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Range of illusion dispelling

AlonsoAlonso Member Posts: 806
I'm observing a quite weird behaviour in illusion dispelling spells with SCS. I'm in the graveyard crypts about to enter a room that I know is full of invisible vampires. I cast True Sight from outside that room. True Sight has a very large area of effect, 120 feet, so the whole room is well within its range. Then I send Minsc in, protected by Protection from Undead. As you can see in the picture, True Sight has only revealed one of the vampires. The other vampires remain invisible because they cannot attack Minsc:
d06gd6x79ouh.png

Then I send in Haer' Dalis, who is not protected against the undead. The rest of the vampires attack Haer, becoming visible immediately:
6d246ehkg6yd.png

I have tested this with Oracle and the result is the same. Why are not all the vampires revealed?

I attach a save that you can use to test it yourself.

Comments

  • FlashburnFlashburn Member Posts: 1,847
    True Sight is still affected by line of sight.
    semiticgoddessChroniclergorgonzola
  • semiticgoddesssemiticgoddess Member Posts: 14,903
    I think that's true even if you add the "no LoS" tag to the right spell files, since the range is determined by the repeating spell's projectile ("Instant_Area_Large-Not_Party (BIGNAREA.PRO) - 254") rather than its actual range. You could probably make it affect every non-friendly critter on the map, though, by changing each opcode's target from "Preset Target" to "Everyone except party." In that case, the range would be infinite and map-wide regardless of the spell's range value or projectile.

    Other area-effect spells have the same issue. A Slow spell won't be able to curve around corners; the area of effect expands from its center.
    AlonsoChroniclergorgonzolalolien
  • AlonsoAlonso Member Posts: 806
    edited April 2019
    So I guess this is a bug in the behaviour of all these spells, right?
  • semiticgoddesssemiticgoddess Member Posts: 14,903
    @Alonso: More a fluke of the game engine, really. True Seeing works by repeatedly casting an extra spell every 6 seconds, and that second spell is basically an area-effect, party-friendly spell that removes the effects of illusion spells. The area of effect is granted by an invisible, instantaneous projectile--but, like most projectiles of its type, it doesn't reach around corners.

    It actually makes in-game sense, so I'm not even sure it's contrary to developer intent. True Seeing would let you see through illusions, but it doesn't let you see through walls; that's what Farsight and Clairvoyance do. It makes sense that it wouldn't stretch around corners.

    I mean, in your screenshot, there are 20 feet of solid wall in between the mage and those hidden vampires you want to reveal. True Seeing doesn't let you explore around corners like Farsight or Clairvoyance, nor is there any indication in the spell description that it would do so, so it would be weird if it revealed invisible critters around corners when it couldn't reveal the terrain around corners. The only reason you can see the big table in that screenshot is because Minsc ventured out of the hall.

    The spell is more of a "see through illusions" thing, not a "see through illusions and also walls" thing.
    Grond0ChroniclerAerakarlolien
  • AlonsoAlonso Member Posts: 806
    edited April 2019
    The description says "all hostile illusion/phantasm spells in the area of effect will be dispelled" and "an area roughly 120 feet in radius around the caster will be affected". It says nothing about line of sight or walls affecting the area of effect in any way. Either the description of the spell is wrong or the behaviour is wrong. They cannot be both right at the same time.

    Edit: Typo.
    Post edited by Alonso on
  • ChroniclerChronicler Member Posts: 1,391
    edited April 2019
    No, I'd say it's working as intended.

    Edit: Had this window open for a while and some posts got added before I replied. This looks weird now.
  • semiticgoddesssemiticgoddess Member Posts: 14,903
    Confusion, Ice Storm, Fireball, and Slow are also limited by walls, and none of their spell descriptions mention that, either. That's actually true for every area-effect spell I can think of.
    ChroniclerAlonso
  • ChroniclerChronicler Member Posts: 1,391
    semiticgod wrote: »
    Confusion, Ice Storm, Fireball, and Slow are also limited by walls, and none of their spell descriptions mention that, either. That's actually true for every area-effect spell I can think of.

    In general it seems safe to assume that spells do not pierce walls unless otherwise specified. That'd be a big feature to just not mention. It would let you cast you spell "invisibly" more effectively than many illusion spells. Why cast Shadow Door when you can just cast from behind an actual door?
  • AlonsoAlonso Member Posts: 806
    Actually, there are plenty of spells that go around corners or pierce through walls. This screenshot shows a simple example in which charname casts Web and holds Minsc, who is standing at the other side of a thick wall:
    c6hr8w3ou7x7.png
  • Grond0Grond0 Member Posts: 7,305
    That's a different issue. Spell projectiles only travel in straight lines (in some cases they will move to follow a moving target, which gives the appearance of them travelling in a curved line, though really it's just a continually shifting straight line).

    A spell can either be carried by projectiles directly (like true sight) or originate from the point a projectile reaches (the spell target). In this case you've clearly cast the spell to originate in the corridor where it can spread to Minsc. If you had cast the spell this side of the wall then, even though it would have been close to Minsc, it would not have affected him (as web, like other area effects, can't pass through walls). Similarly, if you tried to cast the spell at Minsc's location directly you would find your character moving into the corridor to do the cast - as the game engine knows the projectile can't go through the wall.
    gorgonzolasemiticgoddess
  • Jaheiras_WitnessJaheiras_Witness Member Posts: 614
    The spell description also does not mention that True Sight is blocked by SI Divination. It does not mention that this spell will not cause neutral characters affected by this spell to become hostile. It does not mention that illusions cast in between the "ticks" of True Sight will persist until the next tick of True Sight. It does not mention that Wild Mages could get a wild surge when casting this spell. It does not mention that True Sight does not enable you to see through floors or ceilings. So if I cast it on the roof of de'Arnise Keep, the yuan-ti mage in the library below does not have its illusions dispelled.

    The spell description does not mention a billion things. That's because it is a summary description that is trying to capture the essence of what the spell does. So I do not understand the mentality of "spell description does not mention = bug". If you can't see through walls, a spell description does not have to state "upon casting this spell you still cannot see through walls" to be accurate.
    gorgonzolaLudwig_IIsemiticgoddessChronicler
  • gorgonzolagorgonzola Member Posts: 3,864
    it has to be told that to dispel an illusion and to have someone that sees it happening are 2 completely different things.
    a blinded mage can use true sight to destroy a pi or reveal an invisible enemy as long as there is no physical obstacle in the line of sight between them and don't see it happening cause he is blind.

    i think that the actual implementation of true sight is good, as it gives more tactical value to the game. i often use it with my thieves or invisible toons to avoid enemy's true sight. scouting (or using metagame knowledge, how Valarien should have known that that particular room is filled with vampires?) and using the terrain features make possible both to use effectively true sight, even if your party should have pulled out something more then "bombing from the fog of war a true sight", and to defend from enemy true sight.
    everything that compel to use the terrain features and good tactics instead of meta knowledge in my book is a very good thing... :)
    Alonso
  • gorgonzolagorgonzola Member Posts: 3,864
    The spell description also does not mention that True Sight is blocked by SI Divination. It does not mention that this spell will not cause neutral characters affected by this spell to become hostile. It does not mention that illusions cast in between the "ticks" of True Sight will persist until the next tick of True Sight. It does not mention that Wild Mages could get a wild surge when casting this spell. It does not mention that True Sight does not enable you to see through floors or ceilings. So if I cast it on the roof of de'Arnise Keep, the yuan-ti mage in the library below does not have its illusions dispelled.
    this is not fair... :D.
    SI protect from every spell of a particular school, and is stated in the spell description, should every other spell have in its description that the right SI makes the spell not effective against the protected character?
    and to have a surge is a chance that a wild mage has casting every spell.
    the roof of the keep and the library are in 2 different areas.
    the only truly missing things are " It does not mention that illusions cast in between the "ticks" of True Sight will persist until the next tick of True Sight"
    and "there must be an unobstructed line of sight between the caster and the illusion".


    Alonso
  • DavidWDavidW Member Posts: 823
    Nothing to do with SCS: as others say, this is vanilla game behavior, and I don’t see any reason to think it’s not intended behavior. Spells, by default, don’t go through walls. (If you want it to go through walls in your local game, just set the ‘goes through walls’ bit in the appropriate .pro file.)
    gorgonzolasemiticgoddess
  • gorgonzolagorgonzola Member Posts: 3,864
    if you have a save game suitable try to have Valarien cast true sight from a position where there is line of sight to the vampires. like from the corridor before the door with the 2 statues, while misc is in the position of the first screenshot. there you have line of sight and all the vampires are inside the aoe range, i am not sure if is possible to include also the only vampire whose invisibility is dispelled in your try without him attacking Valarien, other way your charname can stay a little more right so invisible to that vampire, that also remains invisible, but the others are made visible and minsc can kill them, so you are left with a full party without a single vampire or an other true sight can be used.
    this is an example of what i call to use the terrain features to your advantage.
  • AlonsoAlonso Member Posts: 806
    edited April 2019
    gorgonzola wrote: »
    your party should have pulled out something more then "bombing from the fog of war a true sight", and to defend from enemy true sight.
    everything that compel to use the terrain features and good tactics instead of meta knowledge in my book is a very good thing... :)
    You're such a horrible person, pointing out what a bad player I am :D
    In my defense I will say that, believe it or not, this is effectively my first playthrough (the last time I did a full playthrough was 15 years ago, so I have forgotten almost everything), plus I'm playing SCS in hard difficulty, so my tactical approach is "everything is fair in love and war".

    For the record, the approach I used eventually was to send in summons to bait the vampires into attacking and giving up their invisibility.

    And kudos to @DavidW, as always, for this neat piece of AI (I imagine the AI at play here is SCS rather than vanilla).
    semiticgoddessGrond0gorgonzola
  • AlonsoAlonso Member Posts: 806
    @Grond0: I think what you've said is the same thing I said: Some AoE spells go around corners and some don't. You've just explained it in a more detailed and technical way.

    At any rate, even though I think that now I understand how areas of effect work, I would like to read a complete description, because this is surprisingly complicated. Ideally, a description that somebody new to the game can understand. AFAIK, this has never been explained anywhere.
  • Grond0Grond0 Member Posts: 7,305
    Alonso wrote: »
    @Grond0: I think what you've said is the same thing I said: Some AoE spells go around corners and some don't. You've just explained it in a more detailed and technical way.

    At any rate, even though I think that now I understand how areas of effect work, I would like to read a complete description, because this is surprisingly complicated. Ideally, a description that somebody new to the game can understand. AFAIK, this has never been explained anywhere.

    Unless I've misunderstood your position, we don't agree. In my view there are no AoE spells that go round corners from the point at which the spell emanates. It is of course possible to cast a spell like web from your position so that it triggers at a different location and then affects something around a corner from your location, but that's very different from the argument you seemed to be making about true sight that it should affect things not in a direct line of sight from your character.
    gorgonzola
  • AlonsoAlonso Member Posts: 806
    edited April 2019
    Grond0 wrote: »
    Unless I've misunderstood your position, we don't agree. In my view there are no AoE spells that go round corners from the point at which the spell emanates.
    A remarkable misunderstanding indeed, because I didn't say the opposite. I said that some spells go around corners, meaning they go around corners from the caster to the point where the effects of the spell are happening (as illustrated in the screenshot of the Web spell). Then you went on to confirm what I said and gave some technical details about it.
    Grond0 wrote: »
    the argument you seemed to be making about true sight that it should affect things not in a direct line of sight from your character.
    I didn't make that argument, I didn't say anything about what should or should not happen. I just pointed out that the behaviour of the spell differs from its description, and therefore one of them must be wrong. I didn't say anything about which one is wrong because I don't know. The comments here suggest that the behaviour of the spells is fine, which means that the description is wrong. That makes sense to me, so I guess it must be the right view.
  • FlashburnFlashburn Member Posts: 1,847
    Alonso wrote: »
    Actually, there are plenty of spells that go around corners or pierce through walls. This screenshot shows a simple example in which charname casts Web and holds Minsc, who is standing at the other side of a thick wall:
    c6hr8w3ou7x7.png
    Hmmm. That Web looks like it was cast into the vertical hallway as its center point. Minsc is almost but not quite out of the AoE. If you had cast it into the smaller horizontal hidden door hallway, Minsc would still be a comparable distance into the Web's radius, but would not be affected by it.
    Alonso
  • gorgonzolagorgonzola Member Posts: 3,864
    Alonso wrote: »
    You're such a horrible person, pointing out what a bad player I am :D
    In my defense I will say that, believe it or not, this is effectively my first playthrough (the last time I did a full playthrough was 15 years ago, so I have forgotten almost everything), plus I'm playing SCS in hard difficulty, so my tactical approach is "everything is fair in love and war".
    i am indeed an horrible person >:)
    in my defense i will say that, believe it or not, also i am not the best player around and pointing out in the forums the errors and not completely flawless tactics of the other players is my way to vent my frustration :s about it ;)
    my trusted mouse familiar is the one that fight for me the hardest battles when after many reloads i want to hit the monitor with my war hammer :D

    your tactical approach is sound, considering the situation, the first and most important thing is to beat the game :) , to do it with style B) comes after, when you have figured out the battles.
    and your strategy failed only cause you lacked of a particular knowledge about how the spells aoe work, knowledge that now you have.
    Alonso
  • Grond0Grond0 Member Posts: 7,305
    edited April 2019
    Alonso wrote: »
    Grond0 wrote: »
    Unless I've misunderstood your position, we don't agree. In my view there are no AoE spells that go round corners from the point at which the spell emanates.
    A remarkable misunderstanding indeed, because I didn't say the opposite. I said that some spells go around corners, meaning they go around corners from the caster to the point where the effects of the spell are happening (as illustrated in the screenshot of the Web spell). Then you went on to confirm what I said and gave some technical details about it.

    Really not so remarkable ;). Your original point was about true sight where you clearly suggested that the effect should go through walls. I pointed out that your subsequent reference to web was not an example of a spell going through walls, but a way in which you can cast spells in order to affect those out of sight - that's illustrating tactical use, not a difference in spell behavior or mechanics. If you are now simply saying that you can use some spells to affect people around corners (because you can cast them at range, like fireball) and other spells you can't (because they emanate from the caster, like sunfire) then I agree.
    Grond0 wrote: »
    the argument you seemed to be making about true sight that it should affect things not in a direct line of sight from your character.
    I didn't make that argument, I didn't say anything about what should or should not happen. I just pointed out that the behaviour of the spell differs from its description, and therefore one of them must be wrong. I didn't say anything about which one is wrong because I don't know. The comments here suggest that the behaviour of the spells is fine, which means that the description is wrong. That makes sense to me, so I guess it must be the right view.

    As has been said above it would not be reasonable to say in the summary description for every spell that it doesn't go through walls, so I don't think the specific description is wrong. You could make a case that there should be more description in the manual somewhere about the general behavior of spells (and include there that they don't go through walls), though that sort of level of detail would not typically be found in game manuals.
    gorgonzola
  • gorgonzolagorgonzola Member Posts: 3,864
    Grond0 wrote: »
    You could make a case that there should be more description in the manual somewhere about the general behavior of spells (and include there that they don't go through walls), though that sort of level of detail would not typically be found in game manuals.
    as a player that played bg2 for some time without the manual, a friend gave me his cds but not the manual, then a version with tob and manual, then after some years of playing in complete insulation i had access to the internet and discovered the gaming forums i am maybe entitled on speaking of the level of detail of the manuals, both the old one and the new ee one, and of its usefulness.

    at the beginning, without a previous experience with the pnp game, no internet and no manual i was completely ignoring basic concepts like thac0 or ac. it was clear to me that for some strange reason a lower thac0 and ac was better, but how they work and interact for me was a mistery.
    still after a couple of runs i was able to beat the game quite easily, to use my mages with a certain efficiency, i was even able to kill kangaxx without the green scrolls or the use of si abjuration, as i never discovered haw those tools make the battle trivially easy.
    knowledge 15%
    useful knowledge 15%
    efficiency 40%

    then with the manual, but still not internet what changed? i did read the manual, that had some additional information i could not find in game, and had the descriptions of all the spells, that can be found also in game, but are much more easy to read an learn on a book.

    knowledge 35%
    useful knowledge 18%
    efficiency 41%

    then internet and the forums and you tube (you can find there some rare examples of outstanding play level in a sea of mediocrity)
    knowledge 80%
    useful knowledge 65%
    efficiency 90%

    i am only guessing the percentages, but i hope that what i want to communicate is clear.
    there is very little that i could learn from the manual that i had not discover without it. few runs, starting on easy and finding even the goblins of the starting dungeon hard, then increasing the difficulty up to insane gave me almost the same level of efficiency that i had after reading the manual.
    internet, so the contribution and experience of other players changed everything.

    i agree that a manual does not need a very deep and detailed analysis of the technical aspects of the game.
    but i personally found it almost completely not useful, all appearance, flavor, and 0 substance.
    i learned a lot much on some internet resources like this:
    https://www.sorcerers.net/Games/BG2/SpellsReference/Main.htm
    only few internet pages, but founding and reading them gave me a completely new level of understanding about how the spell system works, while the manual basically gave me no useful information i had not already discovered playing.

    to write on a manual something like:
    "AoE spells: the spell is effective in an area with the radius stated in the spell description, the center point of the aoe is the caster if the spell is on self, like sunfire, or the point where the spell is cast at if is a ranged one, like fireball. a ranged spell can not pass trough walls and closed doors as well as physical obstructions protect the recipient even if he is in the aoe"
    is not complicated, takes only a little space in a manual. written by a native english speaker more skilled then me in this kind of things it probably can be even shorter and easier to understand.

    i agree that is not a good strategy to base our knowledge on the manuals, but i really think that they could add a lot more useful information taking about the same space if their true focus would have been substance and not appearance.
    Grond0Aerakar
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