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game/shared/sheetsimulator.h

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//=============================================================================//
+
+#ifndef SHEETSIMULATOR_H
+#define SHEETSIMULATOR_H
+#ifdef _WIN32
+#pragma once
+#endif
+
+#include "mathlib/mathlib.h"
+#include "mathlib/vector.h"
+#include "utlvector.h"
+
+
+// Uncomment this for client-side simulation
+//#define CLIENT_SIDE_SIMULATION 1
+
+//-----------------------------------------------------------------------------
+// Simulates a sheet
+//-----------------------------------------------------------------------------
+
+class CGameTrace;
+typedef CGameTrace trace_t;
+//struct trace_t;
+typedef void (*TraceLineFunc_t)(const Vector &vecStart, const Vector &vecEnd, 
+								unsigned int mask, int collisionGroup, trace_t *ptr);
+typedef void (*TraceHullFunc_t)(const Vector &vecStart, const Vector &vecEnd, 
+								const Vector &hullMin, const Vector &hullMax, 
+								unsigned int mask, int collisionGroup, trace_t *ptr);
+
+
+class CSheetSimulator
+{
+public:
+	CSheetSimulator( TraceLineFunc_t traceline, TraceHullFunc_t traceHull );
+	~CSheetSimulator();
+
+	void Init( int w, int h, int fixedPointCount );
+
+	// orientation
+	void SetPosition( const Vector& origin, const QAngle& angles );
+
+	// Makes a spring
+	void AddSpring( int p1, int p2, float restLength );
+	void AddFixedPointSpring( int fixedPoint, int p, float restLength );
+
+	// spring constants....
+	void SetPointSpringConstant( float constant );
+	void SetFixedSpringConstant( float constant );
+
+	// Used for both kinds of springs
+	void SetSpringDampConstant( float damp );
+	void SetViscousDrag( float drag );
+
+	// Sets the collision group
+	void SetCollisionGroup( int group );
+
+	// Sets the bounding box used for collision vs world
+	void SetBoundingBox( Vector& mins, Vector& maxs );
+
+	// Computes the bounding box
+	void ComputeBounds( Vector& mins, Vector& maxs );
+
+	// simulation
+	void Simulate( float dt );
+	void Simulate( float dt, int steps );
+
+	// get at the points
+	int NumHorizontal() const;
+	int NumVertical() const;
+	int PointCount() const;
+
+	// Fixed points
+	Vector& GetFixedPoint( int i );
+
+	// Point masses
+	const Vector& GetPoint( int x, int y ) const;
+	const Vector& GetPoint( int i ) const;
+
+	// For iterative collision detection
+	void DetectCollision( int i, float flOffset );
+	void InitPosition( int i );
+
+	// For offseting the control points
+	void SetControlPointOffset( const Vector& offset );
+
+	// Gravity
+	void SetGravityConstant( float g );
+	void AddGravityForce( int particle );
+
+protected:
+	struct Particle_t
+	{
+		float	m_Mass;
+		Vector	m_Position;
+		Vector	m_Velocity;
+		Vector	m_Force;
+		int		m_Collided;
+		int		m_CollisionPlane;
+		float	m_CollisionDist;
+	};
+
+	struct Spring_t
+	{
+		int m_Particle1;
+		int m_Particle2;
+		float m_RestLength;
+	};
+
+	inline int NumParticles() const
+	{
+		return m_HorizontalCount * m_VerticalCount; 
+	}
+
+	// simulator
+	void			EulerStep( float dt );
+	void			ComputeControlPoints();
+	void			ClearForces();
+	void			ComputeForces();
+	void			TestVertAgainstPlane( int vert, int plane, bool bFarTest = true );
+	void			SatisfyCollisionConstraints();
+	void			DetermineBestCollisionPlane( bool bFarTest = true );
+	void			ClampPointsToCollisionPlanes();
+
+	// How many particles horiz + vert?
+	int m_HorizontalCount;
+	int m_VerticalCount;
+
+	// The particles
+	Particle_t*	m_Particle;
+
+	// Output position after simulation
+	Vector*	m_OutputPosition;
+
+	// fixed points
+	int	m_FixedPointCount;
+	Vector* m_pFixedPoint;
+	Vector* m_ControlPoints;
+	
+	CUtlVector<Spring_t>	m_Springs;
+	CUtlVector<int>			m_Gravity;
+
+	// raycasting methods
+	TraceLineFunc_t		m_TraceLine;
+	TraceHullFunc_t		m_TraceHull;
+
+	// Spring constants
+	float	m_FixedSpringConstant;
+	float	m_PointSpringConstant;
+	float	m_DampConstant;
+	float	m_ViscousDrag;
+
+	// Collision group
+	int		m_CollisionGroup;
+
+	// position + orientation
+	Vector	m_Origin;
+	QAngle	m_Angles;
+
+	// collision box
+	Vector  m_FrustumBoxMin;
+	Vector	m_FrustumBoxMax;
+
+	// Collision planes
+	cplane_t*	m_pCollisionPlanes;
+	bool*		m_pValidCollisionPlane;
+
+	// Control point offset
+	Vector		m_ControlPointOffset;
+
+	// Gravity
+	float		m_GravityConstant;
+};
+
+
+//-----------------------------------------------------------------------------
+// Class to help dealing with the iterative computation
+//-----------------------------------------------------------------------------
+
+class CIterativeSheetSimulator : public CSheetSimulator
+{
+public:
+	CIterativeSheetSimulator( TraceLineFunc_t traceline, TraceHullFunc_t traceHull );
+
+	void BeginSimulation( float dt, int steps, int substeps, int collisionCount );
+
+	// Returns true if it just did a simulation step
+	bool Think( );
+	bool IsDone() const { return m_SimulationSteps == 0; }
+
+	int StepsRemaining( ) const { return m_SimulationSteps; }
+
+private:
+	CIterativeSheetSimulator( const CIterativeSheetSimulator & ); // not defined, not accessible
+
+	// Iterative collision detection 
+	void DetectCollisions( void );
+
+	float	m_TimeStep;
+	float	m_SubSteps;
+	char	m_TotalSteps;
+	char	m_SimulationSteps;
+	char	m_CollisionCount;
+	char	m_CurrentCollisionPt;
+	bool	m_InitialPass;
+};
+
+
+#endif // TF_SHIELD_SHARED_H