Dice roller

Contribution by Griatch, 2012, 2023

A dice roller for any number and side of dice. Adds in-game dice rolling (like roll 2d10 + 1) as well as conditionals (roll under/over/equal to a target) and functions for rolling dice in code. Command also supports hidden or secret rolls for use by a human game master.

Installation:

Add the CmdDice command from this module to your character’s cmdset (and then restart the server):

# in mygame/commands/default_cmdsets.py

# ...
from evennia.contrib.rpg import dice  <---

class CharacterCmdSet(default_cmds.CharacterCmdSet):
    # ...
    def at_cmdset_creation(self):
        # ...
        self.add(dice.CmdDice())  # <---

Usage:

> roll 1d100 + 2
> roll 1d20
> roll 1d20 - 4

The result of the roll will be echoed to the room.

One can also specify a standard Python operator in order to specify eventual target numbers and get results in a fair and guaranteed unbiased way. For example:

> roll 2d6 + 2 < 8

Rolling this will inform all parties if roll was indeed below 8 or not.

> roll/hidden 1d100

Informs the room that the roll is being made without telling what the result was.

> roll/secret 1d20

This a hidden roll that does not inform the room it happened.

Rolling dice from code

You can specify the first argument as a string on standard RPG d-syntax (NdM, where N is the number of dice to roll, and M is the number sides per dice):

from evennia.contrib.rpg.dice import roll

roll("3d10 + 2")

You can also give a conditional (you’ll then get a True/False back):

roll("2d6 - 1 >= 10")

If you specify the first argument as an integer, it’s interpret as the number of dice to roll and you can then build the roll more explicitly. This can be useful if you are using the roller together with some other system and want to construct the roll from components.

roll(dice, dicetype=6, modifier=None, conditional=None, return_tuple=False,
      max_dicenum=10, max_dicetype=1000)

Here’s how to roll 3d10 + 2 with explicit syntax:

roll(3, 10, modifier=("+", 2))

Here’s how to roll 2d6 - 1 >= 10 (you’ll get back True/False back):

roll(2, 6, modifier=("-", 1), conditional=(">=", 10))

Dice pools and other variations

You can only roll one set of dice at a time. If your RPG requires you to roll multiple sets of dice and combine them in more advanced ways, you can do so with multiple roll() calls. Depending on what you need, you may just want to express this as helper functions specific for your game.

Here’s how to roll a D&D advantage roll (roll d20 twice, pick highest):

    from evennia.contrib.rpg.dice import roll

    def roll_d20_with_advantage():
        """Get biggest result of two d20 rolls"""
        return max(roll("d20"), roll("d20"))

Here’s an example of a Free-League style dice pool, where you roll a pile of d6 and want to know how many 1s and sixes you get:

from evennia.contrib.rpg.dice import roll

def roll_dice_pool(poolsize):
    """Return (number_of_ones, number_of_sixes)"""
    results = [roll("1d6") for _ in range(poolsize)]
    return results.count(1), results.count(6)

Get all roll details

If you need the individual rolls (e.g. for a dice pool), set the return_tuple kwarg:

roll("3d10 > 10", return_tuple=True)
(13, True, 3, (3, 4, 6))  # (result, outcome, diff, rolls)

The return is a tuple (result, outcome, diff, rolls), where result is the result of the roll, outcome is True/False if a conditional was given (None otherwise), diff is the absolute difference between the conditional and the result (None otherwise) and rolls is a tuple containing the individual roll results.

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