Hi!
I'm quite new to Allegro 5 and programming in general. I've watched those tutorials:
http://fixbyproximity.com/2d-game-development-course/
http://fixbyproximity.com/oop-game-development/
and they're the main source of my knowledge.

In "Globals.h" which is included by everything, I have
static ALLEGRO_DISPLAY *display=NULL;
The display is initialized later in "main.cpp".
Everything with the display has been working fine, the game's running. The only problem is this:
My class "Player" has a function Player::Render(). It's worked before, but when I try to draw something to display, or use al_get_backbuffer(display); the following happens:
The code compiles, but when I run it I instantaneously get an exception looking like I'm trying to delete something that's already deleted, etc. (at least that's what I read on the internet)
It's similar to this one: Unhandled exception at 0x0F1FE0C4 (allegro-5.0.10-monolith-mt.dll) in TEST.exe: 0xC0000005: Access violation reading location 0x00000008. but the numbers vary.

It's happened in two different places and right now I just moved those troublesome drawing sequences into the main, next to the place where Render() would be called. But it's really annoying and my code will soon get messy if I don't know how to handle this.

Please, help me!
Cheers

But using 'static' compiles? I thought it would give redefinition errors. :/

Yeah, to make a variable globally visible you use the extern keyword.

You declare it once in your header as extern :

header.h

#ifndef HEADER_H
#define HEADER_H

extern ALLEGRO_DISPLAY* display;

#endif // HEADER_H

And then define it once in one source module somewhere.

module.cpp

#include "header.h"

ALLEGRO_DISPLAY* display = 0;

No, you just do it once for each header that you have. It prevents it from being accidentally included twice, which would cause errors.

You haven't checked any return values. Your fonts and bitmaps might not always load properly, and you have to check for that yourself. Is HealthBar a valid bitmap that has been created somewhere else?

Show more code after you check the return values if you're still having a problem.

Either pass the font as a parameter to the function, or make the font global like you just did with 'display'.

To beoran:
So do I understand correctly that I would like to use my_create_display only once, in main, after initializating allegro?
And then use my_get_display() everytime I would normally use display?

I'll check if the suggestions from both of you work in a minute. Thanks!

EDIT:
Ok, so here's my not working FloorGenerator::Update()

display.h:

display.cpp:

FloorGenerator.h:

Then we have FloorGenerator.cpp, with a function Update() which causes the unhandled exception. I don't load any fonts or samples, so it's not where the problem is.

I just want to mention, that the exact same code put in main worked, of course if I created the floorMap in main too.

What's the cause of the problem? My other problem is in the Player::Render() but it's probably caused by a similar thing. I will get to that once we deal with that.

Cheers

Oh man, I have absolutely no idea what those threads mean and what they do.

But I have the following project settings:

http://s17.postimg.org/y3watnzfj/Bez_tytu_u.png

I use them because now I can use Advanced Installer to make an installer for my game. I learnt that from the following tutorial: https://www.youtube.com/watch?v=Ny-rsCSYkzU
This guy said those project settings are needed. And I don't wanna have a game that I can't give my friends easily.
I really can't use the display conveniently in my class member functions without changing those settings?
Cheers

Oh yeah, sure. That'd be great.
I attached the zip file to this post.
Cheers

You do not want to be using static variables in a header. If you need to share variables between source modules then you need to declare them as 'extern' and define them in ONE source file w/o the extern on the definition.

my_header.h

extern int setting;

my_source.cpp

#include "my_header.h"

int setting = 0;

http://en.wikipedia.org/wiki/Static_%28keyword%29

To show you why, here is a little demo code :

globals.h

#ifndef globals_HPP
#define globals_HPP

#include <cstdio>

struct ALLEGRO_DISPLAY;

static ALLEGRO_DISPLAY* display = 0;

void mod2();

#endif // globals_HPP

module1.cpp

module2.cpp

#include "globals.h"


void mod2() {
   printf("Module 2 says address of display is %p\n" , &display);
}

Output of program :

c:\ctwoplus\progcode\allegro5\test\statictest>statictest.exe
Main says address of display is 00407020
Module 2 says address of display is 00407024

So each module is getting its own copy of each variable declared as static. That's not what you want. You want one instance of each variable shared among modules, and that's what extern is for.

Also, there were a ton of warnings compiling your code. I understand it is still in development but you should enable warnings and remove as many of them as you can.

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