Chargeable spells.md

Chargeable spells

How do they work? (observation)

Chargeable spells have 4 KEY_INVEST vfx effects defined in VisualFxInst.d file, for example Windfist:

INSTANCE spellFX_Windfist_KEY_INVEST_1 (C_ParticleFXEmitKey) { emCreateFXID = "spellFX_Windfist_INVESTBLAST"; };
INSTANCE spellFX_Windfist_KEY_INVEST_2 (C_ParticleFXEmitKey) { emCreateFXID = "spellFX_Windfist_INVESTBLAST"; };
INSTANCE spellFX_Windfist_KEY_INVEST_3 (C_ParticleFXEmitKey) { emCreateFXID = "spellFX_Windfist_INVESTBLAST"; };
INSTANCE spellFX_Windfist_KEY_INVEST_4 (C_ParticleFXEmitKey) { emCreateFXID = "spellFX_Windfist_INVESTBLAST"; };

By default in G1 spellLevel is set to 0 when player draws spell, VFX that will be played is determined by this spellLevel. spellLevel 0 does not have any VFX effect.

As soon as player starts investing mana spellLevel is increased by SPL_NEXTLEVEL:

func int Spell_Logic_Windfist (var int manaInvested) {
	//Vanilla logic here is messed up, spell is fully charged in 750 ms and is casted in 1000 ms
	//const int SPL_DAMAGE_WINDFIST = 10;
	//const int SPL_SENDCAST_WINDFIST = 3;
	//time_per_mana = 250;
	if (manaInvested == (SPL_SENDCAST_WINDFIST*3)/10) //0.9 rounded to 0	250 ms
	|| (manaInvested == (SPL_SENDCAST_WINDFIST*5)/10) //1.5 rounded to 1	500 ms
	|| (manaInvested == (SPL_SENDCAST_WINDFIST*8)/10) //2.4 rounded to 2	750 ms
	{ return SPL_NEXTLEVEL; };

	if (manaInvested >= SPL_SENDCAST_WINDFIST) {
		return SPL_SENDCAST;
	};

	return SPL_RECEIVEINVEST;
};

In the code above, spellLevel is increaded by mana consumption (3 points of mana!) to level 3. As soon as spell is casted SPL_SENDCAST increases spellLevel by 1 more level to level 4. Fully charged WindFist spell deals 40 points of damage.

Another problem is Spell_ProcessMana_Release that straight up casts spell as soon as player stops with mana investment:

func int Spell_ProcessMana_Release(var int manaInvested) {
	if(Npc_GetActiveSpell(self) == SPL_WINDFIST) {
		return SPL_SENDCAST;
	};

This means player can spam-click spell casting (spell does not consume any mana at all!) and function Spell_Logic_Windfist increases spellLevel to level 1 with 0 invested mana, then Spell_ProcessMana_Release casts spell with SPL_SENDCAST which increases spellLevel to level 2. Spam-clicking therefore does not cost any mana at all and causes 20 points of damage. With rune - this is incredibly exploitable.

Let's fix them: High Level concept description

Spell logic

1. We will not allow player to invest any mana in Spell_Logic_Windfist if he does not have enough mana to invest into a single level. This way player wont loose any mana, and wont be able to exploit casting by spam-clicking.
2. Spell_ProcessMana_Release will consume remaining mana required for next spellLevel. Let's say 1 level requires 10 mana points, player invested 11 mana points and released spell afterwards - we will consume additional 9 points of mana immediately.
3. Spell_Logic_Windfist will always double-check if player has enough mana for investment into next level - if he does not - function will cast spell immediately.

VFX

Our solution will have 4 mana-investing cycles (we have to start from lvl 0, because SPL_SENDCAST always increases spellLevel):

• lvl 0 SPL_SENDCAST increases to lvl 1 dmg 10
• lvl 1 SPL_SENDCAST increases to lvl 2 dmg 20
• lvl 2 SPL_SENDCASTincreases to lvl 3 dmg 30
• lvl 3 SPL_SENDCASTincreases to lvl 4 dmg 40

Level 0 has a disadvantage - there is no vfx effect for mana investing, but we can fix that as well.

After some investigation it seems like in G1 oCSpell.spellLevel is passed to vfx effect oCVisualFX.level and from here after a collision with target oCVisualFX.level defines how much damage is dealt to taget in oSDamageDescriptor.

So here is the idea: as soon as player starts investing mana we will increase oCVisualFX.level by 1 extra level, so if oCSpell.spellLevel is 0, we will set oCVisualFX.level to 1. At the same time we will decrease output of function oCVisualFX::GetLevel.

This way spell requires 4 mana-investing cycles and we will fix all the issues 🔥