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OO Game Design


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#1 mmcconnell   Members   -  Reputation: 122

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Posted 26 November 1999 - 07:15 PM

I'm looking for some suggestions on Object Oriented game design. I'm new to C++ so this might seem like a simple question. I've got a DrawManager class that wraps DirectX, I've also got a Sprite Class. Here's the problem. I want my sprite class to be able to draw itself sprite->Draw(). The main game also needs access to the DrawManager to display things like score. How do I let the sprite class have access to the DrawManager?

Marcus


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#2 CJ   Members   -  Reputation: 122

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Posted 23 November 1999 - 10:25 AM

I wouldn't say that is a OO problem.

You should just pass the right parameters (ie, the surface) to the function which draws the sprite.....

That's what I would do

------------------
Dance with me......


#3 ghowland   Members   -  Reputation: 134

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Posted 23 November 1999 - 11:20 AM

The way I handled this was by splitting it into a bunch of layers:

1 - DirectDraw. Just blits in DX and inits DX.
2 - Blitting. Abstraction for blitting, so its API/OS independent.
3 - Draw Queue. Makes a queue that can add/clear list of things to draw. Can draw images, text, animations, etc.
4 - Elements, like sprites and text. These can each have things like sprite->Draw(). text->Draw(). Which will create an index in the DrawQueue...

-Geoff


#4 Phillip Schuster   Members   -  Reputation: 122

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Posted 23 November 1999 - 11:39 AM

Hi !

Well, some people will tell me I am stupid, but I would create a global instance of class DrawManager.
Define this global variable somewhere in your main.cpp or winmain.cpp or something like that like so:

DrawManager MyDrawManager;

In your main.h or winmain.h or something like that put in a:

extern DrawManager MyDrawManager;

Well, that's all. Now you have access to MyDrawManager from everywhere in your program (you will have to include main.h into the implementation file of sprite. Then you could do something like that:

.....
#include "main.h"

void Sprite: raw(long x, long y)
{
MyDrawManager.DrawSprite(this,x,y);
}

Too many global variables are shit, but a few of them are great, cause you have access to them everywhere without casting pointers around all over the time. Pointers are dangerous cause they cause a GPF when they are NULL, and checking them all the time is shit, too !!

Hope this helps.

Phillip


#5 Xai   Crossbones+   -  Reputation: 1358

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Posted 25 November 1999 - 01:25 AM

There are many ways to skin this cat. I am using a similar system in my Project at work: I have touch screen buttons, animating images, updating text areas, etc....all making up my game screen...and each able to change at any time. So what I have is an abstract base class (Image) which contains the Redraw() method. During initialization I add each the screen elements to a list of Image pointers (in addition to the other LOGICAL places it needs to be), then each frame (as called by a timer) I traverse the list calling the Redraw() function for each element. Each element's class can implement the ability to only actually blit if the image has changed...but beware, if you double(triple) buffer they need to set a conuter when they change...and decrament it each flip...so they can get the new version onto each buffer.

Now you see that the Instantiating classes needs to know details of the DisplayManager (like what buffering, unless you blit all of them EVERY frame)...so I recommend one of the following....global variable or static class memeber (IF you do not intend to support multiple monitor or video card setups)..otherwise you might need to pass the DisplayManager to each of the redraw functions...this way additional monitors can be added by just making TWO seperate Image lists...each one associated with a particular DisplayManager.

I could send you source or look at your source if you'd like.


#6 Anonymous Poster_Anonymous Poster_*   Guests   -  Reputation:

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Posted 25 November 1999 - 03:50 PM

What yo are asking is basicaly how to use classes, if yo need another class to access variables in another one jus go like this:

class Game {
int score;
public:
int Give_Score(){return score;}
void Change_Score(int score1){score=score1;}
};

Then if yo need to print score jus do :
printf("WHATEVER:%s",Game.Give_Score());

and yo no how to change score

I think thatl work


#7 Splat   Members   -  Reputation: 122

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Posted 25 November 1999 - 04:27 PM

Esap1: First, your use of English made that posting a little cryptic, but the question is not how to use classes but a specific problem that, unfortunately, has nothing really to do with access control functions in a class. What you described is in fact a solution to a common problem with classes (controlled access to almost-public variables) but is not the problem we are dealing with here.

- Splat


#8 Anonymous Poster_Anonymous Poster_*   Guests   -  Reputation:

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Posted 26 November 1999 - 07:15 PM

Sorry Splat if I did not fully understand the question, and also, I really dont think that I write very bad . I have to admit, Im no teacher But I do have experience in programming games and made a few and must of just mis understood his question, as I am new to DX. sorry.




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