p.Chaos.ImmPhys.Joint.LinearDriveStiffness

p.Chaos.ImmPhys.Joint.LinearDriveStiffness

#Overview

name: p.Chaos.ImmPhys.Joint.LinearDriveStiffness

This variable is created as a Console Variable (cvar).

It is referenced in 4 C++ source files.

#Summary

#Usage in the C++ source code

The purpose of p.Chaos.ImmPhys.Joint.LinearDriveStiffness is to provide an override for the linear drive stiffness of 6 degrees of freedom (6DoF) joints in the Chaos Immediate Physics simulation system within Unreal Engine 5.

This setting variable is utilized by the Chaos physics engine, specifically within the Immediate Physics simulation module. It’s part of the physics engine subsystem in Unreal Engine 5.

The value of this variable is set through a console variable (CVar) system, allowing runtime modification. It’s initialized with a default value of -1.0f and can be changed during runtime or through configuration files.

The associated variable ChaosImmediate_Joint_LinearDriveStiffness directly interacts with p.Chaos.ImmPhys.Joint.LinearDriveStiffness. They share the same value, with the CVar acting as an interface for external control.

Developers must be aware that this variable only takes effect when its value is greater than 0. If it’s less than or equal to 0, the default or pre-configured joint settings will be used instead.

Best practices when using this variable include:

  1. Use it for fine-tuning joint behavior in specific scenarios rather than as a global setting.
  2. Monitor its impact on overall simulation stability and performance.
  3. Consider using it in conjunction with other joint-related settings for comprehensive joint control.

Regarding the associated variable ChaosImmediate_Joint_LinearDriveStiffness:

Its purpose is to store the actual value used by the physics simulation for the linear drive stiffness of 6DoF joints.

This variable is used directly within the Chaos Immediate Physics simulation system, specifically in the FSimulation::Simulate function.

Its value is set either by the default initialization (-1.0f) or through the CVar system when p.Chaos.ImmPhys.Joint.LinearDriveStiffness is modified.

It interacts with the JointsSettings structure, specifically the LinearDriveStiffnessOverride field, directly influencing joint behavior in the physics simulation.

Developers should be aware that this variable acts as an override. When its value is greater than 0, it will supersede any per-joint linear drive stiffness settings.

Best practices include monitoring this variable’s value during runtime debugging and considering its impact on joint behavior when troubleshooting physics-related issues.

#References in C++ code

#Callsites

This variable is referenced in the following C++ source code:

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:130

Scope: file

Source code excerpt:

FAutoConsoleVariableRef CVarChaosImmPhysJointSoftSwingStiffness(TEXT("p.Chaos.ImmPhys.Joint.SoftSwingStiffness"), ChaosImmediate_Joint_SoftSwingStiffness, TEXT("6Dof joint SoftSwing stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftSwingDamping(TEXT("p.Chaos.ImmPhys.Joint.SoftSwingDamping"), ChaosImmediate_Joint_SoftSwingDamping, TEXT("6Dof joint SoftSwing damping override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointLinearDriveStiffness(TEXT("p.Chaos.ImmPhys.Joint.LinearDriveStiffness"), ChaosImmediate_Joint_LinearDriveStiffness, TEXT("6Dof joint drive stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointLinearDriveDamping(TEXT("p.Chaos.ImmPhys.Joint.LinearDriveDamping"), ChaosImmediate_Joint_LinearDriveDamping, TEXT("6Dof joint drive damping override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointAngularDriveStiffness(TEXT("p.Chaos.ImmPhys.Joint.AngularDriveStiffness"), ChaosImmediate_Joint_AngularDriveStiffness, TEXT("6Dof joint drive stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointAngularDriveDamping(TEXT("p.Chaos.ImmPhys.Joint.AngularDriveDamping"), ChaosImmediate_Joint_AngularDriveDamping, TEXT("6Dof joint drive damping override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointMinParentMassRatio(TEXT("p.Chaos.ImmPhys.Joint.MinParentMassRatio"), ChaosImmediate_Joint_MinParentMassRatio, TEXT("6Dof joint MinParentMassRatio (if > 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysJointMaxInertiaRatio(TEXT("p.Chaos.ImmPhys.Joint.MaxInertiaRatio"), ChaosImmediate_Joint_MaxInertiaRatio, TEXT("6Dof joint MaxInertiaRatio (if > 0)"));

#Associated Variable and Callsites

This variable is associated with another variable named ChaosImmediate_Joint_LinearDriveStiffness. They share the same value. See the following C++ source code.

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:106

Scope: file

Source code excerpt:

Chaos::FRealSingle ChaosImmediate_Joint_SoftSwingStiffness = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_SoftSwingDamping = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_LinearDriveStiffness = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_LinearDriveDamping = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_AngularDriveStiffness = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_AngularDriveDamping = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_MinParentMassRatio = 0.2f;
Chaos::FRealSingle ChaosImmediate_Joint_MaxInertiaRatio = 5.0f;
FAutoConsoleVariableRef CVarChaosImmPhysJointSwingTwistAngleTolerance(TEXT("p.Chaos.ImmPhys.Joint.SwingTwistAngleTolerance"), ChaosImmediate_Joint_SwingTwistAngleTolerance, TEXT("SwingTwistAngleTolerance."));

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:130

Scope: file

Source code excerpt:

FAutoConsoleVariableRef CVarChaosImmPhysJointSoftSwingStiffness(TEXT("p.Chaos.ImmPhys.Joint.SoftSwingStiffness"), ChaosImmediate_Joint_SoftSwingStiffness, TEXT("6Dof joint SoftSwing stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftSwingDamping(TEXT("p.Chaos.ImmPhys.Joint.SoftSwingDamping"), ChaosImmediate_Joint_SoftSwingDamping, TEXT("6Dof joint SoftSwing damping override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointLinearDriveStiffness(TEXT("p.Chaos.ImmPhys.Joint.LinearDriveStiffness"), ChaosImmediate_Joint_LinearDriveStiffness, TEXT("6Dof joint drive stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointLinearDriveDamping(TEXT("p.Chaos.ImmPhys.Joint.LinearDriveDamping"), ChaosImmediate_Joint_LinearDriveDamping, TEXT("6Dof joint drive damping override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointAngularDriveStiffness(TEXT("p.Chaos.ImmPhys.Joint.AngularDriveStiffness"), ChaosImmediate_Joint_AngularDriveStiffness, TEXT("6Dof joint drive stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointAngularDriveDamping(TEXT("p.Chaos.ImmPhys.Joint.AngularDriveDamping"), ChaosImmediate_Joint_AngularDriveDamping, TEXT("6Dof joint drive damping override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointMinParentMassRatio(TEXT("p.Chaos.ImmPhys.Joint.MinParentMassRatio"), ChaosImmediate_Joint_MinParentMassRatio, TEXT("6Dof joint MinParentMassRatio (if > 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysJointMaxInertiaRatio(TEXT("p.Chaos.ImmPhys.Joint.MaxInertiaRatio"), ChaosImmediate_Joint_MaxInertiaRatio, TEXT("6Dof joint MaxInertiaRatio (if > 0)"));

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:891

Scope (from outer to inner):

file
namespace    ImmediatePhysics_Chaos
function     void FSimulation::Simulate

Source code excerpt:

			JointsSettings.SoftSwingStiffnessOverride = ChaosImmediate_Joint_SoftSwingStiffness;
			JointsSettings.SoftSwingDampingOverride = ChaosImmediate_Joint_SoftSwingDamping;
			JointsSettings.LinearDriveStiffnessOverride = ChaosImmediate_Joint_LinearDriveStiffness;
			JointsSettings.LinearDriveDampingOverride = ChaosImmediate_Joint_LinearDriveDamping;
			JointsSettings.AngularDriveStiffnessOverride = ChaosImmediate_Joint_AngularDriveStiffness;
			JointsSettings.AngularDriveDampingOverride = ChaosImmediate_Joint_AngularDriveDamping;
			JointsSettings.NumShockPropagationIterations = ChaosImmediate_Joint_NumShockPropagationIterations;
			JointsSettings.bSortEnabled = true;
			Implementation->Joints.SetSettings(JointsSettings);