Stochasm provides some more advanced features for unique art creation, and also scientific use of this app.

Fields

In the Pixels tab, you can specify a field for each pixel type. Fields are used to further adjust the probability that rules are successful when attempted.

For example, consider a reversible flip rule that converts between pixel types A and B, and vice-versa. When the field for both types of pixels is zero (the default), then the rule has the same probability of succeeding in both directions; the success probability for the rule is just set by the parameter you’ve chosen for that rule.

However, you can bias whether a rule will succeed by changing the field for a pixel. It works this way: a rule that transforms pixel type A into type B is more likely to be successful when type B has a high field, and type A has a low (more negative) field. In other words, the rule is more likely to succeed if it is moving “downhill”, from a pixel type with a high field, to a pixel type with a low field.

So, back to the example of the reversible flip rule: if pixel A has a field of 0, and pixel B has a field of 5, then converting pixel type A into type B is less likely to occur than the opposite direction. You can bias the two directions of the move more or less by changing the relative values of the two fields on pixels A and B in the Pixels tab.

To prevent a particular rule from paying attention to fields, check off “Ignore Pixel Fields & Interactions”.

Interactions

Pixel/pixel interaction rules specify whether two types of pixels like to be next to each other on the canvas or not. This influences the success rate of all other rules you have defined that involve these two pixel types. For example, a rule that transforms pixel A into pixel B will be more or less likely to occur depending on the interactions you’ve defined for pixels A and B with their have with their pixels. If turning into type B means that there will be more unhappy contacts with neighbors, then it’s more likely that the pixel will just remain type A when the rule is attempted.

To prevent a particular rule from paying attention to interactions, check off “Ignore Pixel Fields & Interactions”.

Facilitation

The “flip” rules can also have a facilitation condition associated with them. A facilitation condition mandates that the flip rule will only be successful if x or more pixels of a particular type (C) are directly next to the pixel in question on the canvas. The required number x of neighbouring pixels of type C can be between 1 and 8.