HingeConstraint.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/Physics/Constraints/TwoBodyConstraint.h>
#include <Jolt/Physics/Constraints/MotorSettings.h>
#include <Jolt/Physics/Constraints/ConstraintPart/PointConstraintPart.h>
#include <Jolt/Physics/Constraints/ConstraintPart/HingeRotationConstraintPart.h>
#include <Jolt/Physics/Constraints/ConstraintPart/AngleConstraintPart.h>
 
JPH_NAMESPACE_BEGIN
 
class HingeConstraintSettings final : public TwoBodyConstraintSettings
{
public:
    JPH_DECLARE_SERIALIZABLE_VIRTUAL(HingeConstraintSettings)
 
    // See: ConstraintSettings::SaveBinaryState
    virtual void                SaveBinaryState(StreamOut &inStream) const override;
 
    virtual TwoBodyConstraint * Create(Body &inBody1, Body &inBody2) const override;
 
    EConstraintSpace            mSpace = EConstraintSpace::WorldSpace;
 
    RVec3                       mPoint1 = RVec3::sZero();
    Vec3                        mHingeAxis1 = Vec3::sAxisY();
    Vec3                        mNormalAxis1 = Vec3::sAxisX();
    
    RVec3                       mPoint2 = RVec3::sZero();
    Vec3                        mHingeAxis2 = Vec3::sAxisY();
    Vec3                        mNormalAxis2 = Vec3::sAxisX();
    
    float                       mLimitsMin = -JPH_PI;
    float                       mLimitsMax = JPH_PI;
 
    float                       mMaxFrictionTorque = 0.0f;
 
    MotorSettings               mMotorSettings;
 
protected:
    // See: ConstraintSettings::RestoreBinaryState
    virtual void                RestoreBinaryState(StreamIn &inStream) override;
};
 
class HingeConstraint final : public TwoBodyConstraint
{
public:
    JPH_OVERRIDE_NEW_DELETE
 
                                HingeConstraint(Body &inBody1, Body &inBody2, const HingeConstraintSettings &inSettings);
 
    // Generic interface of a constraint
    virtual EConstraintSubType  GetSubType() const override                             { return EConstraintSubType::Hinge; }
    virtual void                NotifyShapeChanged(const BodyID &inBodyID, Vec3Arg inDeltaCOM) override;
    virtual void                SetupVelocityConstraint(float inDeltaTime) override;
    virtual void                WarmStartVelocityConstraint(float inWarmStartImpulseRatio) override;
    virtual bool                SolveVelocityConstraint(float inDeltaTime) override;
    virtual bool                SolvePositionConstraint(float inDeltaTime, float inBaumgarte) override;
#ifdef JPH_DEBUG_RENDERER
    virtual void                DrawConstraint(DebugRenderer *inRenderer) const override;
    virtual void                DrawConstraintLimits(DebugRenderer *inRenderer) const override;
#endif // JPH_DEBUG_RENDERER
    virtual void                SaveState(StateRecorder &inStream) const override;
    virtual void                RestoreState(StateRecorder &inStream) override;
    virtual Ref<ConstraintSettings> GetConstraintSettings() const override;
 
    // See: TwoBodyConstraint
    virtual Mat44               GetConstraintToBody1Matrix() const override;
    virtual Mat44               GetConstraintToBody2Matrix() const override;
 
    float                       GetCurrentAngle() const;
 
    // Friction control
    void                        SetMaxFrictionTorque(float inFrictionTorque)            { mMaxFrictionTorque = inFrictionTorque; }
    float                       GetMaxFrictionTorque() const                            { return mMaxFrictionTorque; }
 
    // Motor settings
    MotorSettings &             GetMotorSettings()                                      { return mMotorSettings; }
    const MotorSettings &       GetMotorSettings() const                                { return mMotorSettings; }
 
    // Motor controls
    void                        SetMotorState(EMotorState inState)                      { JPH_ASSERT(inState == EMotorState::Off || mMotorSettings.IsValid()); mMotorState = inState; }
    EMotorState                 GetMotorState() const                                   { return mMotorState; }
    void                        SetTargetAngularVelocity(float inAngularVelocity)       { mTargetAngularVelocity = inAngularVelocity; } 
    float                       GetTargetAngularVelocity() const                        { return mTargetAngularVelocity; }
    void                        SetTargetAngle(float inAngle)                           { mTargetAngle = mHasLimits? Clamp(inAngle, mLimitsMin, mLimitsMax) : inAngle; } 
    float                       GetTargetAngle() const                                  { return mTargetAngle; }
 
    void                        SetLimits(float inLimitsMin, float inLimitsMax);
    float                       GetLimitsMin() const                                    { return mLimitsMin; }
    float                       GetLimitsMax() const                                    { return mLimitsMax; }
    bool                        HasLimits() const                                       { return mHasLimits; }
 
    inline Vec3                 GetTotalLambdaPosition() const                          { return mPointConstraintPart.GetTotalLambda(); }
    inline Vector<2>            GetTotalLambdaRotation() const                          { return mRotationConstraintPart.GetTotalLambda(); }
    inline float                GetTotalLambdaRotationLimits() const                    { return mRotationLimitsConstraintPart.GetTotalLambda(); }
    inline float                GetTotalLambdaMotor() const                             { return mMotorConstraintPart.GetTotalLambda(); }
 
private:
    // Internal helper function to calculate the values below
    void                        CalculateA1AndTheta();
    void                        CalculateRotationLimitsConstraintProperties(float inDeltaTime);
    void                        CalculateMotorConstraintProperties(float inDeltaTime);
    inline float                GetSmallestAngleToLimit() const;
 
    // CONFIGURATION PROPERTIES FOLLOW
 
    // Local space constraint positions
    Vec3                        mLocalSpacePosition1;
    Vec3                        mLocalSpacePosition2;
 
    // Local space hinge directions
    Vec3                        mLocalSpaceHingeAxis1;
    Vec3                        mLocalSpaceHingeAxis2;
 
    // Local space normal direction (direction relative to which to draw constraint limits)
    Vec3                        mLocalSpaceNormalAxis1;
    Vec3                        mLocalSpaceNormalAxis2;
        
    // Inverse of initial relative orientation between bodies (which defines hinge angle = 0)
    Quat                        mInvInitialOrientation;
 
    // Hinge limits
    bool                        mHasLimits;
    float                       mLimitsMin;
    float                       mLimitsMax;
 
    // Friction
    float                       mMaxFrictionTorque;
 
    // Motor controls
    MotorSettings               mMotorSettings;
    EMotorState                 mMotorState = EMotorState::Off;
    float                       mTargetAngularVelocity = 0.0f;
    float                       mTargetAngle = 0.0f;
 
    // RUN TIME PROPERTIES FOLLOW
 
    // Current rotation around the hinge axis
    float                       mTheta = 0.0f;
    
    // World space hinge axis for body 1
    Vec3                        mA1;
 
    // The constraint parts
    PointConstraintPart         mPointConstraintPart;
    HingeRotationConstraintPart mRotationConstraintPart;
    AngleConstraintPart         mRotationLimitsConstraintPart;
    AngleConstraintPart         mMotorConstraintPart;
};
 
JPH_NAMESPACE_END