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FreeformMathBlock

13.20

Inheritance 1 ancestor · 45 siblings

Class Documentation

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A block that evaluates a text formula and writes the result to Dest. The client parses and evaluates Formula each time the block runs. A formula computes a number, a vector or a bool from literals, script variables and functions.

The result kind decides what the block writes: a bool writes a bool, a number writes a float, and a vector writes a vector3. A formula never produces an int, so a formula that reads only int variables still writes a float.

If the formula cannot be parsed or evaluated, the block reports an invalid expression error and writes nothing. Typical causes are an unknown name, a wrong number of operands or arguments, operand kinds that an operator does not accept, a division by zero, and a negative base for ^.

Properties

Formula

String = ""
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The formula text. Whitespace is ignored.

Values. A formula works with three kinds of value: numbers, 3D vectors and bools.

  • A number literal is written in decimal, and a leading dot is allowed (.25).
  • true and false are bool literals.
  • [x, y, z] is a vector literal.
  • prefix.Name reads a script variable. An int or float variable gives a number, a bool variable gives a bool, and a vector3 variable gives a vector. A variable of another kind, a string for example, cannot be used and makes the formula fail.

The formula language has no comparison operators (<, >, =) and no strings. Comparisons use ComparisonScriptCondition in an IfConditionBlock.

Variables. The prefix selects the script table. The name after the first . is the key in that table. Only these short prefixes are accepted; the full table names are not.

Prefix Table
ptp PassThroughParamsTable
iv InstanceVars
cv CharacterVars
wv WorldVars
sv SpellVars
av AvatarVars
nbv NextBuffVars
nsv NextSpellVars
tt1, tt2, tt3 TempTable1, TempTable2, TempTable3
gsv GameScreenVars

Operators. A higher rank binds tighter. The order is not the order of C or Lua: the logical operators bind tighter than the arithmetic ones, and || binds tighter than &&. For example, a + b && c is a + (b && c), and a || b && c is (a || b) && c. Use parentheses wherever a formula mixes kinds of operator.

Rank Operator Meaning
7 || Logical or. Takes bools or numbers (a number other than 0 is true) and returns a bool.
6 && Logical and, with the same operands as ||.
5 ^ Power, numbers only, right-associative. A negative base is an error.
4 * Multiply: number by number, vector by number, number by vector.
4 / Divide: number by number, vector by number. Division by zero is an error.
4 // Integer divide: both operands are truncated to ints first. A vector divided by a number is divided per component.
4 % Remainder of a float division, numbers only.
3 + - Add and subtract: number with number, vector with vector.
2 - ! (prefix) Negate.

Prefix - and ! are one operator. It negates a number, negates all three components of a vector, and inverts a bool. So !5 is -5, and -true is false.

Functions. A function call is name(argument, ...).

Function Arguments Result
sin, cos, tan number Trigonometric functions.
asin, acos, atan number Inverse functions. The input is clamped to -1..1 and the result is in degrees.
floor, ceil number Rounds down or up.
round number Rounds to the nearest integer, halves away from zero.
abs, log, sqrt, factorial number Absolute value, logarithm, square root, factorial.
min, max two or more numbers The smallest or largest argument.
rand number, number A random integer between the two arguments, both included.
degtorad, radtodeg number Converts degrees to radians, or radians to degrees.
length3d, normalize3d vector Length, or unit vector, in 3D.
length, normalize vector Length, or unit vector, on the ground plane: the Y component is set to 0 first.
dot3d, cross3d, angle3d vector, vector Dot product, cross product, and angle in degrees, in 3D.
dot, cross, angle vector, vector The same on the ground plane, with Y ignored. cross returns a number.
rotate vector, number Rotates the vector around the Y axis.

A function needs exactly the declared kinds of argument, and min and max need at least two.

Example: iv.BaseDamage * (1 + ptp.Bonus) multiplies a variable of the instance table by one plus a parameter.