Missileguidance - Use checkVisibility to test LOS for missile seekers

[BaerMitUmlaut]

When merged this pull request will:

• Make missiles using optical guidance (for example the Javelin) now lose lock once the target gets behind smoke

0.001 as a visibility limit seemed reasonable with my testing with a smoke grenade, I'd rather go higher (missiles would then easier lose lock) than lower. If a tank pops a smoke wall, it should be well within that limit anyways.

Not tested with actually firing a missile yet, since the tank would have to pop smoke at just the right time and also be moving, because the missile will still fly straight if it loses lock.

Closes #7012, also ref. #6744 which still needs additonal code when actually locking on to fix completely.

[Drofseh]

Most thermal sensors see through smoke, unless that smoke is specifically designed to be opaque to thermal EM.

[severgun]

unless that smoke is specifically designed to be opaque to thermal EM.

And all of vehicle smokes are such kind of. Isn't it?

[Drofseh]

Only the more modern ones, since around the mid-80's.

[BaerMitUmlaut]

In Arma all smoke is thermally opaque afaik. I don't know any optically guided fire and forget ATGMs that were developed before the 80s either.

[Drofseh]

Right, but you could be firing a modern weapon at an older tank.
Say a Javelin at a T-55.

[jonpas]

Could add a config entry to at least give the option to change it per tank/missile.

[TheCandianVendingMachine]

I don't think that's feasible. Some missiles don't lock on to targets but would still be affected by thermal smoke

[BaerMitUmlaut]

@jonpas no, you couldn't. How would you know that the smoke that's blocking LOS was caused by that vehicle?

Again, since all smoke is thermally opaque in Arma and you'd have the same problem in vanilla, I'd rather go for this option. The T-55 might have been equipped with newer smoke ammo after all.

[jonpas]

Yes, I tend to agree. This is the best we can do at the moment.

[PabstMirror]

We could check normal lis and checkVisibility, if checkVis is blocked then check for presence of vehicle based smoke (SmokeShellVehicle)

I guess to be perfect you would have to check for smoke at multiple points on a line from missile to target, but missile should be up high and I think just checking at target is fine.

Vanilla/CUP/RHS both seem to be using SmokeLauncherMag, which is a scripted ammo that launches SmokeShellVehicle

params ["_seeker", "_target"];

if (!((lineIntersectsSurfaces [getPosASL _seeker, aimPos _target, _seeker, _target]) isEqualTo [])) exitWith { false };

private _visibility = [_seeker, "VIEW", _target] checkVisibility [getPosASL _seeker, aimPos _target];
if (_visibility > 0.001) exitWith { true };

// Check if visibility is blocked due to vehicle based smoke launcher
// Note: bis_fnc_effectfiredsmokelauncher spawns SmokeShellVehicle, but particle effects are scripted?
private _shells = _target nearObjects ["SmokeShellVehicle", 30];
_shells isEqualTo [] // return

edit: we should also ace_cough when players walk through vehicle smoke 😉

[BaerMitUmlaut]

lis is not necessary, checkVisibility takes care of that and will do multiple ray casts.
What if visibility is low because a bush, but there is no vehicle smoke involved? This would also require special magazines for non-thermal blocking smoke. Really not a fan of making this more complex than necessary.

[Gwynblade]

Speaking of thermally opaque smoke, is it possible to make the smoke not be thermally opaque?
Having a variant of smoke grenades that don't block thermals would add an interesting gameplay mechanic (for infantry smokes I mean).

I wanted to post this in feature requests ages ago, but figured something like this is probably not possible.