Allegro Game library

[Firecore]

Anyone here familiar with the allegro game library?

I have some code that does not work:

//This is a small test for allegro

#include <allegro.h>

#define WHITE makecol(255, 255, 255)
BITMAP *img;
char filename[50] = "D:\\clown.bmp";
int x, y;
char buffer[255];

int main()
{
	allegro_init();
	install_keyboard();
	install_mouse();
	set_gfx_mode(GFX_AUTODETECT_FULLSCREEN, 800, 600, 0, 0);
	textout_ex(screen, font, "This is a test", 0, 0, WHITE, 0);
	
	uszprintf(buffer, sizeof(buffer), "Resolution is = %dx%d", SCREEN_W, SCREEN_H);

	//load the sprite
	img = load_bitmap(filename, NULL);


//	set_mouse_sprite(img);
//	show_mouse(img);
//
	textout_ex(screen, font, buffer, 0, 24, WHITE, 0); 
	
	//declare pos of sprite
	x = SCREEN_W / 2 - 1;
	y = SCREEN_H / 2 - 1;




	//main loop
	while(!key[KEY_ESC])
	{
		draw_sprite(screen, img, x, y);//note that the x and y as pos

		//check for arrow key
		if(key[KEY_D])
		{
			if(x > SCREEN_W)
			{
				x = SCREEN_W - 1;
				
				uszprintf(buffer, sizeof(buffer), "The x = %d, and the y = %d", x, y);

				textout_ex(screen, font, buffer, 200, 157, WHITE, 0);
				textout_ex(screen, font, "Tried 2 leave window", 200, 150, WHITE, 0);
			}

			x = x + 1;
		}
	}
	
	destroy_bitmap(img);
	
	allegro_exit();

	return 0;
}
END_OF_MAIN()

Basically, what im trying to do here is to have a 32 x 32 bitmap and put it on the screen and move it when the user presses the 'D' button.

[Firecore]

anyone?
I really need 2 finish my game

[Savage]

anyone?
I really need 2 finish my game

I'm not familiar, but can you tell me what the problem is?Perhaps we will be able to figure it out.

Is the problem that it doesn't move the image?

Savage

[Studlyami]

Yeah its a great library, but I havn't used it in a while. I'm not seeing any obvious errors. What problems are you having? All my allegro code is at home so i can't compare it when do you need this done by?

[Firecore]

Yeah its a great library, but I havn't used it in a while. I'm not seeing any obvious errors. What problems are you having? All my allegro code is at home so i can't compare it when do you need this done by?

What happens is that when I press 'D', instead of going only 1 pixel to the right, it goes straight off the screen at an x of 791 or something like that.

[Firecore]

Also, when I press d, it makes a trail of the image.

[Studlyami]

The trail is because you never erased the old image. You could just put a black square over it, but i remember there being a function that erases the bitmap. Ill have to check that when i get home tonight. After you capture the 'D' you need to put something up that delays the reading of the key press.

After you fix those minor problems the bitmap is going to flicker, you will need to look up double buffering or again i can give you small code sample after i get home from work.

Another suggestion that i should make is


if(x > SCREEN_W)
x = SCREEN_W - 1;

i would change to see if you can move X if so move it if not do nothing

if ((X + bitmap_width)<S CREEN_W)
x++; //move X position
else
//do nothing

[Firecore]

i see.
When u find out, can u tell me what the function is to erase the sprite?

[Studlyami]

Yeah ill put it up after i get home from work.

[Studlyami]

I was wrong there isn't an erase sprite function for the screen. The easy way (for what you are trying to do) is to just erase the bitmap by using the rect fill function. then redrawing the bitmap using the new location. Later when you learn double buffering and using background images you will see how to keep your background.

[Firecore]

I was wrong there isn't an erase sprite function for the screen. The easy way (for what you are trying to do) is to just erase the bitmap by using the rect fill function. then redrawing the bitmap using the new location. Later when you learn double buffering and using background images you will see how to keep your background.

I see. I just found a book on Allegro actually.
It took a bit of searching.
Its really good. The name is Game Programming all in one, third edition by Jonathan S. Harbour.

The next chapter after the one I am reading is all about double buffering.