aoBodyEntity.h

/*
ONLY FILE NEEDED TO INCLUDE
*/
#ifndef AOBODYENTITY_H
#define AOBODYENTITY_H
#include "aoEntity.h"

namespace ao
{
	namespace graphics
	{

		class BodyEntity:public BaseEntity
		{
		protected:
			double t;
			double c;
			double v;
			double m;
			double s;
		public:
			BodyEntity();
			virtual ~BodyEntity() {}

			//Functionality
			double  Velocity()const
			{
				return v;
			}
			void      SetVelocity(const double& new_Vel)
			{
				v = new_Vel;
			}

			double     Mass()const
			{
				return m;
			}

			//Vector3 Side()const{return m_Side;}

			double     Thrust()const
			{
				return t;
			}
			void      SetThrust(double new_thrust)
			{
				t = new_thrust;
			}

			double     DragCoefficient()const
			{
				return c;
			}
			void      SetDragCoefficient(double new_dragCoeffiecient)
			{
				c = new_dragCoeffiecient;
			}
			void      StepSimulation(double dt);
			void      StepSimulationAdaptive(double dt);
			void      StepSimulationImproved(double dt);
			void      StepSimulationRunge(double dt);
		};
		inline BodyEntity::BodyEntity()
		{
			s=0;
			t=0;
			v=0;
			c=0;
			m=0;
		}
		//Physic Stuffs
		//Eulers basic method
		inline void BodyEntity::StepSimulation(double dt)
		{
			//placeholders for calculations
			double F;
			double A;
			double V;
			double S;

			//calculate the total force
			F=(t-(c*v));

			//calculate acceleration
			A = F/m;

			//newVelocity
			V= v+A*dt;

			//update
			v=V;
			s=S;
		}
		inline void BodyEntity::StepSimulationAdaptive(double dt)
		{
			double F;
			double A;
			double V;
			double S;
			double V1;
			double V2;
			double DT;
			double ET;
			//
			double ETO;
			//take one step to estimate
			F=(t-(c*v));
			A = F/m;
			V1= v+A*dt;

			//take two steps to estimate a further approxomation
			F=(t-(c*v));
			A = F/m;
			V2= v+A*(dt/2);
			F=(t-(c*V2));
			A = F/m;
			V2= V2+A*(dt/2);
			//estimate the error difference
			ET=abs(V1-V2);
			//estiamte a new step size
			DT=dt*sqrt(ETO/ET);
			if(DT<dt)
			{
				//Smaller Step
				F=(t-(c*v));
				A = F/m;
				V=v+A*DT;
				S=s+V*DT;
			}
			else
			{
				//Original Step
				V=V1;
				S=s+V*dt;
			}
			v=V;
			s=S;
		}
		inline void BodyEntity::StepSimulationImproved(double dt)
		{
			//placeholders for calculations
			double F;
			double A;
			double V;
			double S;
			double K1;
			double K2;

			F=(t-(c*v));
			A = F/m;
			K1=dt*A;

			F=(t-(c*(v+K1)));
			A = F/m;
			K2=dt*A;

			V=v+(K1+K2)/2;
			S=s+V*dt;

			//update
			v=V;
			s=S;
		}
		inline void BodyEntity::StepSimulationRunge(double dt)
		{
			//placeholders for calculations
			double F;
			double A;
			double V;
			double S;
			double K1;
			double K2;
			double K3;
			double K4;

			F=(t-(c*v));
			A = F/m;
			K1=dt*A;

			F=(t-(c*(v+K1/2)));
			A = F/m;
			K2=dt*A;

			F=(t-(c*(v+K2/2)));
			A = F/m;
			K3=dt*A;

			F=(t-(c*(v+K3)));
			A = F/m;
			K4=dt*A;
			//
			V=v+(K1+2*K2 + 2*K3 + K4)/6;
			S=s+V*dt;

			//update
			v=V;
			s=S;
		}
	}
}
#endif