function definition(?) problem

[Draco]

I have a function that will either not enter or not complete correctly. Since I am using allegro and it takes control of the screen I havent been able to debug to see what's wrong. I have tried everything, and my function call seems fine the way it is. Hopefully someone can see what is wrong. I'll just include the function and the call, but if anyone wants the entire file I'll post the project file.

//structures used

struct person{
	int x,y;					//point coords
	int width, height;			//sprite dimensions
	float x_vel, y_vel;			//velocities
	int alive;					//alive, dead, or dying
	int direction;				//facing left or right
	BITMAP *sprite;				//pointer to current sprite
};

struct bullet{
	int x,y;					//point coords
	int width, height;			//sprite dimensions
	float vel;					//velocity for x-dimension
	bool exists;				//is bullet fired or not
	int num_bullets;			//number of bullets in array, to help functions
};

//function

bool fire_bullet(struct person *shooter,struct bullet ammo[])
{
	int count=0;
	for(count=0;count < ammo->num_bullets;count++)
	{
		if(ammo[count].exists == false)
		{
			ammo[count].exists=true;
			if(shooter->direction == LEFT)
			{
				ammo[count].x=shooter->x;
				ammo[count].vel= -BULLET_VEL;
			}
			else
			{
				ammo[count].x=shooter->x + shooter->width;
				ammo[count].vel=BULLET_VEL;
			}
			ammo[count].y=shooter->y;
			return true;
		}
	}
	return false;
}
END_OF_FUNCTION(fire_bullet);

//function call

if(key[KEY_ENTER])
     fire_bullet(&player,player_bullets);

[Salem]

> int num_bullets;
Why do you store this for every bullet, when only ammo[0].num_bullets appears to be valid (or used)

> return true;
1. true/false/bool are not C
2. you didn't increment the number of bullets

> if(ammo[count].exists == false)
Using boolean logic is more readable IMO
if( !ammo[count].exists )

[Draco]

Thanks for pointing that out salem. I switched the loop control line to

for(count=0;count < ammo[count].num_bullets;count++)

but it still doesnt work, although I know its more correct now. As for your second point, I forgot that is C++ only, but I think I'll use it anyway since MSVC automatically makes files C++. I may decide to try doing this with classes sometime in the future.

[Salem]

> but it still doesnt work, although I know its more correct now
How so?
Every time you change the number of bullets, you have to go through all the other bullets, changing the number of bullets.
There's no reason for storing this wilth every single bullet!

struct ammo {
    int num_bullets;
    struct bullet *bullets;
};

[Draco]

I got it to work. thanks.

[Draco]

I'm running into another problem now. The firing function works, but I can only fire the bullets once and then it doesnt work. I'll add on the updating function for the bullets. Again, I looked at it and everything seems fine to me.

struct ammunition{
	int num_bullets;			//number of bullets in array, to help functions
	struct bullet *bullets;		//pointer to bullet array
};

bool fire_bullet(struct person *shooter,struct ammunition ammo)
{
	int count=0;
	for(count=0;count < ammo.num_bullets;count++)
	{
		if(ammo.bullets[count].exists == false)
		{
			ammo.bullets[count].exists=true;
			if(shooter->direction == LEFT)
			{
				ammo.bullets[count].x=shooter->x;
				ammo.bullets[count].vel= -BULLET_VEL;
			}
			else
			{
				ammo.bullets[count].x=shooter->x + shooter->width;
				ammo.bullets[count].vel=BULLET_VEL;
			}
			ammo.bullets[count].y=shooter->y;
			return true;
		}
	}
	return false;
}
END_OF_FUNCTION(fire_bullet);

void update_bullets(void)
{
	int counter=0;

	for(counter=0;counter < PBULLETS;counter++)
	{
		if(player_bullets[counter].exists == true)
		                if(0 < player_bullets[counter].x < screen_width)
			{
				player_bullets[counter].x += player_bullets[counter].vel;
			}
			else
			{
				player_bullets[counter].exists=false;
			}
	}

	counter=0;

	for(counter=0;counter < EBULLETS;counter++)
	{
		if(enemy_bullets[counter].exists == true)
			if(0 < enemy_bullets[counter].x < screen_width)
			{
				enemy_bullets[counter].x += enemy_bullets[counter].vel;
			}
			else
			{
				enemy_bullets[counter].exists=false;
			}
	}
}
END_OF_FUNCTION(update_bullets);

[Salem]

So where do you ever change
ammo.num_bullets

?

[Draco]

#define PBULLETS 8

struct bullet player_bullets[PBULLETS];

ammunition playerammo={PBULLETS,player_bullets};

I meant to post those last time.

[Draco]

I did some working and figured out the problem is in the updating function. I redid it to use the ammunition structure, and turned it into an int for testing purposes. The else portion of the if/else never happens when the bullets go out of the screen coordinates. I can't see whats wrong with it.

int update_bullets(struct ammunition ammo)
{
	int counter=0;

	for(counter=0;counter < ammo.num_bullets;counter++)
	{
		if(ammo.bullets[counter].exists == true)
			if(0 < ammo.bullets[counter].x < screen_width)
			{
				ammo.bullets[counter].x += player_bullets[counter].vel;
			}
			else
			{
				ammo.bullets[counter].exists=false;
				return 1;
			}
	}return 0;
}
END_OF_FUNCTION(update_bullets);

[itsme86]

I just have to ask...what does your END_OF_FUNCTION() macro do?

[Draco]

It's a requirement when using the Allegro API. I dont remember exactly what it does with the macros.