Proc Chance Code

[trevius]

EDIT: Created a new thread for the Proc Chance discussion and moved them into this thread

I had a level 71 bard song directly from the EQLive spell list that was supposed to increase the proc rate for bard songs by only 102%, which to me means it should only be making proc rate slightly more than double what it currently is. But, this song was making bards proc almost every swing, which was extremely overpowered. I had to reduce the proc rate setting down to like 5% to get it under control.

Jonthan's Mightful Caretaker  	BRD/71	1: Increase Attack Speed by 70%
2: Increase All Skills Damage Modifier by 6%
4: Increase ATK by 16 (L71) to 18 (L80)
7: Increase All Skills Minimum Damage Modifier by 204%
8: Increase Proc Modifier by 102%

I can only imagine that instead of multiplying these percentage increases by X amount and then dividing by 100, it is multiplying by X amount and then not dividing at all lol. So instead of evasive increasing avoidance by 50%, it is multiplying it by 50 so you avoid 50X more often, which means you get hit maybe 2% or the time or less. And that is almost exactly what I saw from watching this evasive bug.

Hmm, maybe I can look into the source of it and just add a / 100 to the end of the calculation if I can find it. That may correct many other issues where certain things aren't balanced properly. Though, I imagine AndMetal would probably be better at finding what is going wrong here considering all of his spell and AA work lately. But, if I can find it, I think it should be a simple solution. Of course then I will need to adjust the spell values back to what they were by default to match it up with the new correction.

[trevius]

This may be where the bard song I mentioned is adding the bonus:

			case SE_ProcChance:
			{
#ifdef SPELL_EFFECT_SPAM
				snprintf(effect_desc, _EDLEN, "Proc Chance: +%+i%%", effect_value);
#endif
				// handled with bonuses
				break;
			}

[AndMetal]

Here's where it's calculated w/ the bonuses (zone/bonuses.cpp):
around line 857

                        case SE_ProcChance:
                        {
                                //multiplier is to be compatible with item effects
                                //watching for overflow too
                                effect_value = effect_value<3000? effect_value * 10 : 30000;
                                if(newbon->ProcChance < effect_value)
                                        newbon->ProcChance = effect_value;
                                break;
                        }

Now, as far as ProcBonus, it ends up being calculated in the attack code also:
zone/attack.cpp, around line 3664 (in Mob::GetProcChances)

	ProcBonus += float(itembonuses.ProcChance + spellbonuses.ProcChance) / 1000.0f;
	
	ProcChance = 0.05f + float(mydex) / 9000.0f; //Base chance, based on dex + static chance to proc
	ProcBonus += (ProcChance * AABonus) / 100; //AA modifier in addition to normal ProcBonus from items & spells, percentage of base chance?
	ProcChance += ProcBonus; //Add the bonuses to the base chance
	mlog(COMBAT__PROCS, "Proc chance %.2f (%.2f from bonuses)", ProcChance, ProcBonus);
	return ProcChance;

So, if we use Jonthan's Mightful Caretaker as our example, the effect_value is 102, which ends up being 1020. In GetProcChances, we start with 0, then the spell value gets divided to 1.02. When we try the proc in Mob::TryWeaponProc (both with & without augs), also in zone/attack.cpp (around line 3674), we generate a random float between 0 & 1. Since 1.02 is always > anything between 0 & 1, we will proc 100% of the time.

I assume this is supposed to be a multiplier (200% = 2x as likely vs base, etc) instead of a direct mod on the proc chance. We should be able to do something like this:

	ProcBonus += float(itembonuses.ProcChance + spellbonuses.ProcChance) / 1000.0f;
	
	ProcChance = 0.05f + float(mydex) / 9000.0f;
	ProcBonus += (ProcChance * AABonus) / 100;
	ProcChance *= ProcBonus; //Multiplier instead of flat bonus
	mlog(COMBAT__PROCS, "Proc chance %.2f (%.2f from bonuses)", ProcChance, ProcBonus);
	return ProcChance;

If someone wants to try this and/or commit to SVN, feel free (I'm having some issues w/ Visual Studio after the change to zone.vcproj).

EDITED By Trevius: Removed stuff related to another thread