ref: 83b854df0d2a98ca35f8d3215e7fe34531563b20
dir: /sys/src/games/galaxy/body.c/
#include <u.h> #include <libc.h> #include <draw.h> #include <bio.h> #include "galaxy.h" void glxyinit(void) { glxy.a = calloc(5, sizeof(Body)); if(glxy.a == nil) sysfatal("could not allocate glxy: %r"); glxy.nb = 0; glxy.max = 5; } Body* body(void) { Body *b; if(glxy.nb == glxy.max) { glxy.max *= 2; glxy.a = realloc(glxy.a, sizeof(Body) * glxy.max); if(glxy.a == nil) sysfatal("could not realloc glxy: %r"); } b = glxy.a + glxy.nb++; *b = ZB; return b; } Point topoint(Vector v) { Point p; p.x = v.x/scale + orig.x; p.y = v.y/scale + orig.y; return p; } void drawbody(Body *b) { Point pos, v; int s; pos = topoint(b->Vector); s = b->size/scale; fillellipse(screen, pos, s, s, b->col, ZP); v.x = b->v.x/scale*10; v.y = b->v.y/scale*10; if(v.x != 0 || v.y != 0) line(screen, pos, addpt(pos, v), Enddisc, Endarrow, 0, b->col, ZP); flushimage(display, 1); } Vector center(void) { Body *b; Vector gc, gcv; double mass; if(glxy.nb == 0) return (Vector){0, 0}; gc.x = gc.y = gcv.x = gcv.y = mass = 0; for(b = glxy.a; b < glxy.a+glxy.nb; b++) { gc.x += b->x * b->mass; gc.y += b->y * b->mass; gcv.x += b->v.x * b->mass; gcv.y += b->v.y * b->mass; mass += b->mass; } gc.x /= mass; gc.y /= mass; gcv.x /= mass; gcv.y /= mass; for(b = glxy.a; b < glxy.a+glxy.nb; b++) { b->x -= gc.x; b->y -= gc.y; b->v.x -= gcv.x; b->v.y -= gcv.y; } return gc; } int Bfmt(Fmt *f) { Body *b; int r; b = va_arg(f->args, Body*); r = fmtprint(f, "MKBODY %g %g ", b->x, b->y); if(r < 0) return -1; r = fmtprint(f, "%g %g ", b->v.x, b->v.y); if(r < 0) return -1; return fmtprint(f, "%g", b->size); } enum { MKBODY, ORIG, DT, SCALE, GRAV, NOCMD, }; int getcmd(char *l) { static char *cmds[] = { [MKBODY] "MKBODY", [ORIG] "ORIG", [DT] "DT", [SCALE] "SCALE", [GRAV] "GRAV", }; int cmd; for(cmd = 0; cmd < nelem(cmds); cmd++) { if(strcmp(l, cmds[cmd]) == 0) return cmd; } sysfatal("getcmd: no such command %s", l); return NOCMD; } void readglxy(int fd) { static Biobuf bin; char *line; double f; int cmd, len; Body *b; glxy.nb = 0; Binit(&bin, fd, OREAD); for(;;) { line = Brdline(&bin, ' '); len = Blinelen(&bin); if(line == nil) { if(len == 0) break; sysfatal("load: malformed command"); } line[len-1] = '\0'; cmd = getcmd(line); line = Brdline(&bin, '\n'); if(line == nil) { if(len == 0) sysfatal("load: malformed command"); sysfatal("load: read error: %r"); } len = Blinelen(&bin); line[len-1] = '\0'; switch(cmd) { case MKBODY: b = body(); b->x = strtod(line, &line); b->y = strtod(line, &line); b->v.x = strtod(line, &line); b->v.y = strtod(line, &line); b->size = strtod(line, nil); b->mass = b->size*b->size*b->size; b->col = randcol(); CHECKLIM(b, f); break; case ORIG: orig.x = strtol(line, &line, 10); orig.y = strtol(line, nil, 10); break; case DT: dt = strtod(line, nil); dt² = dt*dt; break; case SCALE: scale = strtod(line, nil); break; case GRAV: G = strtod(line, nil); break; } } Bterm(&bin); } void writeglxy(int fd) { static Biobuf bout; Body *b; Binit(&bout, fd, OWRITE); Bprint(&bout, "ORIG %d %d\n", orig.x, orig.y); Bprint(&bout, "SCALE %g\n", scale); Bprint(&bout, "DT %g\n", dt); Bprint(&bout, "GRAV %g\n", G); for(b = glxy.a; b < glxy.a + glxy.nb; b++) Bprint(&bout, "%B\n", b); Bterm(&bout); }