54 lines
1.6 KiB
C++
54 lines
1.6 KiB
C++
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/* ========================================================================
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(C) Copyright 2023 by Molly Rocket, Inc., All Rights Reserved.
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Please see https://computerenhance.com for more information
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======================================================================== */
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/* ========================================================================
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LISTING 65
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======================================================================== */
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static f64 Square(f64 A)
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{
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f64 Result = (A*A);
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return Result;
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}
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static f64 RadiansFromDegrees(f64 Degrees)
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{
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f64 Result = 0.01745329251994329577 * Degrees;
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return Result;
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}
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// NOTE(casey): EarthRadius is generally expected to be 6372.8
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static f64 ReferenceHaversine(f64 X0, f64 Y0, f64 X1, f64 Y1, f64 EarthRadius)
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{
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/* NOTE(casey): This is not meant to be a "good" way to calculate the Haversine distance.
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Instead, it attempts to follow, as closely as possible, the formula used in the real-world
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question on which these homework exercises are loosely based.
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*/
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f64 lat1 = Y0;
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f64 lat2 = Y1;
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f64 lon1 = X0;
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f64 lon2 = X1;
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f64 dLat = RadiansFromDegrees(lat2 - lat1);
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f64 dLon = RadiansFromDegrees(lon2 - lon1);
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lat1 = RadiansFromDegrees(lat1);
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lat2 = RadiansFromDegrees(lat2);
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f64 a = Square(sin(dLat/2.0)) + cos(lat1)*cos(lat2)*Square(sin(dLon/2));
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f64 c = 2.0*asin(sqrt(a));
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f64 Result = EarthRadius * c;
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return Result;
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}
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