X-Git-Url: https://git.localhorst.tv/?a=blobdiff_plain;ds=sidebyside;f=src%2Fworld%2FWorld.cpp;fp=src%2Fworld%2FWorld.cpp;h=dcac95eb72708791b37b15f4a29a76035aa0e503;hb=e4732374394610bdd3deafd2138cbea267a670e0;hp=53115dc386360b73558a07ae5ee00bafe381c9e2;hpb=79dbf3ed50c70107164d0473bd7479ee680d6e70;p=gworm.git

diff --git a/src/world/World.cpp b/src/world/World.cpp
index 53115dc..dcac95e 100644
--- a/src/world/World.cpp
+++ b/src/world/World.cpp
@@ -15,12 +15,107 @@ World::World(Vector<int> size)
 
 
 void World::Update(float dt) {
+	constexpr float fricDyn = 0.75f;
+	constexpr float fricStat = 2.5f;
+	constexpr float dragFact = 0.05f;
+
 	for (Entity &e : entities) {
-		e.acc = ForceAt(e.pos, e.mass) / e.mass;
+		const Vector<float> gravity = ForceAt(e.pos, e.mass);
+		const Vector<float> drag = Rotate180(e.vel) * dragFact;
+		// TODO: drag should be inverse square. and not onmipresent
+
+		e.acc = (gravity + drag) / e.mass;
 		e.Update(dt);
+
+		Vector<float> at;
+		if (WorldCollision(e, at)) {
+			float speed = Length(e.vel);
+			Vector<float> normVel = e.vel / speed;
+			float steps = 0;
+			while (MassAt(e.pos) > 0) {
+				e.pos -= normVel;
+				steps += 1.0f;
+			}
+			const Vector<float> normal = NormalAt(e.pos + normVel);
+			e.vel = Reflect(e.vel, normal);
+			speed = Length(e.vel);
+			normVel = e.vel / speed;
+			// some kind of friction, depends on angle to normal
+			speed *= (fricDyn * (std::abs(Dot(normVel, normal))));
+			if (speed > fricStat) {
+				speed -= fricStat;
+				e.vel = normVel * speed;
+				e.pos += normVel * steps;
+			} else {
+				e.vel = Vector<float>(0, 0);
+			}
+		}
+	}
+}
+
+
+bool World::WorldCollision(const Entity &e, Vector<float> &at) const {
+	if (InBounds(e.pos) && MassAt(e.pos) > 0) {
+		at = e.pos;
+		return true;
+	} else {
+		return false;
 	}
 }
 
+Vector<float> World::NormalAt(Vector<float> pos) const {
+	constexpr Vector<float> check[] = {
+		{  0,        -2        },
+		{  0.765367, -1.84776  },
+		{  1.41421,  -1.41421  },
+		{  1.84776,  -0.765367 },
+		{  2,         0        },
+		{  1.84776,   0.765367 },
+		{  1.41421,   1.41421  },
+		{  0.765367,  1.84776  },
+		{  0,         2        },
+		{ -0.765367,  1.84776  },
+		{ -1.41421,   1.41421  },
+		{ -1.84776,   0.765367 },
+		{ -2,         0        },
+		{ -1.84776,  -0.765367 },
+		{ -1.41421,  -1.41421  },
+		{ -0.765367, -1.84776  },
+	};
+	Vector<float> normal;
+	for (auto v : check) {
+		if (MassAt(pos + v) == 0) {
+			normal += v;
+		}
+	}
+	return Norm(normal);
+}
+
+//Vector<float> World::NormalAt(Vector<float> pos) const {
+//	Vector<int> begin(pos - Vector<float>(3, 3));
+//	Vector<int> end(pos + Vector<float>(3, 3));
+//
+//	Vector<float> normal;
+//	for (Vector<int> cur(begin); cur.y < end.y; ++cur.y) {
+//		for (cur.x = begin.x; cur.x < end.x; ++cur.x) {
+//			if (IsSurface(cur) > 0) {
+//				const Vector<float> dir = pos - Vector<float>(cur);
+//				normal += Rotate90(dir);
+//			}
+//		}
+//	}
+//
+//	return Norm(normal);
+//}
+
+bool World::IsSurface(Vector<int> pos) const {
+	return MassAt(pos) > 0 && (
+			MassAt(pos - Vector<int>(1, 0)) == 0 ||
+			MassAt(pos + Vector<int>(1, 0)) == 0 ||
+			MassAt(pos - Vector<int>(0, 1)) == 0 ||
+			MassAt(pos + Vector<int>(0, 1)) == 0);
+}
+
 
 Entity &World::AddEntity(const Entity &e) {
 	entities.emplace_back(e);