diff options
| -rw-r--r-- | .gitignore | 3 | ||||
| -rw-r--r-- | balls.c | 383 | ||||
| -rw-r--r-- | mkfile | 12 |
3 files changed, 398 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..21783e5 --- /dev/null +++ b/.gitignore @@ -0,0 +1,3 @@ +*.o +balls +*.pdf
\ No newline at end of file @@ -0,0 +1,383 @@ +#include <u.h> +#include <libc.h> +#include <stdio.h> +#include <draw.h> +#include <thread.h> +#include <mouse.h> +#include <cursor.h> +#include <keyboard.h> + +#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0])) + +enum { + BG = DWhite, + WALLS = DBlack, + + PAD = 0, + WIDTH = 640, + HEIGHT=480, + + KEY_QUIT = 'q' , + + NBALLS = 2, + RADIUS = 20, + VMAX = 5, + G = 1, + + FPS = 60, + NS_PER_SEC = 1000000000, + FRAME_TIME = NS_PER_SEC / FPS, + TICK_BUFSIZE = 4, + + POS_BUFSIZE = 4, +}; + +typedef struct { + Point pos; + int vx, vy; + int col; + + Channel *frametick; + + Channel **posin; /* receive positions of other balls */ + Channel **posout; /* send position to other balls */ + int nothers; /* number of other balls */ +} BallArg; + +int ballcolors[] = { DRed, DGreen, DBlue }; +Rectangle bounds = {{PAD, PAD}, {PAD+WIDTH, PAD+HEIGHT}}; + +int init(char *label, Mousectl **mctl, Keyboardctl **kctl); +void spawnball(void); +void drawbg(Image *walls, Image *bg); +void spawnballs(int n); +Channel **allocchans(int nchans, int elsize, int nel); +void nooverlapcircles(Point centers[], int n); +Point randptinrect(Rectangle r); +int randint(int lo, int hi); +int isoverlapcircle(Point p, Point q); +int dist(Point p, Point q); +void ball(void *arg); +Image *alloccircle(int fg, int bg); +void drawcircle(Image *m, Point pos); +int clamp(int v, int lo, int hi); +int min(int a, int b); +int max(int a, int b); +void broadcast(Point p, Channel *cs[], int n); +void frametick(void *arg); + +void +threadmain(int argc, char *argv[]) { + Image *bg, *walls; + Mousectl *mctl; + Keyboardctl *kctl; + int resize[2]; + Rune key; + + if (init(argv[0], &mctl, &kctl)) + sysfatal("%s: %r", argv[0]); + + printf("screen: (%d,%d) (%d,%d)\n", screen->r.min.x, screen->r.min.y, + screen->r.max.x, screen->r.max.y); + printf("bounds: (%d,%d) (%d,%d)\n", bounds.min.x, bounds.min.y, + bounds.max.x, bounds.max.y); + + walls = allocimage(display, Rect(0, 0, 1, 1), RGBA32, 1, WALLS); + bg = allocimage(display, bounds, RGBA32, 0, BG); + if (bg == nil || walls == nil) + sysfatal("failed to allocate images"); + + drawbg(walls, bg); + + spawnballs(NBALLS); + + enum { RESIZE = 0, KEYBD = 1 }; + Alt alts[3] = { + {mctl->resizec, &resize, CHANRCV}, + {kctl->c, &key, CHANRCV}, + {nil, nil, CHANEND}, + }; + for (;;) { + switch (alt(alts)) { + case RESIZE: + if (getwindow(display, Refnone) < 0) + sysfatal("%s: %r", argv[0]); + drawbg(walls, bg); + break; + case KEYBD: + if (key == KEY_QUIT) + threadexitsall(0); + break; + case -1: /* interrupted */ + break; + } + } +} + +int +init(char *label, Mousectl **mctl, Keyboardctl **kctl) { + if (initdraw(nil, nil, label) < 0) + return 1; + if ((*mctl = initmouse(nil, screen)) == nil) + return 1; + if ((*kctl = initkeyboard(nil)) == nil) + return 1; + return 0; +} + +void +drawbg(Image *walls, Image *bg) { + draw(screen, screen->r, walls, nil, ZP); + draw(screen, screen->r, bg, nil, ZP); + flushimage(display, Refnone); +} + +void +spawnballs(int n) { + Channel **ticks; + Point *pos; + int i, j; + BallArg *b; + Channel ***poschans; + + if ((ticks = allocchans(n, sizeof(int), TICK_BUFSIZE)) == nil) + sysfatal("failed to allocate frame ticker channels"); + + threadcreate(frametick, ticks, mainstacksize); + + if ((pos = malloc(n*sizeof(Point))) == nil) + sysfatal("failed to allocate position array"); + nooverlapcircles(pos, n); + + if ((poschans = malloc(n*sizeof(Channel **))) == nil) + sysfatal("failed to allocate position channel matrix"); + for (i = 0; i < n; i++) { + if ((poschans[i] = malloc(n*sizeof(Channel *))) == nil) + sysfatal("failed to allocate row of position channel matrix"); + for (j = 0; j < n; j++) { + if (j == i) + continue; + if ((poschans[i][j] = chancreate(sizeof(Point), POS_BUFSIZE)) == nil) + sysfatal("failed to create position channel"); + } + } + + for (i = 0; i < n; i++) { + if ((b = malloc(sizeof(BallArg))) == nil) + sysfatal("failed to allocate ball"); + + b->pos = pos[i]; + b->vx = randint(-VMAX, VMAX+1); + b->vy = randint(-VMAX, VMAX+1); + b->col = ballcolors[randint(0, NELEMS(ballcolors))]; + + b->frametick = ticks[i]; + + if ((b->posin = malloc((n-1)*sizeof(Channel *))) == nil) + sysfatal("failed to allocate array of incoming position channels"); + for (j = 0; j < i; j++) + b->posin[j] = poschans[j][i]; + for (j = i+1; j < n; j++) + b->posin[j-1] = poschans[j][i]; + + if ((b->posout = malloc((n-1)*sizeof(Channel *))) == nil) + sysfatal("failed to allocate array of outgoing position channels"); + memmove(b->posout, poschans[i], i*sizeof(Channel *)); + memmove(b->posout, poschans[i]+i+1, (n-i-1)*sizeof(Channel *)); + + b->nothers = n-1; + + threadcreate(ball, b, mainstacksize); + } + + free(pos); + for (i = 0; i < n; i++) + free(poschans[i]); + free(poschans); +} + +Channel ** +allocchans(int nchans, int elsize, int nel) { + Channel **cs; + int i; + + if (nchans < 0) + return nil; + + if ((cs = malloc((nchans+1)*sizeof(Channel *))) == nil) + return nil; + for (i = 0; i < nchans; i++) { + if ((cs[i] = chancreate(elsize, nel)) == nil) { + while (i-- > 0) + chanfree(cs[i]); + free(cs); + return nil; + } + } + cs[nchans] = nil; + return cs; +} + +void +nooverlapcircles(Point centers[], int n) { + int i, j; + + srand(time(0)); + for (i = 0; i < n; i++) { + centers[i] = randptinrect(insetrect(bounds, RADIUS)); + for (j = 0; j < i; j++) + if (isoverlapcircle(centers[j], centers[i])) + break; + if (j < i) { /* overlapping */ + i--; + continue; + } + } +} + +Point +randptinrect(Rectangle r) { + return Pt(randint(r.min.x, r.max.x), randint(r.min.y, r.max.y)); +} + +int +randint(int lo, int hi) { + return (rand() % (hi-lo)) + lo; +} + +int +isoverlapcircle(Point p, Point q) { + return dist(p, q) < 2*RADIUS; +} + +int +dist(Point p, Point q) { + Rectangle r; + + r = Rpt(p, q); + return sqrt(Dx(r)*Dx(r) + Dy(r)*Dy(r)); +} + +void +ball(void *arg) { + BallArg *b; + Point p1, p2; + Image *fill, *erase; + int t, i, vsum; + float rx, ry; + Point otherpos, vdir; + + b = (BallArg *) arg; + p1 = p2 = b->pos; + + fill = alloccircle(b->col, DTransparent); + erase = alloccircle(BG, DTransparent); + if (fill == nil ||erase == nil) + sysfatal("failed to allocate image"); + + for (;;) { + b->vy += G; + + p2.x += b->vx; + p2.y += b->vy; + + printf("(%d,%d) %d %d\n", b->pos.x, b->pos.y, b->vx, b->vy); + + /* check for wall collision */ + if (p2.x < bounds.min.x+RADIUS || p2.x > bounds.max.x-RADIUS) { + p2.x = clamp(p2.x, bounds.min.x+RADIUS, bounds.max.x-RADIUS); + printf("clamped to %d\n", b->pos.x); + b->vx = -b->vx; + } + if (p2.y < bounds.min.y+RADIUS || p2.y > bounds.max.y-RADIUS) { + p2.y = clamp(p2.y, bounds.min.y+RADIUS, bounds.max.y-RADIUS); + b->vy = -b->vy; + } + + broadcast(p2, b->posout, b->nothers); + + /* check for ball collision */ + for (i = 0; i < b->nothers; i++) { + recv(b->posin[i], &otherpos); + if (isoverlapcircle(p2, otherpos)) { + vdir = subpt(p2, otherpos); + rx = (float) vdir.x / (float) (vdir.x + vdir.y); + ry = (float) vdir.y / (float) (vdir.x + vdir.y); + vsum = b->vx + b->vy; + b->vx = rx * (float) vsum; + b->vy = ry * (float) vsum; + } + } + + recv(b->frametick, &t); + drawcircle(erase, p1); + drawcircle(fill, p2); + p1 = p2; + + } +} + +Image * +alloccircle(int fg, int bg) { + Image *m, *fill +; + m = allocimage(display, Rect(0, 0, 2*RADIUS, 2*RADIUS), RGBA32, 0, bg); + if (m == nil) + return nil; + + fill = allocimage(display, Rect(0, 0, 1, 1), RGBA32, 1, fg); + if (fill == nil) { + free(m); + return nil; + } + + fillellipse(m, Pt(RADIUS, RADIUS), RADIUS, RADIUS, fill, ZP); + freeimage(fill); + return m; +} + + +void +drawcircle(Image *m, Point pos) { + draw(screen, rectaddpt(bounds, subpt(pos, Pt(RADIUS, RADIUS))), m, nil, ZP); +} + +int +clamp(int v, int lo, int hi) { + return min(hi, max(v, lo)); +} + +int +min(int a, int b) { + return (a < b) ? a : b; +} + +int +max(int a, int b) { + return (a > b) ? a : b; +} + +void +broadcast(Point p, Channel *cs[], int n) { + while (n-- > 0) + send(cs[n], &p); +} + +void +frametick(void *arg) { + Channel **cs, **c; + vlong t1, t2; + int s; + + cs = (Channel **) arg; + + t1 = t2 = nsec(); + for (;;) { + while (t2 - t1 < FRAME_TIME) + t2 = nsec(); + t1 = t2; + for (c = cs; *c != nil; c++) + send(*c, &s); + flushimage(display, Refnone); + } +}
\ No newline at end of file @@ -0,0 +1,12 @@ +CC=9c +LD=9l +O=o + +balls: balls.$O + $LD -o balls balls.$O + +%.$O: %.c + $CC $CFLAGS $stem.c + +clean:V: + rm -f balls.$O balls
\ No newline at end of file |