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Diffstat (limited to 'main.c')
| -rw-r--r-- | main.c | 285 |
1 files changed, 285 insertions, 0 deletions
@@ -0,0 +1,285 @@ +#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" + +RFrame screenrf; +State state; +double timestep; + + +double min(double a, double b) { return a < b? a: b; } +double max(double a, double b) { return a > b? a: b; } + +/* + * Dynamics stepper + * + * Currently set to a basic spring-damper system. + */ +double +accel(State *s, double t) +{ + static double k = 15, b = 0.1; + + USED(t); + return -k*s->x - b*s->v; +} + +Derivative +eval(State *s0, double t, double Δt, Derivative *d) +{ + State s; + Derivative res; + + s.x = s0->x + d->dx*Δt; + s.v = s0->v + d->dv*Δt; + + res.dx = s.v; + res.dv = accel(&s, t+Δt); + return res; +} + +/* + * Explicit Euler Integrator + */ +void +euler0(State *s, double t, double Δt) +{ + static Derivative ZD = {0,0}; + Derivative d; + + d = eval(s, t, Δt, &ZD); + + s->x += d.dx*Δt; + s->v += d.dv*Δt; +} + +/* + * Semi-implicit Euler Integrator + */ +void +euler1(State *s, double t, double Δt) +{ + static Derivative ZD = {0,0}; + Derivative d; + + d = eval(s, t, Δt, &ZD); + + s->v += d.dv*Δt; + s->x += s->v*Δt; +} + +/* + * RK4 Integrator + */ +void +rk4(State *s, double t, double Δt) +{ + static Derivative ZD = {0,0}; + Derivative a, b, c, d; + double dxdt, dvdt; + + a = eval(s, t, 0, &ZD); + b = eval(s, t, Δt/2, &a); + c = eval(s, t, Δt/2, &b); + d = eval(s, t, Δt, &c); + + dxdt = 1.0/6 * (a.dx + 2*(b.dx + c.dx) + d.dx); + dvdt = 1.0/6 * (a.dv + 2*(b.dv + c.dv) + d.dv); + + s->x += dxdt*Δt; + s->v += dvdt*Δt; +} + +/* + * The Integrator + */ +void +integrate(State *s, double t, double Δt) +{ + //euler0(s, t, Δt); + //euler1(s, t, Δt); + rk4(s, t, Δt); +} + +Point +toscreen(Point2 p) +{ + p = invrframexform(p, screenrf); + return Pt(p.x,p.y); +} + +Point2 +fromscreen(Point p) +{ + return rframexform(Pt2(p.x,p.y,1), screenrf); +} + +void +drawtimestep(double t) +{ + char buf[32]; + + snprint(buf, sizeof buf, "t=%gs", t); + string(screen, addpt(screen->r.min, Pt(10,10)), display->white, ZP, font, buf); +} + +void +drawbar(double v) +{ + struct { + Point2 p0, p1; + } l = { + Pt2(-2,v,1), + Pt2(2,v,1) + }; + char buf[32]; + + line(screen, toscreen(l.p0), toscreen(l.p1), 0, 0, 0, display->white, ZP); + snprint(buf, sizeof buf, "%.3f", v); + l.p1.x += 10; + string(screen, toscreen(l.p1), display->white, ZP, font, buf); +} + +void +redraw(void) +{ + lockdisplay(display); + + draw(screen, screen->r, display->black, nil, ZP); + drawtimestep(timestep); + drawbar(state.min); drawbar(state.max); drawbar(state.avg); + fillellipse(screen, toscreen(Pt2(0,state.x,1)), 2, 2, display->white, ZP); + + flushimage(display, 1); + unlockdisplay(display); +} + +void +resized(void) +{ + lockdisplay(display); + if(getwindow(display, Refnone) < 0) + sysfatal("resize failed"); + unlockdisplay(display); + screenrf.p = Pt2(screen->r.min.x+Dx(screen->r)/2,screen->r.max.y-Dy(screen->r)/2,1); + redraw(); +} + +void +rmb(Mousectl *mc) +{ + enum { + RESET, + }; + static char *items[] = { + [RESET] "reset", + nil + }; + static Menu menu = { .item = items }; + + switch(menuhit(3, mc, &menu, _screen)){ + case RESET: + //resetsim(); + break; + } +} + +void +mouse(Mousectl *mc, Keyboardctl *) +{ + 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; + double t, Δt; + + 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"); + screenrf.p = Pt2(screen->r.min.x+Dx(screen->r)/2,screen->r.max.y-Dy(screen->r)/2,1); + screenrf.bx = Vec2(1, 0); + screenrf.by = Vec2(0,-1); + + t = 0; + Δt = 0.01; + state.x = 100; + state.v = 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, CHANNOBLK} + }; + + switch(alt(a)){ + case MOUSE: + mouse(mc, kc); + break; + case RESIZE: + resized(); + break; + case KEYBOARD: + key(r); + break; + } + + integrate(&state, t, Δt); + + state.acc += state.x; + state.avg = state.acc/++state.nsteps; + state.min = min(state.min, state.x); + state.max = max(state.max, state.x); + + redraw(); + + t += Δt; + timestep = t; + + sleep(66); + } +} |