11 replies to this topic

[Rei_NERV]

Why won't this return true?

bool Bullet::bullethit(Image b)

{

	if((centerx > b.left && centerx < b.right) && (centery > b.top && centery < b.bottom))

		return true;

	else

		return false;

}

[BuckAMayzing]

If this is supposed to be a normal (x,y) coordinate type, then your inequalities are backwards. (centery > b.top) means that the center is ABOVE the top. (centery < b.bottom) means that it's BELOW the bottom. It's quite impossible for it to be both simultaneously. Just flip all of the signs around and you should be fine.

[Rei_NERV]

The x,y coordinates are in allegro, and in allegro, the higher you go, the smaller the y gets.
Think of it as, x = 0; y = 0; are the coordinates of the top left corner of the screen.

[julmuri]

Thats weird, the code looks right.
You should try to breakpoint the function and see the values.
My best guess is that you are passing a wrong image in to the function.

[kmhosny]

may be you need equality in this conditions ,
(centerx >= b.left && centerx <= b.right)

[Rei_NERV]

Equality didn't do the trick.
And unfortunately, I am passing the right image to the function. I wish it was wrong :P

[BuckAMayzing]

Check the values of centerx and centery during runtime. Perhaps they're not initializing correctly.

[Rei_NERV]

They are updating correctly. Which probably means that they initialize correctly, right?

[kmhosny]

well this is a weird code :), make sure that you didnt swap the centerx.left and right so the condition may not become valid.

[BuckAMayzing]

Rei_NERV said:

They are updating correctly. Which probably means that they initialize correctly, right?

Yep, that would probably mean that. Have you tried stepping into the if statement with a debugger to find out exactly what's going on here?

Alternatively, some more code would be helpful, something we can execute to test it.

[zoranh]

Is Image custom type that you coded? If so, then did you check left, right, top and bottom fields as they may be calculated wrong?

[Guest]

When I'm at a loss, I can sometimes easily debug my code by printing out the values of some variables. I have applied the concept to your code, it may help. Note that %d may have to be changed to %f or something else depending on your variable type.

bool Bullet::bullethit(Image b)
{
	printf("centerx=%d, b.left=%d, b.right=%d\n", centerx, b.left, b.right); 
	printf("centery=%d, b.top=%d, b.bottom=%d\n", centery, b.top, b.bottom);
	if((centerx > b.left && centerx < b.right) && (centery > b.top && centery < b.bottom))
		return true;
	else
		return false;
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