(how) Can I do this: zero-based dice pools, pen drawing?

Searching the forums and checking the wiki didn't turn up any applicable info (maybe I used the wrong search terms or something), but I have two questions. Can Roll20 do zero-based dice? Specifically, d10s where the 0 is actually counted as zero instead of 10. As a side effect of this, these dice explode on a roll of 9 instead of 10. I'd like to be able to put in a number of dice (the pool size) and a target number to compare to, and see # of successes (with, of course, the individual die rolls listed). Is that possible? Second, drawing with the mouse is extremely slow and imprecise. Takes hours to get a decent size map in, still looks like junk. Does Roll20 work with pen input? If so, what would be a sufficient system to use? Would I need a Wacom or equivalent, or could I draw with a pen-based tablet like the Tegra / Shield series? Hopefully someone has already done this successfully. If there's existing relevant info I didn't find, I'd be happy to be pointed to it. Thanks :)

I want to say no with the regular dice engine but I think you could do it with the API (mentor level feature) or create a rollable table (that will not dice exploding). If the Wacom or equivalent registers as a mouse then you should be able to use it but functioning like a pen in a photo program, I don't think so. A mod or a dev will have to speak about that. I faintly remember someone talking about using a drawing tablet but never heard anything more about it.

The zero-based dice pool can be done with a d10-1. Though you can't get the explosion on nines I dont think. I could be wrong though. For your map making, you might want to just import maps that you draw on like GIMP or something.

feels stoopid on that first question. I was thinking of something totally else.

You can explode on a specific number by using 1d10!# where # is the number you want to explode on. <a href="https://wiki.roll20.net/Dice_Reference#Exploding_Dice" rel="nofollow">https://wiki.roll20.net/Dice_Reference#Exploding_Dice</a> However, in a system where all dice are counted as 1 less (1 = 0, 10 = 9) then you could just use 1d10!-1.

Hey Gauss! About that way, would the system roll a 10 subtract 1 then roll another d10 and subtract 1 from that? Getting a max of 17 without an additional explosion? 10-1+9-1

Doh, thats what I get for going off of memory. Thanks Jake. Justin , the -1 won't work in combination with exploding. The API (a Mentor level feature) can do it or you could roll /r 1d10-1 and then manually roll again each time you get a 9.

It only subtracts once. However, you can use "!p" instead of just "!" to automatically subtract one from the later rolls, so "1d10!p-1" would give 0-9, with 9's resulting in a 0-9 reroll (and so on as long as you keep rolling 9's). The only thing is that the display would be off (for all 3d dice and for the first die of each roll in the chat log).

Nice find manveti, I often forget about the penetrating.

Regarding the pen drawing - a tablet behaves much the same as any mouse input, so what works with a mouse should work with a tablet - I just wonder if you'd not be better off drawing what you want in GIMP or another image-editing software and importing the map as an image. The only pen-drawing you'd have to do after that might be on the GM layer or, if you have the feature, the dynamic lighting layer. There are even online map-making sites that can create and export a map as an image with textures, walls with shadows, and all that without ever having to use a tablet, which you can then simply import into the tabletop.

Honestly, I'm not so much concerned about having amazing maps, especially to the point of making them in an art program and importing them. I mainly want to be able to draw "on the fly" with decent line/shape quality. This will be more of a sandbox game, so I'd either have to prep very little or way too much. I'll definitely try the penetrating dice roll trick though, thanks for that. Edit: penetrating and exploding don't seem to work together. Is there any good documentation available for the API?