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XCEngine/engine/third_party/physx/source/physxvehicle/src/wheel/VhWheelFunctions.cpp

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// Redistribution and use in source and binary forms, with or without
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// Copyright (c) 2008-2025 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
#include "vehicle2/PxVehicleParams.h"
#include "vehicle2/suspension/PxVehicleSuspensionStates.h"
#include "vehicle2/tire/PxVehicleTireStates.h"
#include "vehicle2/wheel/PxVehicleWheelFunctions.h"
#include "vehicle2/wheel/PxVehicleWheelStates.h"
#include "vehicle2/wheel/PxVehicleWheelParams.h"
namespace physx
{
namespace vehicle2
{
void PxVehicleWheelRotationAngleUpdate
(const PxVehicleWheelParams& whlParams,
const PxVehicleWheelActuationState& actState, const PxVehicleSuspensionState& suspState, const PxVehicleTireSpeedState& trSpeedState,
const PxReal thresholdForwardSpeedForWheelAngleIntegration, const PxReal dt,
PxVehicleWheelRigidBody1dState& whlRigidBody1dState)
{
//At low vehicle forward speeds we have some numerical difficulties getting the
//wheel rotation speeds to be correct due to the tire model's difficulties at low vz.
//The solution is to blend between the rolling speed at the wheel and the wheel's actual rotation speed.
//If the wheel is
//(i) in the air or,
//(ii) under braking torque or,
//(iii) driven by a drive torque
//then always use the wheel's actual rotation speed.
//Just to be clear, this means we will blend when the wheel
//(i) is on the ground and
//(ii) has no brake applied and
//(iii) has no drive torque and
//(iv) is at low forward speed
const PxF32 jounce = suspState.jounce;
const bool isBrakeApplied = actState.isBrakeApplied;
const bool isDriveApplied = actState.isDriveApplied;
const PxF32 lngSpeed = trSpeedState.speedStates[PxVehicleTireDirectionModes::eLONGITUDINAL];
const PxF32 absLngSpeed = PxAbs(lngSpeed);
PxF32 wheelOmega = whlRigidBody1dState.rotationSpeed;
if (jounce > 0 && //(i) wheel touching ground
!isBrakeApplied && //(ii) no brake applied
!isDriveApplied && //(iii) no drive torque applied
(absLngSpeed < thresholdForwardSpeedForWheelAngleIntegration)) //(iv) low speed
{
const PxF32 wheelRadius = whlParams.radius;
const PxF32 alpha = absLngSpeed / thresholdForwardSpeedForWheelAngleIntegration;
wheelOmega = (lngSpeed/wheelRadius)*(1.0f - alpha) + wheelOmega * alpha;
}
whlRigidBody1dState.correctedRotationSpeed = wheelOmega;
//Integrate angle.
PxF32 newRotAngle = whlRigidBody1dState.rotationAngle + wheelOmega * dt;
//Clamp in range (-2*Pi,2*Pi)
newRotAngle = newRotAngle - (PxI32(newRotAngle / PxTwoPi) * PxTwoPi);
//Set the angle.
whlRigidBody1dState.rotationAngle = newRotAngle;
}
} //namespace vehicle2
} //namespace physx