Vision along a diagonal always has Euclidian range even if page measurement is sent to D&D 5e/4e

I was DM'ing a session Saturday and there was confusion about a ranged attack coming at a PC along a diagonal.  The PC couldn't see the enemy because it was out of their 60 foot darkvision range.  When I measured with the ruler, the enemy was 55 feet away along a diagonal, but the PC's vision only extended about 45 feet away on the diagonal, though it is 60 feet on the horizontal/vertical.  The page measurement style was set to D&D 5e/4e, but the darkvision was Euclidian and appeared round rather than square.  This means enemies that are within 60 feet spell/attack range on a diagonal are not visible to the player, even though they should see them according to the 5e measurement rules.  I would think if the page measurement is set to D&D 5e/4e, the darkvision should match that measurement style and appear square, not circular.  This happened under both LDL and UDL.  This seems like a bug, but maybe I'm missing something? Reproduce by: set page measurement style to D&D 5e/4e.  Create a token with 60 feet of darkvision, and measure their visual range along a diagonal and see that it is 45 feet and not 60 feet.

Yes, with the 5e/4e measurement rules, darkvision would become a square around the character that is 125 ft x 125 ft (60 ft either side of the token). I don't think that roll20 has ever done sight on anything other than a circular radius.

5e doesn't even obey this rule themselves. If you look at all of their template examples, a 40' radius fireball is a circular area. In my own game I use Euclidean for Auras and AOEs, but 4e/5e for ranges and movement. I treat vision like an aura/AOE for this purpose. It's an odd hybrid, but at least its consistent and works well with the tool set.

This is a valid point, but I guess there's a design decision in there - having everything on the canvas as a square would look a little funny (well... except squares, which would look even funnier). I'm assuming the non-Euclidean diagonals were an attempt to streamline the game for tabletop so you don't need to measure movement on a battlemap. Since Roll20 has a built in ruler, you could just switch to Euclidean in the page settings. It's not a bad option - you can use right mouse button to set waypoints while you drag the ruler around, then use X to bring up the last path you drew. That would make it pretty easy to plan a movement without too much effort, and all the circular templates & vision ranges would actually make sense. I would be keen to see a square lighting system as an option, but knowing very little about how a lighting system is built I have no idea how much work this would be (presumably too much to be worth the effort, unlike auras).

Thanks for the replies everyone and for the suggestion Oosh!  While it seems counter-intuitive to switch the measurement from D&D 5e/4e to Euclidean when playing D&D 5e, it does solve the inconsistencies with vision distance, AOE, movement distance, etc.  I think we'll give it a go this weekend!

Even when we still played in person, we were gridless in encounters and would use small measuring sticks for distance (or just eyeball it). All my games and marketplace products use Euclidian measurement because it works really well with more natural movement in Roll20. It is generally faster to move and measure as Oosh suggests (pressing the "Q" key also sets waypoints) than to count squares, and every gets to see what someone is doing. Give it a try. There is a non-zero chance you will like it! ;)

Remul said: Thanks for the replies everyone and for the suggestion Oosh!  While it seems counter-intuitive to switch the measurement from D&D 5e/4e to Euclidean when playing D&D 5e, it does solve the inconsistencies with vision distance, AOE, movement distance, etc.  I think we'll give it a go this weekend! For 5E, you can use the Pathfinder/3E version of distance - the first diagonal costs 5ft, the second diagonal costs 10 ft.  It isn't true euclidian, but it is closer than 5E standard rules - and a VTT can do the calculation automatically and quickly for you (the Q key to show your path while moving a token displays the distance you've moved so far - Q to add a waypoint mid-move helps go round corners too).