Should I Debug AFoW issues...or Switch To UDL Explorer Mode?

Hello!  My group and I are pandemic-come-lately users of Roll20. We tried today for the first time to use Advanced Fog of War so that the players could see the residual map of where they had been. But weirdly only one of the tokens could see the ghost of rooms past. The others couldn't. I'm the GM and even after scrutinizing the token "advanced" settings I couldn't figure out why some could and some couldn't see the areas previously in...but no longer. I was going to post a question asking what might be causing this seemingly inconsistent behavior. But...it appears that UDL has recently progressed enough that maybe I shouldn't bother debugging the old...and just turn on Explorer Mode instead?  So...do you have any idea of why AFoW is working for some but not others. Or...do you recommend I just switch to UDL + Explorer Mode? Many, many thanks, Allen

I would highly recommend sticking with legacy dynamic lighting until it is retired. Users keep encountering bugs that cause vision to not work correctly or reveal hidden portions of the map with UDL. Posting pictures of the page settings as well as the token settings for a token that works and one that does not work go a long way in helping others help you determine the problems in a Dynamic Lighting setup. That being said, my guess is that the working token emits light (whether darkvision or "regular" light) and the others do not. Tokens that do not emit light need to make use of a nominal value (say 60 feet) in the "View Distance" field.

And since you state to be quite new Roll20 users and encountering issues with AFoW, i would suggest to not bother and play with normal FoW and without dynamic lighting until UDL is complete. With normal FoW the GM explicitly reveals area's and those area's stay revealed. It's not as sleek, but you have to offset potential increase of immersiveness to the delay and hassle it causes when players see the full map. I

Thanks, folks! I think you helped me understand better what's going on. But, of course, I'll have to test. I think I expected different app behavior than is actual. Does each token have it's own fog/memory? I thought that since I had "enforce line of sight" turned off...thus allowing all tokens with sight to see wherever there was light, that they would all have the same AFoW revealed squares. (This is sort of the behavior I wanted...one group map traced out by wherever any of the PCs could see... But now I suspect that's not what's happening.) Brian: you mentioned a "view distance" setting. I don't see that. I see a "Reveal Distance" setting. Is that what you mean? If a Dynamic Lighting is on, and a token is located at the very edge of a light emitted by a different token, and the first token has Reveal Distance set to say 40 feet...will that first token now be able to see beyond the light? Or will it simply remove fog in squares beyond the light from that token's AFoW memory...but that token still won't be able to see into those squares until there is some light there? Thanks again! Allen

Allen, I am sorry to say but in my experience over the last 6+ years with roll20 Dynamic Lighting and Advanced Fog of War have never worked together and troubleshooting can't fix it. As Martijn suggested using Dynamic Lighting along with manual reveals with Fog of War is the best solution and the one that I use when I feel the need to hide large areas from my parties. For enclosed areas like dungeons Dynamic Lighting alone is more than enough because the party can not see beyond the range of light anyway. Edit:  When it comes to the Updated Lighting System I would never (have never) used it in a live game as it is still very buggy. I will keep working with it in test games to see how it is improving but until it is a working alternative to the legacy system I will not use it with my games.

Allen C. said: Thanks, folks! I think you helped me understand better what's going on. But, of course, I'll have to test. I think I expected different app behavior than is actual. Does each token have it's own fog/memory? I thought that since I had "enforce line of sight" turned off...thus allowing all tokens with sight to see wherever there was light, that they would all have the same AFoW revealed squares. (This is sort of the behavior I wanted...one group map traced out by wherever any of the PCs could see... But now I suspect that's not what's happening.) Brian: you mentioned a "view distance" setting. I don't see that. I see a "Reveal Distance" setting. Is that what you mean? If a Dynamic Lighting is on, and a token is located at the very edge of a light emitted by a different token, and the first token has Reveal Distance set to say 40 feet...will that first token now be able to see beyond the light? Or will it simply remove fog in squares beyond the light from that token's AFoW memory...but that token still won't be able to see into those squares until there is some light there? Thanks again! Allen Each player  has their own fog of war, and each token they control that has vision can contribute to it. To do what you want, you would need to give control of each PCs character sheet to each player, which is probably not ideal. In general, Enforce Line of Sight should be on. Yes, View Distance was what it was called before they rewrote Dynamic Lighting the previous time. If a token has sight and emits its own light, the radius of that light will clear fog of war. If it does not emit its own light, it will use its Reveal Distance to clear fog of war. If light is on a square, it will be in color and show what is on the token layer. If light does not cover a square and fog of war was cleared for it, only the map layer will be shown in shades of gray.

Hi, Brian, Thank you for your thoughtful reply. The last sentence of your response 3 concerns me. It makes it sound like the player does get information about the map layer in portions of the VTT even if there isn't and has never been light there. But now I think I get your point...for the behavior I want, don't use "Reveal Distance" to clear AFoW squares. Instead only have the "Emits Light" clear squares...but allow every player to control each character sheet that is connected to a token that emits light. I'll experiment this week to see. I'm not sure why you recommend turning on Enforce Line of Sight. I'm trying to create an experience somewhat like we had when we were all playing in person...with the new added "fun" of better accounting for illumination. In the "before times" experience of playing together in person on a battle mat, all the players could see anything that any of the PCs saw. I'm happy to continue that, so that's why I turned off Enforce Line of Sight. Thanks, Allen

Yes, the Reveal Distance was introduced when they rewrote Dynamic Lighting the first time in January 2019 and was fundamentally worse than the View Distance it replaced. In the original version of Dynamic Lighting, View Distance limited how far Dynamic Lighting calculations were made from the token. It was only meant to be used in scenarios that used AFoW without Dynamic Lighting, but this undocumented behavior allowed light sources not controlled by a player to still clear fog of war if they were within that radius from the token. Because Roll20 did not know you could do that, the behavior did not survive the rewrite and  Reveal Distance instead always causes fog of war to clear even if an area was unlit.  Updated Dynamic Lighting will restore this lost functionality with light sources not controlled by a player. The reason I suggested using Enforce Line of Sight was to leverage one of the strengths of the VTT platform which can often be seen as one of the advantages over playing in person. Enforce Line of Sight keeps players from seeing through walls. It allows the kind of slow reveal that we might use in person be removing black pieces of paper that have been cover the map on the tabletop. If all of the players control each other's character sheets, you should still get a shared vision experience where every player sees the same thing, and none of them can see through a wall into the next room. However, it is your game, so go ahead and experiment with the settings to find what works best for you and your players. :)

Fantastic stuff, Brian. If I'm making this change to allow all players to control all PC tokens, I'll experiment to see if I can now return to Enforce Line Of Sight. Thanks.