65 lines
1.8 KiB
C++
65 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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#ifndef SIMPLE_PHYSICS_H
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#define SIMPLE_PHYSICS_H
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#ifdef _WIN32
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#pragma once
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#endif
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#include "mathlib/vector.h"
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// CSimplePhysics is a framework for simplified physics simulation.
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// It simulates at a fixed timestep and uses the Verlet integrator.
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//
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// To use it, create your nodes and implement your constraints and
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// forces in an IHelper, then call Simulate each frame.
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// CSimplePhysics will figure out how many timesteps to run and will
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// provide predicted positions of things for you.
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class CSimplePhysics {
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public:
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class CNode {
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public:
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// Call this when initializing the nodes with their starting positions.
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void Init(const Vector &vPos) {
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m_vPos = m_vPrevPos = m_vPredicted = vPos;
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}
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Vector m_vPos; // At time t
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Vector m_vPrevPos; // At time t - m_flTimeStep
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Vector m_vPredicted; // Predicted position
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};
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class IHelper {
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public:
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virtual void GetNodeForces(CNode *pNodes, int iNode,
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Vector *pAccel) = 0;
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virtual void ApplyConstraints(CNode *pNodes, int nNodes) = 0;
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};
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public:
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CSimplePhysics();
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void Init(float flTimeStep);
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void Simulate(CNode *pNodes, int nNodes, IHelper *pHelper, float dt,
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float flDamp);
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private:
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double GetCurTime() { return m_flTimeStep * m_iCurTimeStep; }
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private:
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double m_flPredictedTime; // (GetCurTime()-m_flTimeStep) <=
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// m_flPredictedTime <= GetCurTime()
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int m_iCurTimeStep;
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float m_flTimeStep;
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float m_flTimeStepMul; // dt*dt*0.5
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};
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#endif // SIMPLE_PHYSICS_H
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