Unity Plugin (UP) & API
Node Modifiers connect two Nodes.
They enable changes in the state of one Node (its origin) to modify the number of Resources in another Node (the target Node), according to the Node Modifier’s Formula (M).
When the origin Node changes, it influences the target Node in the next time step. More than one origin Node can modify a target Node. The formula for this is nearly identical to the formula used for Formula Modifiers:
Nt + 1 = Nt + ∑ ( M × S )
Take this example from Settlers of Catan.
! Click on the double-edge Sources (Settlement & City).
Players gain 1 Victory Point for each settlement and 2 Victory Points for each city. The number of settlements is one Origin Node, the number of cities is a second Origin Node, and both modify the Target Node, which is the player’s total number of victory points.
Node Modifiers can have Formulas that are fractions, for example, +1/3 or -2/4.
In this case, the number of Resources of a target Node is modified by the value indicated by the fraction’s numerator every time there is a change to the number of Resources on the origin divided by the fraction’s denominator and rounded down.
This way, when the number of Resources on an origin Node changes from 7 to 8, the number of Resources on the target is lowered by 2 if the modifier is -2/4, but if the modifier is +1/3, the number of Resources on the target node does not change.
See the example diagram below.
For a more in-depth explanation of how Formulas work, read
If at the start of a Play the Origin Node already has an input to transmit to its Target, then this change takes effect at the beginning of the 1st Step of the execution. After this, the Node will only affect its Target if its state changes. See the example below.
Think of it in terms of programming, as initializing a variable.