p.Chaos.ImmPhys.DeltaTimeCount
p.Chaos.ImmPhys.DeltaTimeCount
#Overview
name: p.Chaos.ImmPhys.DeltaTimeCount
This variable is created as a Console Variable (cvar).
- type:
Var - help:
The number of ticks over which the moving average is calculated
It is referenced in 3 C++ source files.
#Summary
#Usage in the C++ source code
The purpose of p.Chaos.ImmPhys.DeltaTimeCount is to control the number of ticks over which a moving average is calculated for the step time in the Chaos Immediate Physics simulation system.
This setting variable is primarily used in the Chaos physics engine, which is part of Unreal Engine’s physics simulation subsystem. Specifically, it’s used in the Immediate Physics module of Chaos, which is designed for scenarios requiring immediate, synchronous physics calculations.
The value of this variable is set through a console variable system, as evidenced by the FAutoConsoleVariableRef declaration. This allows developers to modify the value at runtime or through configuration files.
The associated variable ChaosImmediate_Evolution_DeltaTimeCount interacts directly with p.Chaos.ImmPhys.DeltaTimeCount. They share the same value, with ChaosImmediate_Evolution_DeltaTimeCount being the actual variable used in the code, while p.Chaos.ImmPhys.DeltaTimeCount is the console variable name used to set its value.
Developers should be aware that this variable affects the calculation of the rolling average step time in the physics simulation. A higher value will result in a more stable average over time, but might be slower to react to changes in performance or simulation complexity.
Best practices when using this variable include:
- Adjusting it based on the specific needs of your project. A higher value provides more stability but less responsiveness to changes.
- Monitoring its impact on performance and simulation accuracy.
- Considering the trade-off between smooth physics behavior and quick adaptation to changing conditions.
Regarding the associated variable ChaosImmediate_Evolution_DeltaTimeCount:
- Its purpose is to store the actual count of ticks used in the moving average calculation.
- It’s used directly in the FImplementation constructor of the ImmediatePhysics_Chaos namespace to initialize the MaxNumRollingAverageStepTimes member variable.
- The value is set by the console variable system and can be modified at runtime.
- Developers should be aware that changing this value will directly affect the behavior of the physics simulation, potentially impacting both performance and accuracy.
#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:46
Scope: file
Source code excerpt:
FAutoConsoleVariableRef CVarChaosImmPhysNumSteps(TEXT("p.Chaos.ImmPhys.NumSteps"), ChaosImmediate_Evolution_NumSteps, TEXT("Override num steps (if not zero)"));
FAutoConsoleVariableRef CVarChaosImmPhysInitialStepTime(TEXT("p.Chaos.ImmPhys.InitialStepTime"), ChaosImmediate_Evolution_InitialStepTime, TEXT("Initial step time (then calculated from rolling average)"));
FAutoConsoleVariableRef CVarChaosImmPhysDeltaTimeCount(TEXT("p.Chaos.ImmPhys.DeltaTimeCount"), ChaosImmediate_Evolution_DeltaTimeCount, TEXT("The number of ticks over which the moving average is calculated"));
FAutoConsoleVariableRef CVarChaosImmPhysPositionIterations(TEXT("p.Chaos.ImmPhys.PositionIterations"), ChaosImmediate_Evolution_PositionIterations, TEXT("Override number of position iteration loops in immediate physics (if >= 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysVelocityIterations(TEXT("p.Chaos.ImmPhys.VelocityIterations"), ChaosImmediate_Evolution_VelocityIterations, TEXT("Override number of velocity iteration loops in immediate physics (if >= 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysProjectionIterations(TEXT("p.Chaos.ImmPhys.ProjectionIterations"), ChaosImmediate_Evolution_ProjectionIterations, TEXT("Override number of projection iteration loops in immediate physics (if >= 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysDisableInactiveByIndex(TEXT("p.Chaos.ImmPhys.DisableInactiveByIndex"), ChaosImmediate_DisableInactiveByIndex, TEXT("Disable bodies that are no longer active based on the index, rather than just count."));
FAutoConsoleVariableRef CVarChaosImmPhysNumCollisionsPerBlock(TEXT("p.Chaos.ImmPhys.NumCollisionsPerBlock"), ChaosImmediate_Evolution_NumCollisionsPerBlock, TEXT("The number of collision in a block in the collision pool. Higher values give better cache efficieny but waste memory if you do not need that many"));
#Associated Variable and Callsites
This variable is associated with another variable named ChaosImmediate_Evolution_DeltaTimeCount. They share the same value. See the following C++ source code.
#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:37
Scope: file
Source code excerpt:
int32 ChaosImmediate_Evolution_NumSteps = 0;
Chaos::FRealSingle ChaosImmediate_Evolution_InitialStepTime = 0.033f;
int32 ChaosImmediate_Evolution_DeltaTimeCount = 100;
int32 ChaosImmediate_Evolution_PositionIterations = -1;
int32 ChaosImmediate_Evolution_VelocityIterations = -1;
int32 ChaosImmediate_Evolution_ProjectionIterations = -1;
int32 ChaosImmediate_DisableInactiveByIndex = 1;
int32 ChaosImmediate_Evolution_NumCollisionsPerBlock = 50;
FAutoConsoleVariableRef CVarChaosImmPhysStepTime(TEXT("p.Chaos.ImmPhys.StepTime"), ChaosImmediate_Evolution_StepTime, TEXT("Override step time (if not zero)"));
FAutoConsoleVariableRef CVarChaosImmPhysNumSteps(TEXT("p.Chaos.ImmPhys.NumSteps"), ChaosImmediate_Evolution_NumSteps, TEXT("Override num steps (if not zero)"));
FAutoConsoleVariableRef CVarChaosImmPhysInitialStepTime(TEXT("p.Chaos.ImmPhys.InitialStepTime"), ChaosImmediate_Evolution_InitialStepTime, TEXT("Initial step time (then calculated from rolling average)"));
FAutoConsoleVariableRef CVarChaosImmPhysDeltaTimeCount(TEXT("p.Chaos.ImmPhys.DeltaTimeCount"), ChaosImmediate_Evolution_DeltaTimeCount, TEXT("The number of ticks over which the moving average is calculated"));
FAutoConsoleVariableRef CVarChaosImmPhysPositionIterations(TEXT("p.Chaos.ImmPhys.PositionIterations"), ChaosImmediate_Evolution_PositionIterations, TEXT("Override number of position iteration loops in immediate physics (if >= 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysVelocityIterations(TEXT("p.Chaos.ImmPhys.VelocityIterations"), ChaosImmediate_Evolution_VelocityIterations, TEXT("Override number of velocity iteration loops in immediate physics (if >= 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysProjectionIterations(TEXT("p.Chaos.ImmPhys.ProjectionIterations"), ChaosImmediate_Evolution_ProjectionIterations, TEXT("Override number of projection iteration loops in immediate physics (if >= 0)"));
FAutoConsoleVariableRef CVarChaosImmPhysDisableInactiveByIndex(TEXT("p.Chaos.ImmPhys.DisableInactiveByIndex"), ChaosImmediate_DisableInactiveByIndex, TEXT("Disable bodies that are no longer active based on the index, rather than just count."));
FAutoConsoleVariableRef CVarChaosImmPhysNumCollisionsPerBlock(TEXT("p.Chaos.ImmPhys.NumCollisionsPerBlock"), ChaosImmediate_Evolution_NumCollisionsPerBlock, TEXT("The number of collision in a block in the collision pool. Higher values give better cache efficieny but waste memory if you do not need that many"));
#Loc: <Workspace>/Engine/Source/Runtime/Engine/Private/PhysicsEngine/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.cpp:288
Scope (from outer to inner):
file
namespace ImmediatePhysics_Chaos
function FImplementation
Source code excerpt:
, RollingAverageStepTime(ChaosImmediate_Evolution_InitialStepTime)
, NumRollingAverageStepTimes(1)
, MaxNumRollingAverageStepTimes(ChaosImmediate_Evolution_DeltaTimeCount)
, bActorsDirty(false)
{
Particles.GetParticleHandles().AddArray(&CollidedParticles);
Particles.GetParticleHandles().AddArray(&ParticleMaterials);
Particles.GetParticleHandles().AddArray(&PerParticleMaterials);
Particles.GetParticleHandles().AddArray(&ParticlePrevXs);