73 lines
1.8 KiB
C++
73 lines
1.8 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 "simple_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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CSimplePhysics::CSimplePhysics()
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{
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Init( 1.0f / 30.0f ); // default is 30 steps per second
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}
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void CSimplePhysics::Init( float flTimeStep )
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{
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m_flPredictedTime = 0;
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m_iCurTimeStep = 0;
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m_flTimeStep = flTimeStep;
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m_flTimeStepMul = m_flTimeStep*m_flTimeStep*0.5f;
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}
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void CSimplePhysics::Simulate(
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CSimplePhysics::CNode *pNodes,
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int nNodes,
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CSimplePhysics::IHelper *pHelper,
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float dt,
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float flDamp )
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{
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// Figure out how many time steps to run.
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m_flPredictedTime += dt;
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int newTimeStep = (int)ceil( m_flPredictedTime / m_flTimeStep );
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int nTimeSteps = newTimeStep - m_iCurTimeStep;
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for( int iTimeStep=0; iTimeStep < nTimeSteps; iTimeStep++ )
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{
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// Simulate everything..
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for( int iNode=0; iNode < nNodes; iNode++ )
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{
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CSimplePhysics::CNode *pNode = &pNodes[iNode];
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// Apply forces.
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Vector vAccel;
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pHelper->GetNodeForces( pNodes, iNode, &vAccel );
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Assert( vAccel.IsValid() );
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Vector vPrevPos = pNode->m_vPos;
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pNode->m_vPos = pNode->m_vPos + (pNode->m_vPos - pNode->m_vPrevPos) * flDamp + vAccel * m_flTimeStepMul;
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pNode->m_vPrevPos = vPrevPos;
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}
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// Apply constraints.
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pHelper->ApplyConstraints( pNodes, nNodes );
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}
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m_iCurTimeStep = newTimeStep;
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// Setup predicted positions.
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float flInterpolant = (m_flPredictedTime - (GetCurTime() - m_flTimeStep)) / m_flTimeStep;
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for( int iNode=0; iNode < nNodes; iNode++ )
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{
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CSimplePhysics::CNode *pNode = &pNodes[iNode];
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VectorLerp( pNode->m_vPrevPos, pNode->m_vPos, flInterpolant, pNode->m_vPredicted );
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}
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}
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