ACE3/addons/advanced_ballistics/functions/fnc_calculateRoughnessLength.sqf
2015-04-07 21:54:29 +02:00

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/*
* Author: Ruthberg
*
* Calculates the terrain roughness length at a given world position
*
* Arguments:
* 0: _this - world position <posASL>
*
* Return Value:
* 0: roughness length <NUMBER>
*
* Public: No
*/
#include "script_component.hpp"
private ["_roughness_lengths", "_windSource", "_nearBuildings", "_isWater"];
// Source: http://es.ucsc.edu/~jnoble/wind/extrap/index.html
_roughness_lengths = [0.0002, 0.0005, 0.0024, 0.03, 0.055, 0.1, 0.2, 0.4, 0.8, 1.6];
_windSource = _this vectorDiff ((vectorNormalized wind) vectorMultiply 25);
_nearBuildings = count (_windSource nearObjects ["Building", 50]);
_isWater = surfaceIsWater _windSource;
if (_nearBuildings == 0 && _isWater) exitWith {
0.0005
};
if (_nearBuildings >= 10) exitWith {
1.6
};
_roughness_lengths select (2 + (_nearBuildings min 6))