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Game structure help (libgdx)

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#1 pkash16   Members   -  Reputation: 126

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Posted 23 July 2014 - 01:49 PM

I am currently about to start work on a libgdx game. All my previous libgdx games were messy and all over the place, and I ended up getting lost in my code. I know HOW to play music, draw to the screen, get input, etc., but not how to put it all together in a neat way. 

 

In my past game I had used oop to make a game where every object was an Entity, and then I made a hierarchy - this is an example:

Entity -> VisibleEntity -> Enemy -> RandomTestEnemy

VisibleEntity contained a position,velocity an image file, as well as a render method.

 

This is obviously not the right way to do things, or atleast thats what i've been told. I read online that you need to keep classes simple and have a simple purpose. So, I would need to make a class that solely renders things to the screen, or solely handles input, not throw it all into one class. This makes sense, but I don't really follow how to go about doing it.For a simple game like all my previous projects, something like the above worked. However, I want to move on to bigger projects. For this, I need to find a way to put it all together. 

 

With libgdx, I create a class that extends Game, which is one of libgdx's 2d library classes. With it, I can use the setScreen method to set the screen to different screens whenever I want. In the end, I would end up with 6 screens or so, including a settings screen, a level select screen, etc. The problem is what to do with the code in each screen. Do I handle input in each individual screen class? Or does it suffice to make a class called 'inputhandler' or something and then handle all input there? Furthermore, if I make a class called 'RobotEnemy' or something to that nature, do I put a render method in that class, or make an EntityRenderer class and render entities such as RobotEnemy through that way? What do I put in my "Screen" class? 

 

In any case, I am confused. I know that there is no "right" way to do this, but I would like someone to point me in the right direction.

 

Any thoughts/links to good webistes/books?



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#2 Glass_Knife   Moderators   -  Reputation: 4084

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Posted 23 July 2014 - 02:43 PM

http://www.gamedev.net/page/resources/_/technical/game-programming/implementing-component-entity-systems-r3382

 

I thought I saw an article about just this thing.  

 

Now, having said that, I will offer another suggestion.  Test your code.  If you have unit tests for all the code (that you can test), then you have the freedom to refactor stuff when it gets messy without breaking stuff.  Writing tests are no fun, so when we're working on a game, we don't do that.  Because tests are for business software, not games, right? But tests will let you keep cleaning up the code without breaking stuff.  If you apply the red/green/refactor approach, always cleaning up code that is messy, you can let the design evolve from the code you have instead of trying to guess at what you need (which never works anyway).


I think, therefore I am. I think? - "George Carlin"
Indie Game Programming

#3 pkash16   Members   -  Reputation: 126

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Posted 23 July 2014 - 07:22 PM

thanks for the link!

Now, on to unit testing: I hate doing them. But as always, they are a necessary evil. Never really thought of implementing them in game dev, though. Thanks for the insight!



#4 Glass_Knife   Moderators   -  Reputation: 4084

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Posted 25 July 2014 - 07:44 AM

No one likes testing.  But you don't have to test everything if you're making a game.  Just add tests to the code when you break something.  It goes something like this:

 

Developer Journal:

 

Saturday morning.  I've been playing the game, and everything seems good.  But I did notice that when the plant monster explodes from the bombs, it doesn't look very good.  I think I should clean that up.

 ~  

O.K.  That was a nightmare.  It turned out that there wasn't a good way to tweak the parameters of the explosions.  So I added a script that can be loaded with parameter values and reloaded at run-time with a hot key.  Now everything is broken.  I didn't even put in the script yet, and there isn't any code in there that should do anything, but everything is broken.  Programming is stupid.  I think I'll take a nap.

~

Saturday night.  It turned out that the resource loaded was overwriting the resource references when the scripting engine started up.  Stupid pointers.  But instead of just fixing the problem, I will add a test case that breaks because of the bug.  Then I will know it is fixed and won't happen again.

~

GAHHHH!!!!  There was no way to test the resource references bug.  Everything was hidden inside.  While trying to refactor to expose the code to test, I broke some more stuff.  Why is this so hard?

~

I'm better now.  The code is refactored.  I added tests for all the stuff that was broken, and I found a nasty bug in the process that would have taken forever to fix later.  Time to play vvvvvv...

 

You don't need to test drive your code.  And you don't need to test everything.  But when you find a weird bug, add in some automated tests to make sure it doesn't break in the future.  You'll be surprised at the feeling you get knowing that everything is working.


Edited by Glass_Knife, 25 July 2014 - 07:46 AM.

I think, therefore I am. I think? - "George Carlin"
Indie Game Programming





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