slightly better physics

[blobs.git] / src / creature / creature.cpp

diff --git a/src/creature/creature.cpp b/src/creature/creature.cpp
index dc857ceb08bd637460ee7b4954a95e7c17dd0275..b95b531a13097041c2b7e835d4d69483f3798446 100644 (file)
--- a/src/creature/creature.cpp
+++ b/src/creature/creature.cpp
@@ -278,10 +278,11 @@ void Creature::TickState(double dt) {
        );
        state.pos += f.vel * dt;
        state.vel += f.acc * dt;
+       situation.EnforceConstraints(state);
        if (length2(state.vel) > 0.000001) {
                glm::dvec3 nvel(normalize(state.vel));
                double ang = angle(nvel, state.dir);
-               double turn_rate = PI * 0.5 * dt;
+               double turn_rate = PI * 0.75 * dt;
                if (ang < turn_rate) {
                        state.dir = normalize(state.vel);
                } else if (std::abs(ang - PI) < 0.001) {
@@ -291,16 +292,33 @@ void Creature::TickState(double dt) {
                }
        }
        situation.SetState(state);
-       stats.Exhaustion().Add(length(f.acc) * Mass() / Stamina() * dt);
+       stats.Exhaustion().Add(length(f.acc) * Mass() / Stamina() * 0.5 * dt);
 }
 
 Situation::Derivative Creature::Step(const Situation::Derivative &ds, double dt) const noexcept {
        Situation::State s = situation.GetState();
        s.pos += ds.vel * dt;
        s.vel += ds.acc * dt;
+       glm::dvec3 force(steering.Force(s));
+       // gravity = antinormal * mass * Gm / r²
+       double elevation = s.pos[(situation.Surface() + 2) % 3];
+       glm::dvec3 normal(world::Planet::SurfaceNormal(situation.Surface()));
+       force += glm::dvec3(
+               -normal
+               * Mass() * situation.GetPlanet().GravitationalParameter()
+               / (elevation * elevation));
+       // if net force is applied and in contact with surface
+       if (!allzero(force) && std::abs(std::abs(elevation) - situation.GetPlanet().Radius()) < 0.001) {
+               // apply friction = -|normal force| * tangential force * coefficient
+               glm::dvec3 fn(normal * dot(force, normal));
+               glm::dvec3 ft(force - fn);
+               double u = 0.4;
+               glm::dvec3 friction(-length(fn) * ft * u);
+               force += friction;
+       }
        return {
                s.vel,
-               steering.Force(s) / Mass()
+               force / Mass()
        };
 }
 
@@ -576,7 +594,7 @@ void Split(Creature &c) {
        // TODO: duplicate situation somehow
        a->GetSituation().SetPlanetSurface(
                s.GetPlanet(), s.Surface(),
-               s.Position() + glm::dvec3(0.0, a->Size() + 0.1, 0.0));
+               s.Position() + glm::dvec3(0.0, 0.55 * a->Size(), 0.0));
        a->BuildVAO();
        std::cout << "[" << int(c.GetSimulation().Time()) << "s] "
                << a->Name() << " was born" << std::endl;
@@ -590,7 +608,7 @@ void Split(Creature &c) {
        s.GetPlanet().AddCreature(b);
        b->GetSituation().SetPlanetSurface(
                s.GetPlanet(), s.Surface(),
-               s.Position() + glm::dvec3(0.0, b->Size() - 0.1, 0.0));
+               s.Position() - glm::dvec3(0.0, 0.55 * b->Size(), 0.0));
        b->BuildVAO();
        std::cout << "[" << int(c.GetSimulation().Time()) << "s] "
                << b->Name() << " was born" << std::endl;
@@ -700,12 +718,26 @@ const world::TileType &Situation::GetTileType() const noexcept {
 
 void Situation::Move(const glm::dvec3 &dp) noexcept {
        state.pos += dp;
+       EnforceConstraints(state);
+}
+
+void Situation::Accelerate(const glm::dvec3 &dv) noexcept {
+       state.vel += dv;
+       EnforceConstraints(state);
+}
+
+void Situation::EnforceConstraints(State &s) noexcept {
        if (OnSurface()) {
-               // enforce ground constraint
                if (Surface() < 3) {
-                       state.pos[(Surface() + 2) % 3] = std::max(0.0, state.pos[(Surface() + 2) % 3]);
+                       if (s.pos[(Surface() + 2) % 3] < GetPlanet().Radius()) {
+                               s.pos[(Surface() + 2) % 3] = GetPlanet().Radius();
+                               s.vel[(Surface() + 2) % 3] = std::max(0.0, s.vel[(Surface() + 2) % 3]);
+                       }
                } else {
-                       state.pos[(Surface() + 2) % 3] = std::min(0.0, state.pos[(Surface() + 2) % 3]);
+                       if (s.pos[(Surface() + 2) % 3] > -GetPlanet().Radius()) {
+                               s.pos[(Surface() + 2) % 3] = -GetPlanet().Radius();
+                               s.vel[(Surface() + 2) % 3] = std::min(0.0, s.vel[(Surface() + 2) % 3]);
+                       }
                }
        }
 }
@@ -715,6 +747,7 @@ void Situation::SetPlanetSurface(world::Planet &p, int srf, const glm::dvec3 &po
        planet = &p;
        surface = srf;
        state.pos = pos;
+       EnforceConstraints(state);
 }
 
 
@@ -746,7 +779,7 @@ void Steering::DontSeparate() noexcept {
 }
 
 void Steering::ResumeSeparate() noexcept {
-       separating = false;
+       separating = true;
 }
 
 void Steering::Halt() noexcept {