I know its a bit late and this likely won't be read by the OP... But still... Helpful I hope info/ideas/thoughts.

First thing:

Quote:obj = ObjTemplateMgr::getInstance()->createObject( "HumanTemplate", ObjIdType("Human"));

Please let the singleton die the death it deserves! Read up on the forums of why its bad. Its so rarely a valid pattern you should forget it exists, you will KNOW when its actually valid. Also, a high level event system (not huge on the word manager) would solve this for you. As a side note, I call mine a Messaging System, but that's merely a name.

Example:


In my case my "EventSystem" is actually a class that is templated internally so you can have all kinds of messages inside a single class. So your not as limited as say inheriting from an Event class and being stuck with just a few options (send functions).

Also, not sure which article linked in your first post you liked the most but your Entity class pretty much flies in the face of the T=Machine blog posts. Which is actually the system I like the most as it is also the most generic, but yet can be nicely optimized at the same time.

Then again going overly complex in a single person project is just time your spending not making a game...

Now to answer some of your other questions:

Quote:Is a Trigger also an Entity?

I actually think no. I think something like TriggerEvent1234 should be an entity that is made up of a Trigger component, Position component and Script component. This allows a lot more complex game events to take place. Like below...

Quote:When 2 Entities are less than 10 units away from each other, something should happen (like a message or anything). Where in the code do I check whether the two Position components are 10 units away from each other? In the PositionSubSystem?

One solution I came up with as I was reading the question (not done it but think I will try it soon...) is to have the object your concerned about being close to another use the Trigger component and set its cube to be 10 units in size. I can be flat for just hits on its same level, etc. This trigger then could call its own script component and run a custom script upon being triggered.

Quote:Do I have for each single property of an Entity a component? Like Position, Target, Name, Team, ...

Yes, kinda the point. Entity should really be completely empty though you can come up with decent arguments for position but mines still separate and not a pain to access. Target and Team can be kept in AI honestly. I have a CommonInfoComponent that holds things like name and other generic info.

Quote:But for a component like Position I don't see the point of a subsystem, since there's only data in the component.

Its data, but whats wrong with that? You can have things that set/check/get (I hate putting GetX, SetX as methods instead I like readable code like int X() or void Y(int).. etc. Cleaner when you type it out. But this can verify things and allow a lot of other components to get access to it. It can also be packaged into a message (event, though think even message sounds better) and fired off.

Quote:Is Movement not a part of Physics?

Though commonly tied closely together, one doesn't exactly NEED the other and situations can be thought of when movement might not need physics.

Ok, 4 phone calls cause this 10 minute reply to turn into 2 hours. Kinda lost focus. Anyways this just my take on things. My system runs similar to what I described above. Maybe another bit of insight might help who knows.

Quote:
Another thing I came across and don't know how to solve elegantly is whether input events are also normal Events that objects can listen to or whether the InputComponents can check the InputSubsystem for key states. (key states vs key events?)

Have you already implemented input as events? I've seen inputs handled by a single class, and the class interprets the input and creates other Events accordingly. In that implementation, there are no input Events. It makes sense, too. This single class, usually called a controller, is provided to a game view. In that way, you can have 2 different controllers: one for the player (PlayerController), and one for the AI (AIController). Only the PlayerController would be a KeyListener and a MouseListener, so it can receive player input and create Events accordingly. The AIController would only create Events based on your artificial intelligence system (however that works).

Doing it this way, rather than creating a InputSubysytem, removes the necessity of input in your game completely. I can't quite remember what you're doing with your game, but you wouldn't need to worry about input if you wanted to simulate a game with only "bots."

Also, this may not apply too much to your game, but if you had an InputSubsystem, how would you handle other players over a network? If every entity in your game was controlled by a controller (PlayerController, AIController), you would give the networked players their own PlayerController, and then those controllers would read input local to the player, but send the events over the network to the server.

Quote:
I don't want to ask basic questions about Singletons, maybe you can give me a link: what can you do instead of them? I have made my EventManager, my RenderSystem, my InputSystem global Singletons, is that a bad thing? I don't know if passing around pointers to the systems would be better.

Quick and Dirty Answer:

Structure your game differently. If you structure your game to include a game-wide (application-wide) layer, then anything that needs to be accessed from anywhere in the game can be put in that layer. One broad way to structure your game may look like this:



Taken from Game Coding Complete, Second Edition by Mike McShaffry


More on this if you're interested.

Quote:
In my game I have always thought of an event as something that has already happened and not as something that should still happen.

I imagine events as something that is happening right now. The player is accelerating right now so I should play the "player_accelerating" sound effect right now. The player has fired their weapons right now so I should play "player_fired" sound effect right now.

Quote:
So when something happens, other parts of the system can do something in response.

I think of it as all parts of the system reacting simultaneously. The player has pressed the accelerate key, so the physics system would apply a force and the sound system would play a sound effect. Note that if the player is holding down the accelerate key, 1 accelerate event is fired every iteration of your game loop, the systems don't understand the idea of a key being "held down;" each iteration of the game loop the key is either down or not down. That means that every iteration your physics system will apply the force and every iteration your sound system will play the sound. Perhaps you're imagining it as a start event (PlayerAccelerate) and a stop event (PlayerAccelerated), and any time in between, the physics system is applying a constant force and the sound system is looping the sound effect. That may be an interesting way of doing things, but it might turn out to make things more complicated.

If you imagine every iteration of your game loop as a snapshot of your game, independent from the previous iteration and the next iteration, then all that your systems should react to is what is happening right now in your game. If the player is no longer holding down the accelerate key, then there are no more PlayerAccelerate events being fired.

For example, in one iteration of your game loop the accelerate key is down (independent of the fact that it may have just been pressed, or it may have been held down for the entire game). So, your PlayerController does its job and reacts accordingly; it sends a PlayerAccelerate event. The physics system catches the event, applies the force to the player. The sound system catches the event and plays the sound. Let's say that's all that happened in that particular game loop iteration.

Next iteration. There are no keys down, so there are no events fired from the PlayerController; the player will not move and there will be no sound effect played. The enemies are still going about their business, flying around the screen and shooting at the player because they are being controlled by an AIController which isn't going to depend on the player. End of iteration.

Quote:
There is no InputSubSystem. The PlayerController checks for the state of a key an when the up arrow is pressed it sends an PlayerAccelerate event. Then the Physics component catches it and applies the force to the player.

Right. A PlayerAccelerate (which could even be PlayerMove) event would be dispatched to everything that cares. The physics component cares, so it receives the event and applies the appropriate force to the player.

Quote:
But when another component sees the PlayerAccelerate event that doesn't mean the player has accelerated. Would the component that accelerates the player then need to send another event like PlayerAccelerated so that other components know the player has really accelerated?

Explain what you would need a PlayerAccelerated event for. If I imagine what you're getting at, this might be the part where it gets tricky using components and events.

Quote:
In this version the PlayerController is like an InputSubSystem, isn't it?

Yep, except that it won't receive events from the real systems, and every entity in your game has its own controller.

Quote:
What is if I want to have multiple things controlled by the Keyboard? Wouldn't it be better to have an InputSubSystem that takes the input and the PlayerController that checks it? For example when two players play on the same keyboard I have two PlayerControllers but only one InputSubSystem.

You would have 2 different PlayerControllers - Player1Controller and Player2Controller. They would both be KeyListeners, except they would only react to the appropriate keys. For example, Player1Controller would look something like:



Player2Controller would look something like:



Then, in your game, you would give player 1's game entity the Player1Controller and player 2's game entity the Player2Controller, and then all of your enemies would receive different versions of an AIController.

Also, another note on Controllers. The Controllers control the particular entity that they're attached to (duh). This means that you will have a lot of different types of Controllers - Player1Controller, Player2Controller, AIGruntController, AIEliteController, AIHunterController, AIMarineSoldierController, AIMarineSniperController, AIWrathController, AIPelicanController, etc. Also, just to make clear on the PlayerControllers, you probably wouldn't have to differentiate between a Player1Controller and a Player2Controller if your players were not on the same input device (keyboard). If your game was on the Xbox 360, you would have 2 PlayerControllers, except one is listening to controller port 1 and controlling player 1's game entity, and the other is listening to controller port 2 and controlling player 2's game entity.

Hope that clears some confusion. Also, I might have mentioned this already, but there are many ways of achieving the same result. The way I discuss is only one of many, each with its own pros and cons.