts+1; i++)
+ fillellipse(screen, thepoly->scrpts[i], 2, 2, pal[PCPolydark], ZP);
+ fillellipse(screen, toscreen(thepoint), 2, 2, pal[PCAux], ZP);
+ drawinfo();
+ flushimage(display, 1);
+ unlockdisplay(display);
+}
+
+void
+rmb(Mousectl *mc)
+{+ thepoint = fromscreen(mc->xy);
+}
+
+void
+lmb(Mousectl *mc)
+{+ if(thepoly->npts == 3){+ delpolygon(thepoly);
+ thepoly = newpolygon(nil, 0);
+ }
+ thepoly->push(thepoly, fromscreen(mc->xy));
+}
+
+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;
+
+ 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);
+ thepoly = newpolygon(nil, 0);
+
+ 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();
+}
--- a/mkfile
+++ b/mkfile
@@ -13,6 +13,7 @@
rframeviz\
ptinpoly\
ptintriangle\
+ barycentric\
HFILES=\
libgeometry/geometry.h\