40 lines
1.2 KiB
C++
40 lines
1.2 KiB
C++
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// Copyright (C) 2005 Splash Damage Ltd.
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//
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#include "../precompiled.h"
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#pragma hdrstop
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idRandom idRandom::staticRandom;
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idVec3 idRandom::RandomVectorInCone( float halfOpeningAngle ) {
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// This should give uniform distribution: http://www.flipcode.org/cgi-bin/fcmsg.cgi?thread_show=7028
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// Random height between cos(hO), 1
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float c = idMath::Cos( DEG2RAD( halfOpeningAngle ) );
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float z = c + ( 1.0f - c ) * RandomFloat();
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// Random between 0, 2 PI
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float a = RandomFloat() * ( 2.0f * idMath::PI );
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// Make sure vector is normalized & apply azimuth
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float r = idMath::Sqrt( 1.0f - z*z );
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float sin, cos; idMath::SinCos( a, sin, cos );
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return idVec3( r * cos, r * sin, z );
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}
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idVec3 idRandom::RandomVectorInCone( idVec3 dir, float halfOpeningAngle ) {
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// Random height between cos(hO), 1
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float c = idMath::Cos( DEG2RAD( halfOpeningAngle ) );
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float x = c + ( 1.0f - c ) * RandomFloat();
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// Random between 0, 2 PI
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float a = RandomFloat() * ( 2.0f * idMath::PI );
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// Make sure vector is normalized & apply azimuth
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float r = idMath::Sqrt( 1.0f - x*x );
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float sin, cos; idMath::SinCos( a, sin, cos );
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idVec3 result( x, r * cos, r * sin );
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return result * dir.ToMat3();
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}
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