76 lines
2.1 KiB
C++
76 lines
2.1 KiB
C++
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//========= Copyright <20> Valve Corporation, All rights reserved. ============//
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#include "sphere.h"
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//#include "body.h"
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//#include "gjk.h"
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//#include "toi.h"
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//--------------------------------------------------------------------------------------------------
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// Local utilities
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//--------------------------------------------------------------------------------------------------
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static void CastStationaryHit( CShapeCastResult& out, float c, const Vector &p, const Vector &m, float mm )
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{
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// return a sphere hit for zero-length ray at point p, with
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// m = p - m_vCenter
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// mm = DotProduct( m, m )
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// c = mm - Sqr( m_flRadius )
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if( c <= 0 )
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{
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out.m_flHitTime = 0;
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out.m_vHitPoint = p;
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if( mm > FLT_EPSILON )
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{
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out.m_vHitNormal = m / sqrtf( mm );
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}
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else
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{
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out.m_vHitNormal = Vector( 0,0,1 );
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}
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}
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else
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{
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// we didn't hit - we're outside and we don't move
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out.m_flHitTime = FLT_MAX;
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}
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}
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//--------------------------------------------------------------------------------------------------
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void CastSphereRay( CShapeCastResult& out, const Vector &m, const Vector& p, const Vector& d, float flRadius )
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{
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float a = DotProduct( d, d ), mm = DotProduct( m, m ), c = mm - Sqr( flRadius );
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if( a < FLT_EPSILON * FLT_EPSILON )
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{
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// we barely move; just detect if we're in the sphere or not
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CastStationaryHit( out, c, p, m, mm );
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return;
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}
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float b = DotProduct( m, d ); // solve: at^2+2bt+c=0; t = (-b<>sqrt(b^2-ac))/a = -b/a <20> sqrt((b/a)^2-c/a))
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float D = Sqr( b ) - a * c;
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if( D < 0 )
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{
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// no intersection at all
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out.m_flHitTime = FLT_MAX;
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return;
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}
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float sqrtD = sqrtf( D );
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float t = ( -b - sqrtD ) / a;
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if( t < 0 )
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{
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// this was the first hit in the past - determine if we're still inside the sphere at time t=0
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// we could do that by checking if float t1 = ( b + sqrtD ) / a; is > 0 or not, but it's easier to:
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// we barely move; just detect if we're in the sphere or not
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CastStationaryHit( out, c, p, m, mm );
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}
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else
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{
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out.m_flHitTime = t;
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Vector dt = d * t;
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out.m_vHitPoint = p + dt;
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out.m_vHitNormal = ( m + dt ) / flRadius; // Should I normalize this here or is this sufficient precision?
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}
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}
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