Author : Jay
Page : 1
This lesson will initialize allegro, set up keyboard support, show an empty screen and wait for a keypress - then quit.
Microsoft Visual C++ Specific
Before you do anything, make sure you linked to the library. Go to Project - Settings - Link Tab: Under "Object/Library modules" go to the end of the line, hit space and type this in: alleg.lib Then hit ok. Now the allegro library is linked to your program
*You must do this with every new program*
Here is your first line. You must include the allegro header file or else nothing will work :)
#include <allegro.h> // You must include the Allegro Header file
Allegro uses the Win32 style application, NOT the console application. Make sure your MAIN always looks like the following. Don't worry if you aren't used to it, soon enough you will memorize this.
int main(int argc, char *argv[])
{
Next, we will initialize allegro. This will set up all the components it needs in order to run. This function basically does all the hard stuff for you.
allegro_init(); // Initialize Allegro
Now that allegro is initialized we will want to set up an input device so the user will be able to control how the program will execute. For this program we want to include support for only the keyboard. This function will set up all keyboard related functions and variables.
install_keyboard(); // Initialize keyboard routines
Ok. Almost everything is set up and ready to roll. There is one more part that needs to be done before we can process any kind of output to the user: setting up the screen.
This next part can be a little tricky, and may take some time to get used to.
set_gfx_mode will set the graphics mode that you will use in your program.
Here is what each paramater is:
set_gfx_mode(GRAPHICS MODE, Width, Height, Virtual Width, Virtual Height);
GFX_AUTODETECT for a graphics mode will set everything for you, using the machine's preinstalled drivers.
The width and the height are simple that, the width and the height of the screen.
The V_Width and V_Height are the virtual (not visible) width and height of the screen.
We don't need to worry about these for the moment, so entering zeros will just create NO virtual screen.
set_gfx_mode(GFX_AUTODETECT, 640,480,0,0); // Change our graphics mode to 640x480
This almost concludes lesson 1. Now the screen will change to the desired resolution. In order to see the effect, we need to stall the program for a moment. This next function simply waits for any keypress from the keyboard - and then will continue through the program
readkey();// Wait untill a key is pressed
After the key is pressed, we must tell the program that everything executed without error and then exit
return(0);// Exit with no errors
}
We are not done yet, however. There is still one more thing that needs to be done. This part is very important. In every allegro program you write, you must include this function. The following function is allegro specific - and your programs will not work unless it is found right after the closing bracket of your main function
END_OF_MAIN(); // This must be called right after the closing bracket of your MAIN function.
// It is Allegro specific.
This concludes Lesson 1. You now know how to set up an allegro environment and change the resolution of the screen. This is an important component in all allegro programs. You will use it in every program in the future.
Lesson 1 code:
/*******************
Allegro Newbie Tutorial
by
LoomSoft
http://loomsoft.cjb.net
*******************/
/**************************************************
LESSON 1 :
Initialize allegro - set up keyboard support -
show an empty screen and wait for a keypress.
The screen will not show anything, it will just
be black.
***************************************************/
/*
Before you do anything, make sure you linked to the library.
Go to Project - Settings - Link Tab:
Under "Object/Library modules"
go to the end of the line, hit space and type this in:
alleg.lib
Then hit ok. Now the allegro library is linked to your program
*You must do this with every new program*
*/
#include <allegro.h> // You must include the Allegro Header file
/*
Allegro uses the Win32 style application, NOT the console application.
Make sure your MAIN always looks like the following.
Don't worry if you aren't used to it, soon enough you will memorize this
*/
int main(int argc, char argv[])
{
allegro_init(); // Initialize Allegro
install_keyboard(); // Initialize keyboard routines
/***************************
set_gfx_mode will set the graphics mode that you will
use in your program.
Here is what each paramater is
set_gfx_mode(GRAPHICS MODE, Width, Height, Virtual Width, Virtual Height);
GFX_AUTODETECT for a graphics mode will set everything for you, using
the machine's preinstalled drivers.
The width and the height are simple that, the width and the height of
the screen.
The V_Width and V_Height are the virtual (not visible) width and height
of the screen. We don't need to worry about these for the moment, so entering
0's will just create NO virtual screen.
****************************/
set_gfx_mode(GFX_AUTODETECT, 640,480,0,0); // Change our graphics mode to 640x480
/********************************************
This function stops the program untill a key
is pressed
********************************************/
readkey();// Wait untill a key is pressed
return(0);// Exit with no errors
}
END_OF_MAIN(); // This must be called right after the closing bracket of your MAIN function.
// It is Allegro specific.
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