32. AutoSleep¶

AutoSleep is a functionality for putting bodies which are not moving (below a certain threshold) to sleep. This means that the solver will no longer take these objects into account, hence reducing the CPU usage substantially.

A body can be put to sleep if its absolute velocity/acceleration goes below a certain threshold. AutoSleep is enabled for the system with a call to:

agxSDK::SimulationRef simulation = new agxSDK::Simulation;
agx::AutoSleep *autoSleep = simulation->getDynamicsSystem()->getAutoSleep();
// Enable autosleep functionality
autoSleep->setEnable(true);

AutoSleep also has to be enabled for each body:

agx::RigidBodyRef body = new agx::RigidBody
body->getAutoSleepProperties()->setEnable(true); // Enable AutoSleep for this body

A body will be awaken if

Another non-sleeping body get into contact with its geometry
Another body attached by a constraint is awaken
Explicit awakened through an API call

A body can be explicitly awakened through a call to:

body->getAutoSleepProperties()->setSleeping( false );

32.1. Threshold¶

The acceleration, velocity and time threshold can be set globally for AutoSleep:

// When linear velocity goes below 0.3m/s it will be considered for sleeping
autoSleep->getThreshold()->setVelocity(0.3);

// When angular velocity goes below 0.1rad/s it will be considered for sleeping
autoSleep->getThreshold()->setAngularVelocity(0.1);

// When velocity AND acceleration has been below threshold for 0.7 seconds the body
// will fall to sleep
autoSleep->getThreshold()->setTime( 0.7 );

Or locally per body:

// Create an AutoSleepThreshold object and set the values
agx::AutoSleepThresholdRef t = new agx::AutoSleepThreshold;
t->setVelocity(0.1);
t->setAngularVelocity(0.1);
t->setTime(2.0);

// Attach it to a body
body->setAutoSleepThreshold( t );

// Several bodies can share the same AutoSleepThreshold
body2->setAutoSleepThreshold( t );