ref: 1059aa8707299a104a0ba556d293436d960e0006
parent: 8731378bba72cf2a5084f90fb375c998f2be6472
author: rodri <rgl@antares-labs.eu>
date: Mon Aug 2 15:00:14 EDT 2021
implemented complete universe particles integration.
--- a/fns.h
+++ b/fns.h
@@ -11,6 +11,7 @@
* physics
*/
void integrate(GameState*, double, double);
+void integrateu(Universe*, double, double);
/*
* nanosec
--- a/physics.c
+++ b/physics.c
@@ -18,25 +18,6 @@
return Vec2(0, -k*s->p.y - b*s->v.y);
}
-/*
- * XXX: remember to take thrust into account, based on user input.
- */
-static Point2
-accelship(Universe *u, Ship *s, double)
-{- double g, d;
-
- d = vec2len(subpt2(u->star.p, s->p));
- g = G*u->star.mass/(d*d);
- return mulpt2(normvec2(subpt2(u->star.p, s->p)), g);
-}
-
-static Point2
-accelbullet(Universe *, Bullet *, double)
-{- return Vec2(0,0);
-}
-
static Derivative
eval(GameState *s0, double t, double Δt, Derivative *d)
{@@ -112,4 +93,76 @@
//euler0(s, t, Δt);
//euler1(s, t, Δt);
rk4(s, t, Δt);
+}
+
+/*
+ *
+ * UNIVERSE MIGRATION. KEEP CALM AND FASTEN YOUR SEAT BELTS.
+ *
+ */
+
+/*
+ * XXX: remember to take thrust into account, based on user input.
+ */
+static Point2
+accelship(Universe *u, Particle *p, double)
+{+ double g, d;
+
+ d = vec2len(subpt2(u->star.p, p->p));
+ d *= 1e5; /* scale to the 100km/px range */
+ g = G*u->star.mass/(d*d);
+ return mulpt2(normvec2(subpt2(u->star.p, p->p)), g);
+}
+
+static Point2
+accelbullet(Universe *, Particle *, double)
+{+ return Vec2(0,0);
+}
+
+static Derivative
+evalu(Universe *u, Particle *p0, double t, double Δt, Derivative *d, Point2 (*a)(Universe*,Particle*,double))
+{+ Particle p;
+ Derivative res;
+
+ p.p = addpt2(p0->p, mulpt2(d->dx, Δt));
+ p.v = addpt2(p0->v, mulpt2(d->dv, Δt));
+
+ res.dx = p.v;
+ res.dv = a(u, &p, t+Δt);
+ return res;
+}
+
+static void
+rk4u(Universe *u, Particle *p, double t, double Δt, Point2 (*acc)(Universe*,Particle*,double))
+{+ static Derivative ZD = {0};+ Derivative a, b, c, d;
+ Point2 dxdt, dvdt;
+
+ a = evalu(u, p, t, 0, &ZD, acc);
+ b = evalu(u, p, t, Δt/2, &a, acc);
+ c = evalu(u, p, t, Δt/2, &b, acc);
+ d = evalu(u, p, t, Δt, &c, acc);
+
+ dxdt = divpt2(addpt2(addpt2(a.dx, mulpt2(addpt2(b.dx, c.dx), 2)), d.dx), 6);
+ dvdt = divpt2(addpt2(addpt2(a.dv, mulpt2(addpt2(b.dv, c.dv), 2)), d.dv), 6);
+
+ p->p = addpt2(p->p, mulpt2(dxdt, Δt));
+ p->v = addpt2(p->v, mulpt2(dvdt, Δt));
+}
+
+void
+integrateu(Universe *u, double t, double Δt)
+{+ int i, j;
+
+ for(i = 0; i < nelem(u->ships); i++){+ rk4u(u, &u->ships[i], t, Δt, accelship);
+ for(j = 0; j < nelem(u->ships[i].rounds); j++)
+ if(u->ships[i].rounds[j].fired)
+ rk4u(u, &u->ships[i].rounds[j], t, Δt, accelbullet);
+ }
}
--- a/universe.c
+++ b/universe.c
@@ -8,7 +8,7 @@
static void
universe_step(Universe *u, double Δt)
{- //integrate(u, u->t, Δt);
+ integrateu(u, u->t, Δt);
}
static void