void VerletPhysicsSystem::update( EntityManager &entities, EventManager &events, TimeDelta dt )
{
ComponentHandle<VerletBody> body;
for( auto __unused e : entities.entities_with_components( body ) )
{
auto &b = *body.get();
auto current = b.position;
auto velocity = (b.position - b.previous_position) * static_cast<float>((dt / previous_dt)) + b.acceleration * static_cast<float>(dt * dt);
// Friction as viscous drag.
velocity *= (1.0 - b.drag);
/*
// Friction as a fixed-ish force.
// Perhaps do some kind of ground test and apply when things are on ground.
auto l2 = glm::length2(velocity);
if (l2 > 0.0f) {
auto len = std::sqrt(l2);
auto friction = (velocity / len) * std::min(b.friction, len);
velocity -= friction;
}
*/
b.position += velocity;
b.previous_position = current;
// We reset the acceleration so other systems/effects can simply add forces each frame.
// TODO: consider alternative approaches to this.
b.acceleration = vec3(0);
previous_dt = dt;
}
// solve constraints
ComponentHandle<VerletDistanceConstraint> constraint;
const auto constraint_iterations = 2;
for( auto __unused e : entities.entities_with_components( constraint ) )
{
if( (! constraint->a.valid()) || (! constraint->b.valid()) ) {
// would be cooler if the bodies knew about all constraints on them so this couldn't happen.
constraint.remove();
continue;
}
for( int i = 0; i < constraint_iterations; i += 1 ) {
auto &a = *constraint->a.get();
auto &b = *constraint->b.get();
auto center = (a.position + b.position) / 2.0f;
auto delta = a.position - b.position;
auto len = glm::length( delta );
if( len < std::numeric_limits<float>::epsilon() ) {
delta = randVec3();
len = 1.0f;
}
delta *= constraint->distance / (len * 2.0f); // get half delta
a.position = center + delta;
b.position = center - delta;
}
}
}
void soso::applyPhysicsAttraction(EntityManager &entities)
{
ComponentHandle<VerletBody> body;
ComponentHandle<PhysicsAttraction> attraction;
for (auto __unused e : entities.entities_with_components(body, attraction))
{
ComponentHandle<PhysicsAttractor> attractor;
ComponentHandle<VerletBody> attractor_body;
for (auto __unused e : entities.entities_with_components(attractor, attractor_body))
{
auto delta = attractor_body->position - body->position;
auto len = glm::length( delta );
auto t = glm::clamp( len / attractor->distance_falloff, 0.0f, 1.0f );
t = 1.0f - (t * t);
auto force = delta * attractor->strength * attraction->strength * t;
body->nudge( force );
}
}
}
void HudSystem::update(EntityManager& entities,
EventManager& events,
double dt)
{
SpaceShip::Handle spaceShip;
Health::Handle health;
Gun::Handle gun;
for (Entity entity : entities.entities_with_components(spaceShip, health, gun))
{
m_heatBorderSprite.setPosition(50.0f, 485.0f);
m_window.draw(m_heatBorderSprite);
m_heatBarSprite.setPosition(50.0f, 485.0f);
m_heatBarRect.width = static_cast<int>(gun->heat+0.5);
m_heatBarSprite.setTextureRect(m_heatBarRect);
m_window.draw(m_heatBarSprite);
m_healthText.setPosition(50.0f, 500.0f);
m_window.draw(m_healthText);
if (!entity.has_component<DeathSentence>())
{
float startX = 50.0f;
for (int i = 0; i < health->health+1; ++i)
{
m_healthSprite.setPosition(startX, 540.0f);
m_window.draw(m_healthSprite);
startX += 25.0f;
}
}
m_scoreText.setPosition(750.0f, 500.0f);
m_window.draw(m_scoreText);
m_scoreView.setPosition(750.0f, 533.0f);
m_scoreView.draw(spaceShip->score, m_window);
// Only support one space ship atm
return;
}
}
void TransformSystem::update(EntityManager &entities, EventManager &events, TimeDelta dt)
{
ComponentHandle<Transform> transform;
/// If/when entityx allows us to order our components in memory based on their hierarchy,
/// we will be able to walk through and simply update in linear order.
/// We could also do that if we wrote our own memory allocator for transforms (which we are unlikely to pursue).
for (Entity __unused e : entities.entities_with_components(transform))
{
if (transform->isRoot())
{
transform->composeTransform(mat4(1));
transform->descend([] (const Transform &parent, Transform &child) {
child.composeTransform(parent.worldTransform());
});
}
}
}
