153 lines
3.5 KiB
C++
153 lines
3.5 KiB
C++
//========= Copyright Valve Corporation, All rights reserved. ============//
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//
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// Purpose:
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//
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// $NoKeywords: $
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//
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//=============================================================================//
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#include "rope_physics.h"
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#include "tier0/dbg.h"
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// memdbgon must be the last include file in a .cpp file!!!
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#include "tier0/memdbgon.h"
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CBaseRopePhysics::CBaseRopePhysics( CSimplePhysics::CNode *pNodes, int nNodes, CRopeSpring *pSprings, float *flSpringDistsSqr )
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{
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m_pNodes = pNodes;
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m_pSprings = pSprings;
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m_flNodeSpringDistsSqr = flSpringDistsSqr;
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m_flSpringDist = m_flSpringDistSqr = 1;
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Restart();
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// Initialize the nodes.
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for ( int i=0; i < nNodes; i++ )
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{
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pNodes[i].m_vPos.Init();
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pNodes[i].m_vPrevPos.Init();
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pNodes[i].m_vPredicted.Init();
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}
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SetNumNodes( nNodes );
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m_pDelegate = NULL;
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}
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void CBaseRopePhysics::SetNumNodes( int nNodes )
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{
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m_nNodes = nNodes;
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// Setup the springs.
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for( int i=0; i < NumSprings(); i++ )
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{
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m_pSprings[i].m_pNode1 = &m_pNodes[i].m_vPos;
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m_pSprings[i].m_pNode2 = &m_pNodes[i+1].m_vPos;
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Assert( m_pSprings[i].m_pNode1->IsValid() );
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Assert( m_pSprings[i].m_pNode2->IsValid() );
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m_flNodeSpringDistsSqr[i] = m_flSpringDistSqr / NumSprings();
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}
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}
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void CBaseRopePhysics::Restart()
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{
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m_Physics.Init( 1.0 / 50 );
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}
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void CBaseRopePhysics::ResetSpringLength( float flSpringDist )
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{
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m_flSpringDist = max( flSpringDist, 0.f );
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m_flSpringDistSqr = m_flSpringDist * m_flSpringDist;
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for( int i=0; i < NumSprings(); i++ )
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{
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m_flNodeSpringDistsSqr[i] = m_flSpringDistSqr / NumSprings();
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}
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}
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float CBaseRopePhysics::GetSpringLength() const
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{
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return m_flSpringDist;
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}
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void CBaseRopePhysics::ResetNodeSpringLength( int iStartNode, float flSpringDist )
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{
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m_flNodeSpringDistsSqr[iStartNode] = flSpringDist * flSpringDist;
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}
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void CBaseRopePhysics::SetupSimulation( float flSpringDist, CSimplePhysics::IHelper *pDelegate )
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{
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ResetSpringLength( flSpringDist );
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SetDelegate( pDelegate );
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}
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void CBaseRopePhysics::SetDelegate( CSimplePhysics::IHelper *pDelegate )
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{
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m_pDelegate = pDelegate;
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}
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void CBaseRopePhysics::Simulate( float dt )
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{
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static float flEnergy = 0.98;
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m_Physics.Simulate( m_pNodes, m_nNodes, this, dt, flEnergy );
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}
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void CBaseRopePhysics::GetNodeForces( CSimplePhysics::CNode *pNodes, int iNode, Vector *pAccel )
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{
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if( m_pDelegate )
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m_pDelegate->GetNodeForces( pNodes, iNode, pAccel );
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else
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pAccel->Init( 0, 0, 0 );
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}
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void CBaseRopePhysics::ApplyConstraints( CSimplePhysics::CNode *pNodes, int nNodes )
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{
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// Handle springs..
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//
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// Iterate multiple times here. If we don't, then gravity tends to
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// win over the constraint solver and it's impossible to get straight ropes.
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static int nIterations = 3;
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for( int iIteration=0; iIteration < nIterations; iIteration++ )
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{
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for( int i=0; i < NumSprings(); i++ )
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{
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CRopeSpring *s = &m_pSprings[i];
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Vector vTo = *s->m_pNode1 - *s->m_pNode2;
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float flDistSqr = vTo.LengthSqr();
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// If we don't have an overall spring distance, see if we have a per-node one
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float flSpringDist = m_flSpringDistSqr;
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if ( !flSpringDist )
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{
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// TODO: This still isn't enough. Ropes with different spring lengths
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// per-node will oscillate forever.
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flSpringDist = m_flNodeSpringDistsSqr[i];
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}
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if( flDistSqr > flSpringDist )
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{
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float flDist = (float)sqrt( flDistSqr );
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vTo *= 1 - (m_flSpringDist / flDist);
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*s->m_pNode1 -= vTo * 0.5f;
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*s->m_pNode2 += vTo * 0.5f;
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}
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}
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if( m_pDelegate )
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m_pDelegate->ApplyConstraints( pNodes, nNodes );
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}
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}
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