Saturday, November 13, 2021

Roll20 is Teaching Me Things About Darkvision

 As I posted earlier, I've been futzing around with Roll20's Dynamic Lighting system.

The goal of this system is to allow you to plop your characters' tokens on a map, and they'll only see on that map what their characters see. As a DM, you might have some monster hiding in the shadows, but if the characters are unable to see it, the players won't.

By default, dynamic lighting assumes there are no light sources on the map. You can alter this in two ways. One is a blanket "daylight mode," in which the whole map is illuminated. The only reason to use this (and not just not use dynamic lighting) is if you want to retain the ability to obscure things. In this case, large objects like buildings can still obscure areas if you paint a sight-obstruction into the map. This could also be used for a well-lit interior dungeon environment. The downside is that the shadows cast by the obstructions are invariably stark black - which can be a bit intense if you're just trying to show that the party can't see behind that big tree.

The other way is by adding light sources via what is essentially a "torch stamp" that they have added. Now, this is something that I've had some issues with when actually using it - I'll put it on the dynamic lighting layer and people won't get any light from it, even though on my GM's screen it shows and even when I "re-enter as player" I still see it. So, either there's bugs to work out or I've missed some element of the UI.

In terms of gameplay, though, one thing that's really interesting about this is how it shows you in real-time the radius of sight for characters with darkvision. Turns out a 60-foot radius is enormous. Then, there's characters like Drow or Deep Gnomes who have 120 feet of darkvision, which is even crazier. A Twilight Cleric, whose darkvision extends 300 feet, basically means practically no map will be large enough to escape their vision (they could see from one side of a 60x60 grid to the other, and Roll20's default map size is 25x25 - less than a quarter the size.)

To be honest, I think that the lighting effect is the coolest with characters who don't have darkvision. I made a map in which there's a lone candle on a desk in an out-of-the-way room. Its 5 feet of bright light and 5 feet of dim light appropriately feel like this minuscule beacon.

I think generally that darkvision is a real time-saver for players and DMs alike. When everyone in the party has darkvision, you don't really need to worry that much about illumination. But as a DM, I do think there are some times when using light can be really exciting. But I do think that sometimes it gets lost a bit when describing things in the "theater of the mind." Generally, humans visualize spaces to make a mental map, and so there's a kind of mental darkvision as you hear a place described, even if you're told you can't see it.

Doing this on a service like Roll20 gives you the visual queue to think about darkness. (It's also fun that individual players only see what their characters do, so if a character with darkvision is warning the character without about the big monster in the shadows, the same asymmetry of information exists for the players.)

I am trying to figure out if Roll20 plays precisely by D&D rules - something a lot of players and DMs forget is that in pitch darkness, a character with darkvision still only sees as if they were in dim light. In practical terms, this only means that they take disadvantage to perception checks (though it should also mean a -5 to passive Perception).

As a DM, you need to also try to separate out what you know versus what your monsters know. For example, my upcoming session of my Ravnica game has the Golgari wing of the Phyrexian conspiracy unleashing a plague of zombies on the surface (honestly, this isn't totally outside of standard Golgari behavior, but I think the version of Ravnica that my campaign takes place in is a somewhat more stable and cooperative one than you might choose to portray). The zombies all have standard 60 foot darkvision, which they'll use to chase down Commoners in order to turn them into Husk Zombies. I might play a little fast and loose with how good the commoners are at evading the zombies. The implication is meant to be that this is happening across the 10th District, so the commoners won't necessarily know to run off the map. I'm leaving it up to the players to figure out how to corral the commoners to keep them safe (or if they think scattering them would be wiser). But I'm considering giving the monster tokens their own visual ranges to make sure that they can sense the living mortals they're trying to convert.

I think ever since I took a class my freshman or sophomore year of high school called "Back Stage Magic," which was about the tech side of theater (I still wound up doing more acting and some writing/directing, but the tech stuff was also something I found cool) I've really enjoyed seeing what one can do with lighting to change the feel of an environment. If you've ever been on a Disney ride when it breaks down and they turn the "house lights" on, it's shocking how immersion-breaking the effect can be. But that just goes to show you how effective the lighting design was to begin with.

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