ref: 9090c1e8d2c462e217ab723c684f5a151295a0f6
dir: /main.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include <draw.h>
#include <mouse.h>
#include <keyboard.h>
#include <geometry.h>
#include "dat.h"
#include "fns.h"
double PIX2M = 5;
Mousectl *mc;
Keyboardctl *kc;
Channel *scrsync;
RFrame worldrf;
Projectile ball;
double t0, Δt;
double v0;
double A; /* area of the projectile that meets the air */
Point2 target;
char stats[SLEN][64];
Image *statc;
void *
emalloc(ulong n)
{
void *p;
p = malloc(n);
if(p == nil)
sysfatal("malloc: %r");
memset(p, 0, n);
setmalloctag(p, getcallerpc(&n));
return p;
}
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
∫(double Δt)
{
Point2 Fd; /* drag force */
Fd = mulpt2(mulpt2(ball.v, -vec2len(ball.v)), 0.5 * Cd*ρ*A); /* ½CdρAv² */
ball.v = addpt2(ball.v, mulpt2(addpt2(Vec2(0,-Eg), divpt2(Fd, ball.mass)), Δt));
ball.p = addpt2(ball.p, mulpt2(ball.v, Δt));
snprint(stats[Spos], sizeof(stats[Spos]), "p: %v", ball.p);
snprint(stats[Sdrag], sizeof(stats[Sdrag]), "Fd: %v", divpt2(Fd, ball.mass));
if(ball.p.y <= (2+1)*M2PIX){
ball.p.y = (2+1)*M2PIX;
ball.v = Vec2(0,0);
}
}
void
drawstats(void)
{
int i;
snprint(stats[Svel], sizeof(stats[Svel]), "|v|: %gm/s", vec2len(ball.v));
snprint(stats[Sdeltax], sizeof(stats[Sdeltax]), "Δx: %gm", target.x-ball.p.x);
for(i = 0; i < nelem(stats); i++)
stringn(screen, addpt(screen->r.min, Pt(10, font->height*i+1)), statc, ZP, font, stats[i], sizeof(stats[i]));
}
void
redraw(void)
{
lockdisplay(display);
draw(screen, screen->r, display->black, nil, ZP);
fillellipse(screen, toscreen(ball.p), 2, 2, display->white, ZP);
line(screen, toscreen(Pt2(ball.p.x, 0, 1)), toscreen(target), 0, 0, 1, statc, ZP);
drawstats();
flushimage(display, 1);
unlockdisplay(display);
}
void
mmb(void)
{
enum {
SETV0,
SETPOS,
SETMASS,
SETDIAM,
};
static char *items[] = {
[SETV0] "set v0",
[SETPOS] "set position",
[SETMASS] "set mass",
[SETDIAM] "set diameter",
nil
};
static Menu menu = { .item = items };
char buf[32], *p;
switch(menuhit(2, mc, &menu, nil)){
case SETV0:
snprint(buf, sizeof(buf), "%g", v0);
enter("v0(m/s):", buf, sizeof(buf), mc, kc, nil);
if(buf[0] != 0)
v0 = strtod(buf, nil);
break;
case SETPOS:
snprint(buf, sizeof(buf), "%g, %g", ball.p.x, ball.p.y);
enter("pos(x,y):", buf, sizeof(buf), mc, kc, nil);
if(buf[0] != 0 && (p = strchr(buf, ',')) != nil){
ball.p.x = strtod(buf, nil);
ball.p.y = strtod(p+1, nil);
}
break;
case SETMASS:
snprint(buf, sizeof(buf), "%g", ball.mass);
enter("mass(kg):", buf, sizeof(buf), mc, kc, nil);
if(buf[0] != 0)
ball.mass = strtod(buf, nil);
break;
case SETDIAM:
snprint(buf, sizeof(buf), "%g", 2*ball.r);
enter("diameter(m):", buf, sizeof(buf), mc, kc, nil);
if(buf[0] != 0){
ball.r = strtod(buf, nil)/2;
A = 2*PI*ball.r*ball.r; /* ½(4πr²) */
}
break;
}
}
void
rmb(void)
{
enum {
RST,
QUIT,
};
static char *items[] = {
[RST] "reset",
[QUIT] "quit",
nil,
};
static Menu menu = { .item = items };
switch(menuhit(3, mc, &menu, nil)){
case RST:
ball.p = Pt2((2+1)*M2PIX,(2+1)*M2PIX,1);
ball.v = Vec2(0,0);
break;
case QUIT:
threadexitsall(nil);
}
}
void
zoomin(void)
{
PIX2M += 0.01;
worldrf.bx = Vec2(PIX2M,0);
worldrf.by = Vec2(0,-PIX2M);
snprint(stats[Sscale], sizeof(stats[Sscale]), "s: %gm/pix", M2PIX);
}
void
zoomout(void)
{
PIX2M -= 0.01;
worldrf.bx = Vec2(PIX2M,0);
worldrf.by = Vec2(0,-PIX2M);
snprint(stats[Sscale], sizeof(stats[Sscale]), "s: %gm/px", M2PIX);
}
void
mouse(void)
{
Point2 p;
double θ, dist, eta;
if(ball.p.y <= (2+1)*M2PIX){
p = subpt2(fromscreen(mc->xy), ball.p);
θ = atan2(p.y, p.x);
snprint(stats[Stheta], sizeof(stats[Stheta]), "θ: %g°", θ/DEG);
dist = v0*v0*sin(2*θ)/Eg;
target = Pt2(ball.p.x+dist, 0, 1);
eta = 2*v0*sin(θ)/Eg;
snprint(stats[Seta], sizeof(stats[Seta]), "eta: %gs", eta);
if((mc->buttons & 1) != 0)
ball.v = Vec2(v0*cos(θ), v0*sin(θ));
}
if((mc->buttons & 2) != 0)
mmb();
if((mc->buttons & 4) != 0)
rmb();
if((mc->buttons & 8) != 0)
zoomin();
if((mc->buttons & 16) != 0)
zoomout();
}
void
key(Rune r)
{
switch(r){
case Kdel:
case 'q':
threadexitsall(nil);
}
}
void
resized(void)
{
lockdisplay(display);
if(getwindow(display, Refnone) < 0)
fprint(2, "can't reattach to window\n");
worldrf.p = Pt2(screen->r.min.x, screen->r.max.y, 1);
unlockdisplay(display);
redraw();
}
void
scrsyncproc(void *)
{
for(;;){
send(scrsync, nil);
sleep(HZ2MS(60));
}
}
void
usage(void)
{
fprint(2, "usage: %s\n", argv0);
exits("usage");
}
void
threadmain(int argc, char *argv[])
{
Rune r;
GEOMfmtinstall();
ARGBEGIN{
default: usage();
}ARGEND;
if(initdraw(nil, nil, "ballistics") < 0)
sysfatal("initdraw: %r");
mc = initmouse(nil, screen);
if(mc == nil)
sysfatal("initmouse: %r");
kc = initkeyboard(nil);
if(kc == nil)
sysfatal("initkeyboard: %r");
statc = allocimage(display, Rect(0, 0, 1, 1), screen->chan, 1, DYellow);
if(statc == nil)
sysfatal("allocimage: %r");
snprint(stats[Sscale], sizeof(stats[Sscale]), "s: %gm/pix", M2PIX);
worldrf.p = Pt2(screen->r.min.x, screen->r.max.y, 1);
worldrf.bx = Vec2(PIX2M,0);
worldrf.by = Vec2(0,-PIX2M);
ball.p = Pt2((2+1)*M2PIX,(2+1)*M2PIX,1);
ball.v = Vec2(0, 0);
ball.mass = 0.149;
ball.r = 0.375; /* 3.75cm */
A = 2*PI*ball.r*ball.r; /* ½(4πr²) */
v0 = 53.64; /* avg baseball hit speed */
scrsync = chancreate(1, 0);
display->locking = 1;
unlockdisplay(display);
proccreate(scrsyncproc, 0, mainstacksize);
t0 = nsec();
for(;;){
Alt a[] = {
{mc->c, &mc->Mouse, CHANRCV},
{mc->resizec, nil, CHANRCV},
{kc->c, &r, CHANRCV},
{scrsync, nil, CHANRCV},
{nil, nil, CHANEND}
};
switch(alt(a)){
case 0: mouse(); break;
case 1: resized(); break;
case 2: key(r); break;
case 3: redraw(); break;
}
Δt = (nsec()-t0);
∫(Δt/1e9);
t0 += Δt;
}
}