VehicleEngine.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <Jolt/ObjectStream/SerializableObject.h>
#include <Jolt/Core/LinearCurve.h>
#include <Jolt/Core/StreamIn.h>
#include <Jolt/Core/StreamOut.h>
#include <Jolt/Physics/StateRecorder.h>
 
JPH_NAMESPACE_BEGIN
 
#ifdef JPH_DEBUG_RENDERER
    class DebugRenderer;
#endif // JPH_DEBUG_RENDERER

class JPH_EXPORT VehicleEngineSettings
{
    JPH_DECLARE_SERIALIZABLE_NON_VIRTUAL(JPH_EXPORT, VehicleEngineSettings)
 
public:
                            VehicleEngineSettings();

    void                    SaveBinaryState(StreamOut &inStream) const;

    void                    RestoreBinaryState(StreamIn &inStream);
 
    float                   mMaxTorque = 500.0f;                        
    float                   mMinRPM = 1000.0f;                          
    float                   mMaxRPM = 6000.0f;                          
    LinearCurve             mNormalizedTorque;                          
    float                   mInertia = 0.5f;                            
    float                   mAngularDamping = 0.2f;                     
};

class JPH_EXPORT VehicleEngine : public VehicleEngineSettings
{
public:
    static constexpr float  cAngularVelocityToRPM = 60.0f / (2.0f * JPH_PI);

    inline void             ClampRPM()                                  { mCurrentRPM = Clamp(mCurrentRPM, mMinRPM, mMaxRPM); }

    float                   GetCurrentRPM() const                       { return mCurrentRPM; }

    void                    SetCurrentRPM(float inRPM)                  { mCurrentRPM = inRPM; ClampRPM(); }

    inline float            GetAngularVelocity() const                  { return mCurrentRPM / cAngularVelocityToRPM; }

    float                   GetTorque(float inAcceleration) const       { return inAcceleration * mMaxTorque * mNormalizedTorque.GetValue(mCurrentRPM / mMaxRPM); }

    void                    ApplyTorque(float inTorque, float inDeltaTime);

    void                    ApplyDamping(float inDeltaTime);
 
#ifdef JPH_DEBUG_RENDERER
    // Function that converts RPM to an angle in radians for debugging purposes
    float                   ConvertRPMToAngle(float inRPM) const        { return (-0.75f + 1.5f * inRPM / mMaxRPM) * JPH_PI; }

    void                    DrawRPM(DebugRenderer *inRenderer, RVec3Arg inPosition, Vec3Arg inForward, Vec3Arg inUp, float inSize, float inShiftDownRPM, float inShiftUpRPM) const;
#endif // JPH_DEBUG_RENDERER

    bool                    AllowSleep() const                          { return mCurrentRPM <= 1.01f * mMinRPM; }

    void                    SaveState(StateRecorder &inStream) const;
    void                    RestoreState(StateRecorder &inStream);
 
private:
    float                   mCurrentRPM = mMinRPM;                      
};
 
JPH_NAMESPACE_END