float to int issue <solved>

[ArchAngel777]

I have a mana draining function that drains mana based on percentage of the damage dealt.

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void A_CustomMeleeAttack2(int damage = 0, sound meleesound = "", sound misssound = "", name damagetype = "none", bool bleed = true)
	{
	// call original function
	A_CustomMeleeAttack(damage, meleesound, misssound, damagetype, bleed);
	
	// perform Mana drain
	if (CheckMeleeRange(-1))
		{
		A_TakeFromTarget("Mana1", (int)(floor(damage/2)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		A_TakeFromTarget("Mana2", (int)(floor(damage/3)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		A_TakeFromTarget("Mana3new", (int)(floor(damage/4)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		health += damage;
		//if (health > SpawnHealth() ) { health = SpawnHealth(); }
		}
	}

The problem is, converting the float coming from the division of damage into an int, isn't working as expected. So, the mana1 drain seems to work just fine, no issues. But the mana2 and mana3 draining will often result in a sudden set to 0. For example, I may have 160 mana2, than it suddenly becomes 0. I assume some kind of data type issue is occurring. If anyone has any ideas, I'd really appreciate it. I can have all 3 mana types drain by damage/2 and that works fine, but I wanted the stronger mana types to drain at a lower percentage for balancing reasons.

[MartinHowe]

I'm not sure what the floor function is for here - damage is an int, so are 2 and 3; so the result should be an int anyway, and it will be truncated towards zero. So (int)(floor(X/Y))if X and Y are both int is like:

1) Divide X by Y, giving Z, where Z is an int.
2) Promote Z to double. It will have a zero fractional part.
3) Use floor to remove the (non-existent) fractional part of Z, giving ZZ, which is double.
4) Round down (truncate) ZZ to int.

You might as well just divide damage by 2 (or 3) directly and have done with it. I'd say try it and then see what happens.

(Although not necessary here, if you actually did want to get a double from the division so that there is a fractional part, using 3.0 instead of 3 should do it; this is why a lot of the inbuilt code is littered with integers suffixed by a decimal point so as to make them double literals instead of ints).

[ArchAngel777]

Well my first attempt was just "damage/4" which caused the same issue. I than tried "round(damage/4)" and than finally "(int)(damage/4)" until I ran out of ideas. Either case, the result is the same. When dividing by any number other than 2, it will occasionally set mana to 0. Not only that, but /3 or /4 will also sometimes result in losing way MORE mana than /2. The wiki says all rounding functions return a float, and casting doesn't seem to solve the issue, so I am fresh out of ideas now. I also tried "damage/4.0" and every combination of all these approaches.

If I can't figure this out, I'm thinking I'll have to do something hacky, like randomly drain one type of mana, but with a higher chance of draining mana1 versus the other mana types.

[MartinHowe]

Hmm. Have you tried putting logging statements in the function so you can see exactly what damage is coming in in the first place: ALogInt(damage);? Or even finding how much damage was actually caused?

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void A_CustomMeleeAttack2(int damage = 0, sound meleesound = "", sound misssound = "", name damagetype = "none", bool bleed = true)
	{
	// Get  Health of target before the attack
	int oldHealth = target.Health;
	
	// call original function
	A_CustomMeleeAttack(damage, meleesound, misssound, damagetype, bleed);

	// Get actual damage dealt
	int actualDamage = oldHealth - target.Health;
	A_LogInt(actualDamage);
	
	// perform Mana drain
	if (CheckMeleeRange(-1))
		{
		A_TakeFromTarget("Mana1", (int)(floor(damage/2)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		A_TakeFromTarget("Mana2", (int)(floor(damage/3)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		A_TakeFromTarget("Mana3new", (int)(floor(damage/4)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		health += damage;
		//if (health > SpawnHealth() ) { health = SpawnHealth(); }
		}
	}

[ArchAngel777]

The damage, actualDamage and the (damage/4) all log the expected values. So perhaps the issue is with the A_TakeFromTarget() function?

[Jarewill]

If the amount parameters in A_TakeFromTarget is set to 0, it will take away all items instead of none, which is what I'd guess is happening here.
Try adding checks to see if the amount isn't equal to 0 first before taking away:

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If((int)(floor(damage/2))!=0){A_TakeFromTarget("Mana1", (int)(floor(damage/2)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);}
If((int)(floor(damage/3))!=0){A_TakeFromTarget("Mana2", (int)(floor(damage/3)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);}
If((int)(floor(damage/4))!=0){A_TakeFromTarget("Mana3new", (int)(floor(damage/4)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);}

[randi]

I would like to point out that there are no floats here, until one is created with floor().

damage is an int:

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void A_CustomMeleeAttack2(int damage = 0, sound meleesound = "", sound misssound = "", name damagetype = "none", bool bleed = true)

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		A_TakeFromTarget("Mana1", (int)(floor(damage/2)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		A_TakeFromTarget("Mana2", (int)(floor(damage/3)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);
		A_TakeFromTarget("Mana3new", (int)(floor(damage/4)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);

damage/2, damage/3, and damage/4 are all integer divisions. After division, they are promoted to floats to pass to floor() (which won't do anything because ints have no fractional part), then they get converted back to ints. In other words, here (int)(floor(damage/2)) is the same as damage/2 with extra work.

(Or what MartinHowe explained in detail above, but it doesn't seem to have been heeded in subsequent posts. Jarewill has the correct answer, although it still has the whole (int)floor(int) thing going on.)

This would probably be a good case for another flag for A_TakeFromTarget().

[ArchAngel777]

If the amount parameters in A_TakeFromTarget is set to 0, it will take away all items instead of none, which is what I'd guess is happening here.
Try adding checks to see if the amount isn't equal to 0 first before taking away:

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If((int)(floor(damage/2))!=0){A_TakeFromTarget("Mana1", (int)(floor(damage/2)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);}
If((int)(floor(damage/3))!=0){A_TakeFromTarget("Mana2", (int)(floor(damage/3)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);}
If((int)(floor(damage/4))!=0){A_TakeFromTarget("Mana3new", (int)(floor(damage/4)), TIF_NOTAKEINFINITE, AAPTR_DEFAULT);}

ahh that was it. I wasn't aware of that being the case. I did see something like that mentioned in the wiki but at first glance I wasn't quite sure what it meant. Thanks for the help!