Expression Bool

Overview

Produces one true / false value from a short expression. Instead of arranging compare and logical-operation nodes, write a compound condition in one expression, such as flag || x > 0.5. Send the result to a switch or gate condition.

Usage tips

• Keep a simple comparison that needs only one compare as a node. Once two or more conditions interact, consolidating them here makes the graph easier to read.
• Because time / frame are available, one expression can describe temporal conditions such as "true only on certain frames" (for example, frame % 4 == 0).
• This also works as a test bench for a list_filter predicate because it uses the same expression syntax.

Related nodes

• compare / value_match — use nodes for simple decisions
• switch / gate — destinations for the Bool value
• expression_float / expression_vec2 — other types using the same expression engine
• list_filter — list-based conditional expressions

Read this first

• The x, y, vec, and flag names here are separate from variables created in the Variables panel.
• They are the input pin names of the Expression node itself.
• You can also enter x, y, vec_x, vec_y, and flag directly in the Inspector.
• To use a variable from the Variables panel, retrieve it with Variable Ref or a similar node and connect it to the relevant input pin.
• When a value is connected to an input pin, the input-pin value takes precedence over the Inspector value.
• Unconnected inputs use the following values:
  • x, y = 0
  • vec = [vec_x, vec_y]
  • flag = false

Available features

• Variables: x, y, vec, vx, vy, flag, time, frame, total_frames
• Operators: + - * / %, == != < <= > >=, && || !
• Functions: min, max, clamp, abs, floor, ceil, round, sign, sin, cos, tan, sqrt, pow, lerp, vec2, x, y, length, if

Common expressions

• x < 0.5
• flag || x > 0.5
• length(vec) >= 4

Concrete examples

Example 1: Threshold test

• Set x to 0.25
• expression = x < 0.5

value = true

Example 2: Compound condition

• Set flag to false
• Set x to 0.8
• expression = flag || x > 0.5

value = true

When to use it

• When you want to produce a Bool for a Switch or filter condition with only a lightweight expression
• When you want to test a List Filter predicate on its own first

Notes

• && / || skip the right side once the result is known. if(condition, A, B) evaluates only the selected branch, so an error in the unselected branch does not affect the result.
• Numeric rules match the Math nodes: reversed clamp bounds are swapped, sign(0) = 0, and % is a non-negative Euclidean remainder. Division or modulo by zero and sqrt of a negative value produce an error.
• Values other than Bool can be evaluated, but the final result is converted to true / false.
• This is not intended for writing complex state machines.
• While you type an expression, the incomplete intermediate text is evaluated immediately, so an error may appear temporarily.