/// <summary>
/// Before to start, let's review some of the Svelto.ECS terms:
/// - Entity:
/// it must be a real and concrete entity that you can explain in terms of game design. The name of each
/// entity should reflect a specific concept from the game design domain
/// - Engines (Systems):
/// Where all the logic lies. Engines operates on Entity Components
/// - IEntityComponent:
/// It's an Entity Component which can be used with Pure ECS
/// - IEntityViewComponent:
/// structs implementing this are used to wrap Objects that come from OOP libraries. You will never use it unless
/// you are forced to mix your ECS code with OOP code because of external libraries or platforms. These special
/// "Hybrid" component can hold only interfaces
/// - Implementors:
/// The EntityViewComponent exposed interfaces must be implemented by Implementors that are actually the
/// Objects you need to wrap.
/// - EntityDescriptors:
/// Gives a way to formalise your Entity, it also defines the components that must
/// be generated once the Entity is built
/// </summary>
void CompositionRoot(UnityContext contextHolder)
{
//the UnitySumbmissionEntityViewScheduler is the scheduler that is used by the EnginesRoot to know
//when to submit the entities. Custom ones can be created for special cases.
var unityEntitySubmissionScheduler = new UnityEntitiesSubmissionScheduler("survival");
//The Engines Root is the core of Svelto.ECS. You shouldn't inject the EngineRoot,
//therefore the composition root class must hold a reference or it will be garbage collected.
_enginesRoot = new EnginesRoot(unityEntitySubmissionScheduler);
//The EntityFactory can be injected inside factories (or engine acting as factories) to build new entities
//dynamically
var entityFactory = _enginesRoot.GenerateEntityFactory();
//The entity functions is a set of utility operations on Entities, including removing an entity. I couldn't
//find a better name so far.
var entityFunctions = _enginesRoot.GenerateEntityFunctions();
var entityStreamConsumerFactory = _enginesRoot.GenerateConsumerFactory();
//wrap non testable unity static classes, so that can be mocked if needed (or implementation can change in general, without changing the interface).
IRayCaster rayCaster = new RayCaster();
ITime time = new Time();
//GameObjectFactory allows to create GameObjects without using the Static method GameObject.Instantiate.
//While it seems a complication it's important to keep the engines testable and not coupled with hard
//dependencies
var gameObjectFactory = new GameObjectFactory();
//Player related engines. ALL the dependencies must be solved at this point through constructor injection.
var playerShootingEngine = new PlayerGunShootingEngine(rayCaster, time);
var playerMovementEngine = new PlayerMovementEngine(rayCaster);
var playerAnimationEngine = new PlayerAnimationEngine();
var playerDeathEngine = new PlayerDeathEngine(entityFunctions, entityStreamConsumerFactory);
var playerInputEngine = new PlayerInputEngine();
var playerGunShootingFXsEngine = new PlayerGunShootingFXsEngine(entityStreamConsumerFactory);
//Spawner engines are factories engines that can build entities
var playerSpawnerEngine = new PlayerSpawnerEngine(gameObjectFactory, entityFactory);
var restartGameOnPlayerDeath = new RestartGameOnPlayerDeathEngine();
//Player engines
_enginesRoot.AddEngine(playerMovementEngine);
_enginesRoot.AddEngine(playerAnimationEngine);
_enginesRoot.AddEngine(playerShootingEngine);
_enginesRoot.AddEngine(playerInputEngine);
_enginesRoot.AddEngine(playerGunShootingFXsEngine);
_enginesRoot.AddEngine(playerDeathEngine);
_enginesRoot.AddEngine(playerSpawnerEngine);
_enginesRoot.AddEngine(restartGameOnPlayerDeath);
//Factory is one of the few OOP patterns that work very well with ECS. Its use is highly encouraged
var enemyFactory = new EnemyFactory(gameObjectFactory, entityFactory);
//Enemy related engines
var enemyAnimationEngine = new EnemyChangeAnimationOnPlayerDeath();
var enemyDamageFX = new EnemySpawnEffectOnDamage(entityStreamConsumerFactory);
var enemyAttackEngine = new EnemyAttackEngine(time);
var enemyMovementEngine = new EnemyMovementEngine();
//Spawner engines are factories engines that can build entities
var enemySpawnerEngine = new EnemySpawnerEngine(enemyFactory, entityFunctions);
var enemyDeathEngine = new EnemyDeathEngine(entityFunctions, entityStreamConsumerFactory, time
, new WaitForSubmissionEnumerator(
unityEntitySubmissionScheduler));
//enemy engines
_enginesRoot.AddEngine(enemySpawnerEngine);
_enginesRoot.AddEngine(enemyAttackEngine);
_enginesRoot.AddEngine(enemyMovementEngine);
_enginesRoot.AddEngine(enemyAnimationEngine);
_enginesRoot.AddEngine(enemyDeathEngine);
_enginesRoot.AddEngine(enemyDamageFX);
//abstract engines
var applyDamageEngine = new ApplyDamageToDamageableEntitiesEngine(entityStreamConsumerFactory);
var cameraFollowTargetEngine = new CameraFollowingTargetEngine(time);
var deathEngine = new DispatchKilledEntitiesEngine();
//abstract engines (don't need to know the entity type)
_enginesRoot.AddEngine(applyDamageEngine);
_enginesRoot.AddEngine(deathEngine);
_enginesRoot.AddEngine(cameraFollowTargetEngine);
//hud and sound engines
var hudEngine = new HUDEngine(entityStreamConsumerFactory);
var damageSoundEngine = new DamageSoundEngine(entityStreamConsumerFactory);
var scoreEngine = new UpdateScoreEngine(entityStreamConsumerFactory);
//other engines
_enginesRoot.AddEngine(damageSoundEngine);
_enginesRoot.AddEngine(hudEngine);
_enginesRoot.AddEngine(scoreEngine);
var unsortedEngines = new SurvivalUnsortedEnginesGroup(new FasterList <IStepEngine>(
new IStepEngine[]
{
playerMovementEngine,
playerInputEngine,
playerGunShootingFXsEngine,
playerSpawnerEngine,
playerAnimationEngine,
enemySpawnerEngine,
enemyMovementEngine,
cameraFollowTargetEngine,
hudEngine,
restartGameOnPlayerDeath
}
));
var unsortedDamageEngines = new DamageUnsortedEngines(new FasterList <IStepEngine>(
new IStepEngine[]
{
applyDamageEngine,
damageSoundEngine,
deathEngine
}
));
//Svelto ECS doesn't provide a tick system, hence it doesn't provide a solution to solve the order of execution
//However it provides some option if you want to use them like the SortedEnginesGroup.
_enginesRoot.AddEngine(new TickEnginesGroup(new FasterList <IStepEngine>(new IStepEngine[]
{
unsortedEngines
, playerShootingEngine
, enemyDamageFX
, enemyAttackEngine
, unsortedDamageEngines
, playerDeathEngine
, enemyDeathEngine
, scoreEngine
})));
BuildGUIEntitiesFromScene(contextHolder, entityFactory);
}
/// <summary>
/// Before to start a review of Svelto.ECS terminologies:
/// - Entity:
/// it must be a real and concrete entity that you can explain
/// in terms of game design. The name of each entity should reflect
/// a specific concept from the game design domain
/// - IComponents:
/// Components must be seen as data holders. There are implementing
/// exceptions, but logically it must be still see as a group
/// of readable or writeable data.
/// In Svelto.ECS components are always interfaces declaring
/// Setters and Getters of ValueTypes. DispatchOnSet
/// and DispatchOnChange must not be seen as events, but
/// as pushing of data instead of data polling, similar
/// to the concept of DataBinding.
/// - Implementors:
/// Being components interfaces, they must be implemented through
/// Implementors. The relation Implementors to Components
/// is not 1:1 so that you can, if logic, group several
/// components in one implementor. This allows to easily
/// share data between components. Implementors also act
/// as bridge between the platform and Svelto.ECS.
/// Since Components can hold only value types, Implementors
/// are the objects that can interact directly with the platform
/// objects, I.E.: RigidBody, Transform and so on.
/// Note: IComponents must hold only valuetypes for
/// code design purposes and not optmization purposes.
/// The reason is that all the logic must lie in the engines
/// so Components cannot hold references to instances that can
/// expose functions with logic.
/// - Engines:
/// Where all the logic lies. Engines operates on EntityViews
/// - EntityViews:
/// EntityViews maps EntityComponents. The Engines can't
/// access directly to each entity (as a single set of components), but
/// through a component sets defined by EntityView.
/// They act as a component filters and expose only the entity components
/// that the Engine is interested in.
/// EntityViews are actually defined by the need of the Engine so they
/// come together with the engine and in the same namespace of the engine.
/// - EntityStructs:
/// In order to write Data Oriented Cache Friendly code, Svelto.ECS
/// also support EntityStructs. Please check other examples to
/// understand how to use them. However know that this kind of
/// optimizations is very limited to special circumstances
/// so the flexibility of EntityViews is most of the times what you need.
/// - EntityDescriptors:
/// Gives a way to formalize your Entity in svelto.ECS, it also
/// groups the EntityViews that must be generated once the
/// Entity is built
/// </summary>
void SetupEnginesAndEntities()
{
//The Engines Root is the core of Svelto.ECS. You must NEVER inject the EngineRoot
//as it is, therefore the composition root must hold a reference or it will be
//GCed.
//the UnitySumbmissionEntityViewScheduler is the scheduler that is used by the EnginesRoot to know
//when to inject the EntityViews. You shouldn't use a custom one unless you know what you
//are doing or you are not working with Unity.
_enginesRoot = new EnginesRoot(new UnitySumbmissionEntityViewScheduler());
//Engines root can never be held by anything else than the context itself to avoid leaks
//That's why the EntityFactory and EntityFunctions are generated.
//The EntityFactory can be injected inside factories (or engine acting as factories)
//to build new entities dynamically
_entityFactory = _enginesRoot.GenerateEntityFactory();
//The entity functions is a set of utility operations on Entities, including
//removing an entity. I couldn't find a better name so far.
var entityFunctions = _enginesRoot.GenerateEntityFunctions();
//GameObjectFactory allows to create GameObjects without using the Static
//method GameObject.Instantiate. While it seems a complication
//it's important to keep the engines testable and not
//coupled with hard dependencies references (read my articles to understand
//how dependency injection works and why solving dependencies
//with static classes and singletons is a terrible mistake)
GameObjectFactory factory = new GameObjectFactory();
//the ISequencer is one of the 3 official ways available in Svelto.ECS
//to communicate. They are mainly used for two specific cases:
//1) specify a strict execution order between engines (engine logic
//is executed horizontally instead than vertically, I will talk about this
//in my articles). 2) filter a data token passed as parameter through
//engines. The ISequencer is also not the common way to communicate
//between engines
Sequencer playerDamageSequence = new Sequencer();
Sequencer enemyDamageSequence = new Sequencer();
Sequencer enemyWaveSequence = new Sequencer();
Sequencer enemySpawnSequence = new Sequencer();
Sequencer bonusHealthSequence = new Sequencer();
Sequencer bonusAmmoSequence = new Sequencer();
Sequencer bonusHealthSpawnSequence = new Sequencer();
Sequencer bonusAmmoSpawnSequence = new Sequencer();
Sequencer ammoUpdateSequence = new Sequencer();
Sequencer pushPowerSequence = new Sequencer();
//wrap non testable unity static classes, so that
//can be mocked if needed.
IRayCaster rayCaster = new RayCaster();
ITime time = new Time();
//Player related engines. ALL the dependecies must be solved at this point
//through constructor injection.
var playerHealthEngine = new HealthEngine(playerDamageSequence);
var playerShootingEngine = new PlayerGunShootingEngine(enemyDamageSequence, ammoUpdateSequence, rayCaster, time);
var playerMovementEngine = new PlayerMovementEngine(rayCaster, time);
var playerAnimationEngine = new PlayerAnimationEngine();
var playerDeathEngine = new PlayerDeathEngine(entityFunctions);
//Enemy related engines
var enemyAnimationEngine = new EnemyAnimationEngine();
//HealthEngine is a different object for the enemy because it uses a different sequence
var enemyHealthEngine = new HealthEngine(enemyDamageSequence);
var enemyAttackEngine = new EnemyAttackEngine(playerDamageSequence, time);
var enemyMovementEngine = new EnemyMovementEngine();
var enemySpawnerEngine = new EnemySpawnerEngine(enemyWaveSequence, enemySpawnSequence, factory, _entityFactory);
var enemyDeathEngine = new EnemyDeathEngine(entityFunctions, time);
var enemyWaveEngine = new EnemyWaveEngine(enemyWaveSequence);
//bonus engines
var bonusHealthEngine = new BonusHealthEngine(bonusHealthSequence);
var bonusCollectedEngine = new BonusCollectedEngine(entityFunctions);
var bonusAnimationEngine = new BonusAnimationEngine();
var bonusHealthSpawnerEngine = new BonusHealthSpawnerEngine(bonusHealthSpawnSequence, factory, _entityFactory);
var bonusAmmoSpawnerEngine = new BonusAmmoSpawnerEngine(bonusAmmoSpawnSequence, factory, _entityFactory);
var bonusAmmoEngine = new BonusAmmoEngine(bonusAmmoSequence);
var bonusSoundEngine = new BonusSoundEngine();
//powers engines
var pushPowerEngine = new PushPowerEngine(pushPowerSequence, time);
var powerSoundEngine = new PowerSoundEngine();
//hud and sound engines
var hudEngine = new HUDEngine(time);
var enemyCountEngine = new EnemyHUDEngine();
var damageSoundEngine = new DamageSoundEngine();
var scoreEngine = new ScoreEngine();
//The ISequencer implementaton is very simple, but allows to perform
//complex concatenation including loops and conditional branching.
#region "Setting Sequences"
playerDamageSequence.SetSequence(
new Steps //sequence of steps, this is a dictionary!
{
{ //first step
enemyAttackEngine, //this step can be triggered only by this engine through the Next function
new To //this step can lead only to one branch
{
//this is the only engine that will be called when enemyAttackEngine triggers Next()
new IStep[] { playerHealthEngine }
}
},
{ //second step
playerHealthEngine, //this step can be triggered only by this engine through the Next function
new To //once the playerHealthEngine calls step, all these engines will be called at once
//depending by the condition a different set of engines will be triggered. The
//order of the engines triggered is guaranteed.
{
//these engines will be called when the Next function is called with the DamageCondition.damage set
{ DamageCondition.Damage, new IStep[] { hudEngine, damageSoundEngine } },
//these engines will be called when the Next function is called with the DamageCondition.dead set
{ DamageCondition.Dead, new IStep[] {
hudEngine, damageSoundEngine,
playerMovementEngine, playerAnimationEngine,
enemyAnimationEngine, playerDeathEngine
} }
}
}
}
);
enemyDamageSequence.SetSequence(
new Steps
{
{
playerShootingEngine,
new To
{
//in every case go to enemyHealthEngine
new IStep[] { enemyHealthEngine }
}
},
{
enemyHealthEngine,
new To
{
{ DamageCondition.Damage, new IStep[] { enemyAnimationEngine, damageSoundEngine } },
{ DamageCondition.Dead, new IStep[] { scoreEngine, enemyMovementEngine, enemyAnimationEngine,
enemySpawnerEngine, enemyCountEngine, damageSoundEngine, enemyDeathEngine } },
}
}
}
);
enemyWaveSequence.SetSequence(
new Steps
{
{
enemySpawnerEngine,
new To
{
enemyWaveEngine,
}
},
{
enemyWaveEngine,
new To
{
{ WaveCondition.Next, new IStep[] { enemySpawnerEngine, enemyCountEngine, hudEngine } },
{ WaveCondition.Last, new IStep[] { enemySpawnerEngine, enemyCountEngine, hudEngine } },
{ WaveCondition.Stop, new IStep[] { hudEngine } },
}
}
}
);
enemySpawnSequence.SetSequence(
new Steps
{
{
enemySpawnerEngine,
new To
{
enemyMovementEngine,
}
}
}
);
bonusHealthSequence.SetSequence(
new Steps
{
{
bonusHealthEngine,
new To
{
{ new IStep[] { playerHealthEngine, hudEngine, bonusSoundEngine, bonusAnimationEngine,
bonusCollectedEngine } }
}
}
}
);
bonusHealthSpawnSequence.SetSequence(
new Steps
{
{
bonusHealthSpawnerEngine,
new To
{
bonusSoundEngine,
}
}
}
);
bonusAmmoSpawnSequence.SetSequence(
new Steps
{
{
bonusAmmoSpawnerEngine,
new To
{
bonusSoundEngine,
}
}
}
);
ammoUpdateSequence.SetSequence(
new Steps
{
{
playerShootingEngine,
new To
{
hudEngine,
}
}
}
);
bonusAmmoSequence.SetSequence(
new Steps
{
{
bonusAmmoEngine,
new To
{
{ new IStep[] { playerShootingEngine, hudEngine, bonusSoundEngine, bonusAnimationEngine,
bonusCollectedEngine } }
}
}
}
);
pushPowerSequence.SetSequence(
new Steps
{
{
pushPowerEngine,
new To
{
{ PowerCondition.Start, new IStep[] { powerSoundEngine, hudEngine } },
{ PowerCondition.Stop, new IStep[] { powerSoundEngine } },
}
}
}
);
#endregion
//Mandatory step to make engines work
//Player engines
_enginesRoot.AddEngine(playerMovementEngine);
_enginesRoot.AddEngine(playerAnimationEngine);
_enginesRoot.AddEngine(playerShootingEngine);
_enginesRoot.AddEngine(playerHealthEngine);
_enginesRoot.AddEngine(new PlayerInputEngine());
_enginesRoot.AddEngine(new PlayerGunShootingFXsEngine());
//enemy engines
_enginesRoot.AddEngine(enemySpawnerEngine);
_enginesRoot.AddEngine(enemyWaveEngine);
_enginesRoot.AddEngine(enemyAttackEngine);
_enginesRoot.AddEngine(enemyMovementEngine);
_enginesRoot.AddEngine(enemyAnimationEngine);
_enginesRoot.AddEngine(enemyHealthEngine);
_enginesRoot.AddEngine(enemyDeathEngine);
//bonus engines
_enginesRoot.AddEngine(bonusHealthEngine);
_enginesRoot.AddEngine(bonusAmmoEngine);
_enginesRoot.AddEngine(bonusCollectedEngine);
_enginesRoot.AddEngine(bonusAnimationEngine);
_enginesRoot.AddEngine(bonusHealthSpawnerEngine);
_enginesRoot.AddEngine(bonusAmmoSpawnerEngine);
//powers engines
_enginesRoot.AddEngine(powerSoundEngine);
_enginesRoot.AddEngine(pushPowerEngine);
//other engines
_enginesRoot.AddEngine(new CameraFollowTargetEngine(time));
_enginesRoot.AddEngine(damageSoundEngine);
_enginesRoot.AddEngine(bonusSoundEngine);
_enginesRoot.AddEngine(hudEngine);
_enginesRoot.AddEngine(scoreEngine);
_enginesRoot.AddEngine(enemyCountEngine);
}