3 #include <msp/game/transform.h>
4 #include "physicalentity.h"
9 Physics::Physics(Game::Stage &s):
11 observer(stage.get_event_bus())
13 observer.observe<Game::Events::EntityCreated>([this](auto &e){ entity_added(e); });
15 stage.synthesize_initial_events(observer);
18 void Physics::entity_added(const Game::Events::EntityCreated &e)
20 if(Game::Handle<PhysicalEntity> physical = dynamic_handle_cast<PhysicalEntity>(e.entity))
22 for(Game::Handle<Game::Entity> p=e.entity->get_parent(); p; p=p->get_parent())
23 if(p->get_transform())
26 SimulatedEntity sim_body;
27 sim_body.entity = physical;
28 if(physical->is_fixture())
30 entities.insert(entities.begin()+fixture_count, sim_body);
34 entities.push_back(sim_body);
38 void Physics::tick(Time::TimeDelta dt)
40 float dt_secs = dt/Time::sec;
42 for(unsigned i=0; i<fixture_count; ++i)
43 copy_in<true>(entities[i]);
44 for(unsigned i=fixture_count; i<entities.size(); ++i)
45 copy_in<false>(entities[i]);
50 for(unsigned i=0; i<10; ++i)
58 for(unsigned i=0; i<fixture_count; ++i)
59 copy_out<true>(entities[i]);
60 for(unsigned i=fixture_count; i<entities.size(); ++i)
61 copy_out<false>(entities[i]);
64 template<bool is_fixture>
65 void Physics::copy_in(SimulatedEntity &entity)
67 Game::Handle<Game::Transform> transform = entity.entity->get_transform();
68 entity.position = transform->get_position().slice<2>(0);
69 const Geometry::Quaternion<float> &r = transform->get_rotation();
70 entity.rotation = Geometry::atan2<float>(2*(r.a*r.d+r.b*r.c), 1-2*(r.c*r.c+r.d*r.d));
72 if constexpr(is_fixture)
73 entity.inverse_mass = 0.0f;
76 Game::Handle<RigidBody> body = entity.entity->get_body();
77 entity.inverse_mass = 1.0f/body->get_mass();
78 entity.velocity = body->get_velocity();
82 template<bool is_fixture>
83 void Physics::copy_out(SimulatedEntity &entity)
85 Game::Handle<Game::Transform> transform = entity.entity->get_transform();
86 transform->set_position(compose(entity.position, 0.0f));
87 transform->set_rotation(Geometry::Quaternion<float>::rotation(entity.rotation, LinAl::Vector<float, 3>(0, 0, 1)));
89 if constexpr(!is_fixture)
91 Game::Handle<RigidBody> body = entity.entity->get_body();
92 body->set_velocity(entity.velocity);
96 void Physics::step(float dt_secs)
98 for(unsigned i=fixture_count; i<entities.size(); ++i)
100 SimulatedEntity &entity = entities[i];
102 LinAl::Vector<float, 2> new_velocity = entity.velocity+entity.external_force*dt_secs*entity.inverse_mass;
103 entity.position += (entity.velocity+new_velocity)*(dt_secs/2);
104 entity.velocity = new_velocity;
108 void Physics::detect_collisions()
110 for(auto &c: collisions)
113 for(unsigned i=fixture_count; i<entities.size(); ++i)
115 Game::Handle<PhysicalEntity> entity1 = entities[i].entity;
116 ColliderType type1 = entity1->get_collider()->get_type();
117 for(unsigned j=0; j<i; ++j)
119 Game::Handle<PhysicalEntity> entity2 = entities[j].entity;
120 ColliderType type2 = entity2->get_collider()->get_type();
121 if(type1==ColliderType::CIRCLE && type2==ColliderType::CIRCLE)
122 collide_circle_circle(i, j);
123 else if(type1==ColliderType::CIRCLE && type2==ColliderType::BOX)
124 collide_circle_box(i, j);
125 else if(type1==ColliderType::BOX && type2==ColliderType::CIRCLE)
126 collide_circle_box(j, i);
131 void Physics::solve_collisions()
133 for(auto &e: entities)
135 e.position_adjust = LinAl::Vector<float, 2>();
136 e.collision_count = 0;
139 for(const auto &c: collisions)
144 SimulatedEntity &entity1 = entities[c.body1];
145 SimulatedEntity &entity2 = entities[c.body2];
146 float inv_mass_sum = 1.0f/(entity1.inverse_mass+entity2.inverse_mass);
147 LinAl::Vector<float, 2> delta = c.normal*c.depth*inv_mass_sum;
148 if(c.body1>=fixture_count)
150 entity1.position_adjust += delta*entity1.inverse_mass;
151 ++entity1.collision_count;
153 if(c.body2>=fixture_count)
155 entity2.position_adjust -= delta*entity1.inverse_mass;
156 ++entity2.collision_count;
160 for(auto &e: entities)
161 if(e.collision_count)
162 e.position += e.position_adjust/static_cast<float>(e.collision_count);
165 void Physics::apply_impulses()
167 for(const auto &c: collisions)
169 SimulatedEntity &entity1 = entities[c.body1];
170 SimulatedEntity &entity2 = entities[c.body2];
171 LinAl::Vector<float, 2> v_rel = entity2.velocity-entity1.velocity;
172 float restitution = 1.0f;
173 float inv_mass_sum = entity1.inverse_mass+entity2.inverse_mass;
174 float impulse = (1+restitution)*inner_product(v_rel, c.normal)/inv_mass_sum;
175 entity1.velocity += c.normal*(impulse*entity1.inverse_mass);
176 entity2.velocity -= c.normal*(impulse*entity2.inverse_mass);
180 Physics::Collision &Physics::get_collision(unsigned i, unsigned j)
182 for(auto &c: collisions)
183 if((c.body1==i && c.body2==j) || (c.body1==j && c.body2==i))
186 Collision &c = collisions.emplace_back();
192 void Physics::collide_circle_circle(unsigned i, unsigned j)
194 const LinAl::Vector<float, 2> &pos1 = entities[i].position;
195 const LinAl::Vector<float, 2> &pos2 = entities[j].position;
196 float r1 = entities[i].entity->get_collider()->get_radius();
197 float r2 = entities[j].entity->get_collider()->get_radius();
199 /* Points in the direction the first body needs to move in to clear the
201 LinAl::Vector<float, 2> delta = pos1-pos2;
202 float d_sq = inner_product(delta, delta);
206 Collision &collision = get_collision(i, j);
207 collision.normal = normalize(delta);
208 collision.depth = r1+r2-sqrt(d_sq);
209 collision.point = pos1-collision.normal*(r1-collision.depth/2);
210 if(collision.body1!=i)
211 collision.normal = -collision.normal;
215 void Physics::collide_circle_box(unsigned i, unsigned j)
217 const LinAl::Vector<float, 2> &pos1 = entities[i].position;
218 const LinAl::Vector<float, 2> &pos2 = entities[j].position;
219 float radius = entities[i].entity->get_collider()->get_radius();
220 LinAl::Vector<float, 2> half_size = entities[j].entity->get_collider()->get_size()/2.0f;
222 LinAl::Vector<float, 2> delta = pos1-pos2;
223 float c = cos(entities[j].rotation);
224 float s = sin(entities[j].rotation);
225 LinAl::Vector<float, 2> local_delta(c*delta.x+s*delta.y, c*delta.y-s*delta.x);
226 LinAl::Vector<float, 2> local_closest(clamp(local_delta.x, -half_size.x, half_size.x), clamp(local_delta.y, -half_size.y, half_size.y));
227 LinAl::Vector<float, 2> local_cdelta = local_delta-local_closest;
228 float d_sq = inner_product(local_cdelta, local_cdelta);
229 if(d_sq<radius*radius)
231 Collision &collision = get_collision(i, j);
232 collision.normal = normalize(LinAl::Vector<float, 2>(c*local_cdelta.x-s*local_cdelta.y, c*local_cdelta.y+s*local_cdelta.x));
233 collision.depth = radius-sqrt(d_sq);
234 collision.point = pos1-collision.normal*(radius-collision.depth/2);
235 if(collision.body1!=i)
236 collision.normal = -collision.normal;