Implement rotation and free shooting about gothicfreeaim

[szapp]

Fix #10 implement free shooting

[szapp]

Constrain this issue to rotation and free shooting.

[szapp]

Free rotation is implemented.

Separately for runes and scrolls, oCMag_Book::Spell_Cast calls oCSpell::Setup. This function performs a check on oCSpell.targetCollectAlgo and then presumably (?) calls oCVisualFX::Init (0x491F20). This, in turn, sets up the trajectory of the spell fx according to the passed target vob.

Finding out where best to manipulate this target vob is the next step.

[szapp]

The address to inject the aim vob at should be in this engine function.

0x4861D0          int __thiscall oCSpell::IsValidTarget(zCVob*)

In that function, the target vob is validated. This entails checking if its type matches oCSpell.targetCollectType and if it is in line of sight.
An appropriate address to hook within this function is after both checks are performed to overwrite the return value as well as the vob itself (to the aim vob). This will set the aim vob as focus vob for the spell and have it always valid, even when out of line of sight.

Allow free aiming only for spells whose property targetCollectAlgo is one of the following.

• TARGET_COLLECT_NONE
• TARGET_COLLECT_FOCUS_FALLBACK_NONE

[szapp]

Pick up the work on free aim for spells.

[szapp]

Update issue details to generalize to free aim for spells.

[szapp]

At the moment, work is focused on finalizing and stabilizing free aiming. After it has been solved for ranged combat (bow and crossbow), the work on blink and spells in general will be picked up again.

[szapp]

It might even be a nice idea to create a distributor like Spell_ProcessMana. Spell_ProcessMana calls the respective Spell_Logic_* function of each spell. The function to hook oCSpell::Setup could be just like that calling each (the spells that are actually entered there) spell's Spell_Invest_* function. This would offer additional control over spells with this general structure:

instance  Spell_Name () // Settings
func  int Spell_Logic_Name(var int manaInvested) // Previous invest loop (as before: trigger FX-levels and timed events)
func void Spell_Invest_Name() // NEW (for frame-based operations like aiming; only necessary for certain invest spells of course)
func void Spell_Cast_Name(var int spellLevel) // Cast function (as before: decrease mana, cast the spell if it is not an invest spell)

Analogous to Spell_ProcessMana:

const int oCSpell__Setup = 4737328; //0x484930
HookEngineF(oCSpell__Setup, 7, Spell_ProcessInvest);

func void Spell_ProcessInvest(/* Is it possible to ask for arguments here? */) {
    // Get self and other (or item)
    self = _@(MEM_ReadInt(ESP+4)); // Self is a global instance (Classes.d) and will stay set in the functions below
    var int targetPtr; targetPtr = MEM_ReadInt(ESP+8);
    if (Hlp_Is_oCNpc(targetPtr)) { other = _@(targetPtr); } // Other is a global instance (Classes.d) and will stay set in the functions below
    else if (Hlp_Is_oCItem(targetPtr)) { item = _@(targetPtr); }; // Item is a global instance (Classes.d) and will stay set in the functions below

    // From here on it's the usual (like in Spell_ProcessMana and Spell_ProcessManaRelease)
    var int activeSpell; activeSpell = Npc_GetActiveSpell(self); // Could also be retrieved with ESP+12 but this looks more familiar

    // ...
    if (activeSpell == SPL_Blink) { Spell_Invest_Blink(); return; };
    // ...

    // Spells that don't need to hook the function should just not be listed here. Same as in Spell_ProcessManaRelease.
};

func void Spell_Invest_Blink() {
    if (!Npc_IsPlayer(self)) { return; }; // Only player is allowed to use this spell anyway
    // ...
    var int ptr; ptr = ESP+8; // Not sure about the offset here
    MEM_WriteInt(ptr, vobPtr); // The variable vobPtr points to the aim vob
};

[szapp]

If this works, it is probably not even necessary to create the aim vob as oCItem.

[szapp]

One likely solution might be to change the hook. Hook this function instead (or additionally) to unconditionally change the target vob:

const int oCSpell__Setup = 4737328; //0x484930
HookEngineF(oCSpell__Setup, 7, Spell_Invest_Blink);

func void Spell_Invest_Blink() {
    // ...
    var int ptr; ptr = ESP+8; // Not sure about the offset here
    MEM_WriteInt(ptr, vobPtr); // The variable vobPtr points to the aim vob
};