ACE3/addons/weather/functions/fnc_calculateRoughnessLength.sqf
2022-02-17 11:24:28 -06:00

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#include "script_component.hpp"
/*
* Author: Ruthberg
* Calculates the terrain roughness length at a given world position
*
* Arguments:
* world position <posASL>
*
* Return Value:
* roughness length <NUMBER>
*
* Example:
* (getPosASL player) call ace_weather_fnc_calculateRoughnessLength
*
* Public: No
*/
// Source: http://es.ucsc.edu/~jnoble/wind/extrap/index.html
#define ROUGHNESS_LENGTHS [0.0002, 0.0005, 0.0024, 0.03, 0.055, 0.1, 0.2, 0.4, 0.8, 1.6]
private _windSource = _this vectorDiff ((vectorNormalized wind) vectorMultiply 25);
private _nearBuildingCount = {
// Filter lights - fixes high roughness on airports (#6602)
str _x find "light" == -1
} count (ASLToAGL _windSource nearObjects ["Building", 50]);
private _isWater = surfaceIsWater _windSource;
if (_nearBuildingCount == 0 && _isWater) exitWith {
0.0005
};
if (_nearBuildingCount >= 10) exitWith {
1.6
};
ROUGHNESS_LENGTHS select (2 + (_nearBuildingCount min 6))