Game design -> GameWorld

Hallo,

I am now at the point where I have to start thinking about how to design my game. So far I have just made classes and forced them in between others to see how different functions work. Now I want to take on step back and start designing at all so it makes a bit more sense.

Here is my "outline" so far:

Code:

---

gameWorld
{
        public:
                update();
                draw();

        private:
                TimerFunction();

        // Variables
        private:
                BulletMgr class
                Map class
                EnentyMgr class
}

---

I also have a global (singleton) class for drawing and manging graphics.

The problem is that BulletMgr, Map, and EntetyMgr all need to know about each other(I think?) Is there a neat way to solve this?

Note that you're missing the "class" (or "struct" if you want to be picky) keyword in your example.

Quote:

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EntetyMgr

---

"Entity", perhaps?

The first thing that strikes me is that you could have a Mgr or Sprite class to handle bullets and entities. Perhaps you could inherit from this class to create entity and bullet versions if they're different enough.

And what does your Map class represent? If it decides where entities can go, then the Sprite/whatever class will probably need to know about it somehow.

Is there a neat way to solve this? I don't know. I think maybe you need to provide more information if you can . . . .

I'll describe the method I'm using and you can decide if it suits you. My method is inspired by (what I remember of) quake 3 code.

Your winMain has three entry points for "the game":

// called after window initialization and openGl setup
Game Setup

// called during the main windows loop
Game Loop

// called after the main windows loop during shutdown procedure
Game Shutdown


Your key object that is going to link everything together is your Game State object.
Heres a rough outline of that object

Code:

---

class GameState {
    long currentTick;
    long lastTick;

    std::vector<entity_npc> npcEntites;
    std::vector<entity_player> playerEntities;
    std::vector<entity_projectile> projectileEntities;
    std::vector<entity_emitter> emitterEntities;
    Level * map;
}

---

The method is as follows:
Game Setup:
Initialize your GameState object and all the objects it consists of etc.

Game Loop:
Save the Current GameState as Last GameState.
Do all updates / calculations based on the Last GameState and put the new values
in Current GameState.
Do Rendering based on Current GameState.

Game Shutdown:
Free all your memory / standard shutdown etc.


Pseudo Code Example

Code:

---

GameState lastState;
GameState currentState;

function GameSetup() {
    // first tick
    currentState.currentTick = GetTickCount();
    currentState.prevTick = GetTickCount() - GOAL_TICK_PER_FRAME; // start off with ideal difference
    // load level
    Level map = new Level();
    currentState.map = map;

    // load players
    for(i = 0; i < clients; i++)
          currentState.playerEntities.push_back(new entity_player(client[i]));

    // load npc entities
    for(i = 0; i < npcs; i++)
          currentState.npcEntities.push_back(new entity_npc(npcs[i]));

    // no projectile data yet

    // no particle emitters yet
}
 
function gameLoop() {
    // save currentState as last
    lastState = currentState;
   
    currentState.currentTick = GetTickCount();
    currentState.prevTick = lastState.currentTick();
   
    // update projectile entities
    for(i = 0; i < projectileEntities.size(); i++) {
          currentState.projectileEntities[i].position = lastState.projectileEntities[i].position + lastState.projectileEntities[i].velocity;
    }
    // update player entities
    for(i = 0; i < playerEntities.size(); i++)
          updatePlayerPositionFromInput(playerEntities[i]);

    // update npc entities
    for(i = 0; i < npcEntities.size(); i++)
          updateNpcPositionFromAi(npcEntities[i]);

    // etc

    // now that currentState has been updated we do rendering based on objects in currentState.
    // render map, players, npcs, projectiles, etc.
    // render ui
    // etc.
}

function gameShutdown() {
    // free up memory etc.
}

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Of course, your main game loop wont do any of the actual data updates, i did the projectile stuff in place as an example, but ideally it would be handled similar to player input and npc control in the example. You just pass all the needed info (entity object, entire entity list or even the entire game state object(s)) to your physics, ai, or input systems and let them do the updates.


It will be up to you to decide what objects are included in your game state and decide how you want to manage those objects (this example uses vectors).

Hope this helps you decide on a way to tie everything together.