Simple Expression

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Simple expressions are not as flexible as normal scripts, but they are compiled for a very efficient execution.

Available Operators

randomGen a random value from 0 to a (randomGen 5)
randomGen expr random value from 0 to expression value (randomGen daylight)
a factor [x,y] factor is the same as interpolate only output range is fixed and capped to 0...1 (or 1...0 if input range is reversed)


a<=x: 0
a>=y: 1
x<=a<=y: ratio between x and y

Note: works fine even for x>y (calculated as 1-a factor [y,x])

a interpolate [xFrom,xTo,resFrom,resTo] Introduced in ArmA 2 1.05. interpolate result based on input value.

Equivalent to x factor [xFrom,xTo] * (resTo-resFrom) + resFrom

a min b see min
a max b see max
a - b see a-b
a + b see a+b
a * b see a*b
a / b see a/b (for A3, not sure if others)
abs a see abs (introduced in Arma 3 patch 1.68)
x envelope [a,b,c,d] trapezoid envelope with output <0;1> (substitution for "(v factor(a,b))*(v factor(d,c))" (Since Arma 3 1.67)

envelope graph

Description: a,b can be any simple expression. x,y can be a constant expression only (i.e. expression with a type Number).

Since Arma 3 1.67 the following operators are also available (v ... controller value):

  • abs(v) - absolute value
  • sqr(v) - square value
  • sqrt(v) - square root value
  • pow(v, a) - power

SQF Equivalent of factor

SQF_fnc_factor = 
{
	private _fnc_interpolateCommon = 
	{
		params ["_c", "_cMin", "_cMax", "_vMin", "_vMax"];
		
		if (_c < _cMin) exitWith { _vMin };
		if (_c > _cMax) exitWith { _vMax };
	
		(_c - _cMin) * (1 / (_cMax - _cMin)) * (_vMax - _vMin) + _vMin
	};
	
	params ["_c", "_cMin", "_cMax"];
	
	if (_cMin < _cMax) then
	{
		[_c, _cMin, _cMax, 0, 1] call _fnc_interpolateCommon
	}
	else
	{
		[_c, _cMax, _cMin, 1, 0] call _fnc_interpolateCommon
	};
};

Example: [0.2, 0.1, 0.7] call SQF_fnc_factor; // 0.166667

SQF Equivalent of interpolate

SQF_fnc_interpolate = 
{
	private _fnc_interpolateCommon = 
	{
		params ["_c", "_cMin", "_cMax", "_vMin", "_vMax"];
		
		if (_c < _cMin) exitWith { _vMin };
		if (_c > _cMax) exitWith { _vMax };
	
		(_c - _cMin) * (1 / (_cMax - _cMin)) * (_vMax - _vMin) + _vMin
	};
	
	params ["_c", "_cMin", "_cMax", "_vMin", "_vMax"];
	
	if (_cMin < _cMax) then
	{
		[_c, _cMin, _cMax, _vMin, _vMax] call _fnc_interpolateCommon
	}
	else
	{
		[_c, _cMax, _cMin, _vMax, _vMin] call _fnc_interpolateCommon
	};
};

Example: [0.2, 0.1, 0.7, 0, 100] call SQF_fnc_interpolate; // 16.6667

SQF Equivalent of envelope

SQF_fnc_envelope = 
{
	private _fnc_interpolateCommon = 
	{
		params ["_c", "_cMin", "_cMax", "_vMin", "_vMax"];
		
		if (_c < _cMin) exitWith { _vMin };
		if (_c > _cMax) exitWith { _vMax };
	
		(_c - _cMin) * (1 / (_cMax - _cMin)) * (_vMax - _vMin) + _vMin
	};
	
	params ["_x", "_a", "_b", "_c", "_d"];

	private _ret = 0;
	
	if (_x > _a && _x < _d) then
	{
		private _v = [_x, _a, _b, 0, 1] call _fnc_interpolateCommon;
		
		if (_v > 0) then { _ret = _v * ([_x, _c, _d, 1, 0] call _fnc_interpolateCommon) };
	};
	
	_ret
};

Example: [0.5, 0.1, 0.3, 0.7, 0.9] call SQF_fnc_envelope; // 1

Simple Expressions - How do they work?

The following is an example taken from the Eden Editor: Entity Context Menu.

Example: conditionShow = "hoverObjectCanFly * (1 - hoverObjectFlying)"; Entry will only show if the object you are hovering over can fly and the object isn't flying.

Let's take a closer look at the example.

hoverObjectCanFly and hoverObjectFlying are two boolean values, which can either be true (0) or false (1).

If hoverObjectCanFly is true (1) and hoverObjectFlying is false (0) the resulting equation looks like this: 1 * (1-0) = x 1 * 1 = x x = 1 The result will be true (1), therefore the entry will be shown.