p.Chaos.ImmPhys.Joint.LinearProjection

p.Chaos.ImmPhys.Joint.LinearProjection

#Overview

name: p.Chaos.ImmPhys.Joint.LinearProjection

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.LinearProjection is to override the linear projection amount for 6 degrees of freedom (6DoF) joints in the Chaos physics engine’s immediate mode simulation.

This setting variable is part of the Chaos physics engine, specifically within the immediate physics simulation module. It is used in the ImmediatePhysicsChaos subsystem of Unreal Engine 5.

The value of this variable is set through the console variable system using FAutoConsoleVariableRef. It’s associated with the ChaosImmediate_Joint_LinearProjection variable, which is initially set to -1.0f.

The ChaosImmediate_Joint_LinearProjection variable interacts with other joint-related variables such as AngularProjection, ShockPropagation, Stiffness, and various soft constraint parameters. These variables are used together to fine-tune the behavior of joints in the physics simulation.

Developers must be aware that this variable only takes effect when its value is greater than or equal to zero. If the value is negative, it won’t override the default linear projection amount for the joints.

Best practices when using this variable include:

  1. Only modify it if you need to fine-tune joint behavior in the immediate physics simulation.
  2. Use values greater than or equal to zero to activate the override.
  3. Test thoroughly after modifying this value, as it can significantly impact joint stability and performance.

Regarding the associated variable ChaosImmediate_Joint_LinearProjection:

The purpose of ChaosImmediate_Joint_LinearProjection is to store the actual value used for linear projection in the immediate physics simulation.

This variable is used directly in the Chaos physics engine’s immediate mode simulation, specifically in the FSimulation::Simulate function.

The value of this variable is set either through the console variable system or programmatically in the code.

It interacts with other joint-related variables in the JointsSettings struct, which is used to configure joint behavior in the simulation.

Developers should be aware that this variable’s initial value is -1.0f, which means it won’t override the default linear projection amount unless changed.

Best practices for using this variable include:

  1. Modify it through the console variable system for easier tweaking during runtime.
  2. Consider the impact on overall joint behavior when changing this value, as it works in conjunction with other joint settings.
  3. Use it in conjunction with other joint parameters to achieve the desired physics behavior in your simulation.

#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:121

Scope: file

Source code excerpt:

FAutoConsoleVariableRef CVarChaosImmPhysJointEnableSwingLimits(TEXT("p.Chaos.ImmPhys.Joint.EnableSwingLimits"), ChaosImmediate_Joint_EnableSwingLimits, TEXT("EnableSwingLimits."));
FAutoConsoleVariableRef CVarChaosImmPhysJointEnableDrives(TEXT("p.Chaos.ImmPhys.Joint.EnableDrives"), ChaosImmediate_Joint_EnableDrives, TEXT("EnableDrives."));
FAutoConsoleVariableRef CVarChaosImmPhysJointLinearProjection(TEXT("p.Chaos.ImmPhys.Joint.LinearProjection"), ChaosImmediate_Joint_LinearProjection, TEXT("6Dof joint projection amount override (if >= 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointAngularProjection(TEXT("p.Chaos.ImmPhys.Joint.AngularProjection"), ChaosImmediate_Joint_AngularProjection, TEXT("6Dof joint projection amount override (if >= 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointShockPropagation(TEXT("p.Chaos.ImmPhys.Joint.ShockPropagation"), ChaosImmediate_Joint_ShockPropagation, TEXT("6Dof joint shock propagation override (if >= 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointStiffness(TEXT("p.Chaos.ImmPhys.Joint.Stiffness"), ChaosImmediate_Joint_Stiffness, TEXT("6Dof joint stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftLinearStiffness(TEXT("p.Chaos.ImmPhys.Joint.SoftLinearStiffness"), ChaosImmediate_Joint_SoftLinearStiffness, TEXT("6Dof joint soft linear stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftTwistStiffness(TEXT("p.Chaos.ImmPhys.Joint.SoftTwistStiffness"), ChaosImmediate_Joint_SoftTwistStiffness, TEXT("6Dof joint SoftTwist stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftTwistDamping(TEXT("p.Chaos.ImmPhys.Joint.SoftTwistDamping"), ChaosImmediate_Joint_SoftTwistDamping, TEXT("6Dof joint SoftTwist damping override (if > 0)."));

#Associated Variable and Callsites

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

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:97

Scope: file

Source code excerpt:

int32 ChaosImmediate_Joint_EnableSwingLimits = 1;
int32 ChaosImmediate_Joint_EnableDrives = 1;
Chaos::FRealSingle ChaosImmediate_Joint_LinearProjection = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_AngularProjection = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_ShockPropagation = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_Stiffness = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_SoftLinearStiffness = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_SoftTwistStiffness = -1.0f;
Chaos::FRealSingle ChaosImmediate_Joint_SoftTwistDamping = -1.0f;

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:121

Scope: file

Source code excerpt:

FAutoConsoleVariableRef CVarChaosImmPhysJointEnableSwingLimits(TEXT("p.Chaos.ImmPhys.Joint.EnableSwingLimits"), ChaosImmediate_Joint_EnableSwingLimits, TEXT("EnableSwingLimits."));
FAutoConsoleVariableRef CVarChaosImmPhysJointEnableDrives(TEXT("p.Chaos.ImmPhys.Joint.EnableDrives"), ChaosImmediate_Joint_EnableDrives, TEXT("EnableDrives."));
FAutoConsoleVariableRef CVarChaosImmPhysJointLinearProjection(TEXT("p.Chaos.ImmPhys.Joint.LinearProjection"), ChaosImmediate_Joint_LinearProjection, TEXT("6Dof joint projection amount override (if >= 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointAngularProjection(TEXT("p.Chaos.ImmPhys.Joint.AngularProjection"), ChaosImmediate_Joint_AngularProjection, TEXT("6Dof joint projection amount override (if >= 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointShockPropagation(TEXT("p.Chaos.ImmPhys.Joint.ShockPropagation"), ChaosImmediate_Joint_ShockPropagation, TEXT("6Dof joint shock propagation override (if >= 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointStiffness(TEXT("p.Chaos.ImmPhys.Joint.Stiffness"), ChaosImmediate_Joint_Stiffness, TEXT("6Dof joint stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftLinearStiffness(TEXT("p.Chaos.ImmPhys.Joint.SoftLinearStiffness"), ChaosImmediate_Joint_SoftLinearStiffness, TEXT("6Dof joint soft linear stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftTwistStiffness(TEXT("p.Chaos.ImmPhys.Joint.SoftTwistStiffness"), ChaosImmediate_Joint_SoftTwistStiffness, TEXT("6Dof joint SoftTwist stiffness override (if > 0)."));
FAutoConsoleVariableRef CVarChaosImmPhysJointSoftTwistDamping(TEXT("p.Chaos.ImmPhys.Joint.SoftTwistDamping"), ChaosImmediate_Joint_SoftTwistDamping, TEXT("6Dof joint SoftTwist damping override (if > 0)."));

#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:883

Scope (from outer to inner):

file
namespace    ImmediatePhysics_Chaos
function     void FSimulation::Simulate

Source code excerpt:

			JointsSettings.TwistStiffnessOverride = ChaosImmediate_Joint_Stiffness;
			JointsSettings.SwingStiffnessOverride = ChaosImmediate_Joint_Stiffness;
			JointsSettings.LinearProjectionOverride = ChaosImmediate_Joint_LinearProjection;
			JointsSettings.AngularProjectionOverride = ChaosImmediate_Joint_AngularProjection;
			JointsSettings.ShockPropagationOverride = ChaosImmediate_Joint_ShockPropagation;
			JointsSettings.SoftLinearStiffnessOverride = ChaosImmediate_Joint_SoftLinearStiffness;
			JointsSettings.SoftTwistStiffnessOverride = ChaosImmediate_Joint_SoftTwistStiffness;
			JointsSettings.SoftTwistDampingOverride = ChaosImmediate_Joint_SoftTwistDamping;
			JointsSettings.SoftSwingStiffnessOverride = ChaosImmediate_Joint_SoftSwingStiffness;