AerodynamicsSystem.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Math/MathFwd.h"
#include "VehicleSystemTemplate.h"
#include "VehicleUtility.h"
 
#if VEHICLE_DEBUGGING_ENABLED
UE_DISABLE_OPTIMIZATION
#endif
 
namespace Chaos
{
    /*
    *   Simple Aerodynamics - calculates drag and down-force/lift-force for a given speed
    *
    *   #todo: Add options for drafting/Slipstreaming effect
    *   #todo: Proper defaults
    */
 
    struct CHAOSVEHICLESCORE_API FSimpleAerodynamicsConfig
    {
        FSimpleAerodynamicsConfig()
            : AreaMetresSquared(2.0f)
            , DragCoefficient(0.1f)
            , DownforceCoefficient(0.1f)
        {
 
        }
 
    //  FVector Offet;              // local offset relative to CM
        float AreaMetresSquared;    // [meters squared]
        float DragCoefficient;      // always positive
        float DownforceCoefficient; // positive for downforce, negative lift
                                
    };
 
 
    class CHAOSVEHICLESCORE_API FSimpleAerodynamicsSim : public TVehicleSystem<FSimpleAerodynamicsConfig>
    {
    public:
        FSimpleAerodynamicsSim(const FSimpleAerodynamicsConfig* SetupIn);
 
        void SetDensityOfMedium(float DensityIn)
        {
            DensityOfMedium = DensityIn;
        }
 
        void SetDragCoefficient(float InCoeffient)
        {
            DragCoefficient = InCoeffient;
            EffectiveDragConstant = 0.5f * Setup().AreaMetresSquared * DragCoefficient;
        }
 
        void SetDownforceCoefficient(float InCoeffient)
        {
            DownforceCoefficient = InCoeffient;
            EffectiveLiftConstant = 0.5f * Setup().AreaMetresSquared * DownforceCoefficient;
        }
 
        float GetDragForceFromVelocity(float VelocityIn)
        {
            return -EffectiveDragConstant * DensityOfMedium * VelocityIn * VelocityIn;
        }
 
        float GetLiftForceFromVelocity(float VelocityIn)
        {
            return -EffectiveLiftConstant * DensityOfMedium * VelocityIn * VelocityIn;
        }
 
        FVector GetCombinedForces(float VelocityIn);
 
    protected:
        float DownforceCoefficient;
        float DragCoefficient;
        float DensityOfMedium;
        float EffectiveDragConstant;
        float EffectiveLiftConstant;
 
    };
 
} // namespace Chaos
 
#if VEHICLE_DEBUGGING_ENABLED
UE_ENABLE_OPTIMIZATION
#endif