Adding non ECS features in an ECS engine (tilemap)?

Steve Hatcher · 2015-05-14T00:17:13

Hello, I have been learning how to use entitiyx to convert my OOP game into an ECS game. I have gotten the basic components working, and created some entities and placed them in the game "world". I am at part where I want to add my tile map in. I have three different tile maps (saved as csv txt files), created in tiled. I have map loading and rendering working in my OOP design but would like some advice on how to get this going in an ECS engine. I have been reading a bit online and there seems to be no general consensus as to how to do this. In my game (a 2d scrolling plane shooter) there will be no interactions with the ground at this stage. So I think I could put my tileMap in pretty much as I have it in the OOP design. It seems to me overly complicated and "expensive" to tag tiles with components. The part I am stuck at is the organization of this code. Right now the games update() and render() functions work as follows: void Game::update() { m_systemManager.update<LevelSystem>(frameTime); m_systemManager.update<PlayerControlSystem>(frameTime); m_systemManager.update<MovementSystem>(frameTime); } void Game::render() { graphics.beginScene(); graphics.spriteBegin(); m_systemManager.update<RenderSystem>(frameTime); m_systemManager.update<MenuSystem>(frameTime); graphics.spriteEnd(); graphics.showBackbuffer(); } The way I got tiles working in my OOP design was by adding the tiles directly to the class which inherits from Game e.g. class TileMapExample : public Game { private: mgeTexture tileTextures; mgeSprite tile; where an mgeSprite has a draw command that goes to my graphics class. So in my old game render loop it would loop through the tiles [row] and [col] calling draw e.g. tile.draw(UINT(tileMap[row][col])); But in my new ECS game design there is nothing to do with actual in game entities in the Game class, that stuff is all taken care off via components and my entitiyCreator. The Game calss is as follows: class Game : public entityx::Receiver<Game> { private: Graphics graphics; GameManager m_gameManager; Input m_keyHandler; HWND hwnd; entityx::EventManager m_eventManager; entityx::EntityManager m_entityManager; entityx::SystemManager m_systemManager; void createSystems(); void update(); void render(); // Frame rate code LARGE_INTEGER timeStart; // Performance Counter start value LARGE_INTEGER timeEnd; // Performance Counter end value LARGE_INTEGER timerFreq; // Performance Counter frequency float frameTime; DWORD sleepTime; float fps; So this is where I ask for some assistance. Do I just cram my tile map stuff into this game Class, and update and render it separately in Game::update() and Game::Render() so e.g. Render() would look like this void Game::render() { graphics.beginScene(); graphics.spriteBegin(); ////////added this stuff for the tile map rendering/////// for(int row=0; row<MAP_HEIGHT; row++) { for(int col=0; col<MAP_WIDTH; col++) { etc etc loop through and draw tiles} ////////added this stuff for the tile map rendering/////// m_systemManager.update<RenderSystem>(frameTime); m_systemManager.update<MenuSystem>(frameTime); graphics.spriteEnd(); graphics.showBackbuffer(); } Or is there a more elegant solution, that somehow still lets me use components and systems but not tagging the tiles as entities? It just seems the tile map render code should go into m_systemManager.update<RenderSystem>(frameTime); which looks as: void RenderSystem::update(entityx::EntityManager &entities, entityx::EventManager &events, double dt) { Position::Handle position; Display::Handle display; for (entityx::Entity entity : entities.entities_with_components(position, display)) { spriteData.setTextureRect(display->coord); spriteData.setPosition(position->position); m_graphics->drawSprite(spriteData); } } But if I had my tile drawing here and didn't have my tiles as entities..., I cant figure out how I would pass in all the tile information in, since it gets sprite info from entities which I have given position and display components. Thanks for any input.

For Beginners

Started by SteveHatcher May 03, 2015 06:20 AM

11 comments, last by TheChubu 8 years, 11 months ago

SteveHatcher

1,237

Author

May 09, 2015 12:38 PM

Thanks for the discussion guys, took me a while to get my head around these replies hence the late post...

@haegarr

Your post makes a lot of sense, thanks for taking the time to write that.

"So, question is to which layer(s) do Game::render and RenderSystem::update belong to?"
Game::render() is called from game::run() so yes I guess it is the top level of rendering.

"If "sprite" is your graphic primitive of choice for both ground and entities, then you will have a ground renderer and an entity renderer in the end, the first using a ground representation as input and the latter using game objects as input, and both yielding in sprites as output."

I think this is where I am confused.

I don't fully understand how Game::render works on scene objects (are objects things in game that *Do* stuff eg my player spaceship and enemy ship..?) Is the way I currently have it? Where by it calls m_systemManager.update<RenderSystem>(frameTime) correct..?

"It may iterate all drawables in the scene and invoke their render() method. That render() methods will be the second layer of rendering and perhaps already output the sprite primitives."
Can you give me an example of what you mean by this?

"and RenderSystem::update(time) should not exists as such."

Thanks I have removed that. I understand that the logic updates need a delay time to work out the correct movements, but for some reason thought the renderer did it, but I forgot that the game engine will be kept at my chosen fps, and therefore it will not matter if I pass in the time.

@CRYP7IK

Are you saying basically label nothing as an actual entity, but just use components and systems to do the work? In this case I can't understand how to get the data into systems? Because so far I only understand the method of "for (entityx::Entity entity : entities.entities_with_components(component1,component2,etc))" for actually getting the entity data into systems...

@L. Spiro

I understand what you're saying and agree. If I had read that post before going down this route I would have stuck with how I was doing it, but I have spent months getting this working and now I feel if I turn back it does me more harm than good... either way I have learnt a lot so I feel it was not entirely a waste.

@ferrous
haha thanks

@SOL-2517
So rather than my old engine where a TILE was essentially a sprite that had a tile.draw() function, I will pass the data to a renderer that has something like drawTile(tile[1][2])? The other thing I am a bit stuck with was in the old approach I would put the tiles where they need to go using tile.setX(), tile.setY(), which updated the underlying spriteData structure which was sent to directXTK to draw. This way, if tiles are plain old data, how do I specify these additional needs, such as tile position X and Y.

Thanks all

nhold

1,336

May 13, 2015 11:18 PM

@CRYP7IK

Are you saying basically label nothing as an actual entity, but just use components and systems to do the work? In this case I can't understand how to get the data into systems? Because so far I only understand the method of "for (entityx::Entity entity : entities.entities_with_components(component1,component2,etc))" for actually getting the entity data into systems...

No, you would put TileMapRenderer and TileMapSettings onto an entity (This might set the bottom left of the TileMap to that entities position or something) and assign the TIleMapRenderers TileMap to some data.

Engineering Manager at Deloitte Australia

TheChubu

9,484

May 14, 2015 12:17 AM

You could always have a TileMapSystem that manages the tiles of the map. You could model these as entities or simply "renderables" that are passed to a renderer inside that system.

I do it in a deferred way as in when you pass something to the renderer, it doesn't draws it right away, just adds it to a queue. Then after each system passed all the renderables they're in charge of processing, a "RenderSystem" does the actual rendering.

Off the top of my head, if you want to model everything as entities:

You could have something like the TileMapSystem being in charge of loading up a map and then construct entities from the tiles.

Then you'd have different systems (StaticTileSystem, DynamicTileSystem, AnimatedTileSystem, etc) that pick up and process these entities (for dynamic, they can move, for both static and dynamic they can get culled, etc) and send them to the renderer.

RenderSystem would grab the queue that the rest of the systems built before and render it. This means you have a strict ordering in your system update chain, but that's okay, those dependencies are well defined that way and you can easily visualize how the entire game is run.

"I AM ZE EMPRAH OPENGL 3.3 THE CORE, I DEMAND FROM THEE ZE SHADERZ AND MATRIXEZ"

My journals: dustArtemis ECS framework and Making a Terrain Generator

Adding non ECS features in an ECS engine (tilemap)?

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