LiquidFun Files

Overview

The 1.0.0 release of LiquidFun introduces a number of new features to the API described below. Some of the highlights are: - Multiple particle systems. - New particle behaviors: barrier, static-pressure, and repulsive. - Particle lifetimes. - Detection of stuck particles. - The ability to apply forces and impulses to particles. - Java support via SWIG. - A host of new demos: inside the existing Testbed application, and gorgeous new "EyeCandy" demo for Android.

Users of 0.9.0 should carefully read through the API Modifications section to understand what they need to change to get their existing applications to work with the latest release of LiquidFun.

New Features

• Added option to substep particle simulation independently of b2World.
• Added barrier particles which can be used to prevent particle tunneling due to large particle velocities or simulation steps.
• Added static pressure particles to reduce compression of fluids.
• Added repulsive particles to separate particle groups from each other.
• Added support for multiple independent particle systems.
• Added option to create particles in an existing particle group.
• Added option to detect stuck particles.
• Added option to pause particle simulations. Paused simluations don't consume cycles in b2World::Step.
• Added option to enable a more strict check for Particle/Body interactions in cases where complex world geometry may cause false positive contacts.
• Added option to call a contact listener or filter on particle / fixture or particle / particle interactions.
• Added the ability to apply forces and impulses to particles.
• Added "EyeCandy" sample to demonstrate different particle rendering methods on Android.
• Added "Sparky", "Sandbox" and "Soup Stirrer" tests to the Testbed example to demonstrate particle and rigid body interaction.
• Added "Ramp", "Pointy", and "AntiPointy" tests to the Testbed example to illustrate the difference with strict contact checking.
• Added "Maxwell" test to the Testbed to demonstrate the direct modification of particle velocities.
• Added "Fracker" test to demonstrate particle viscous fluids and particle destruction callbacks.
• Added "Multiple Systems" test to the Testbed to demonstrate multiple particle systems.
• Added Java Native Interface support via SWIG. It covers a subset of the API.
• Added the ability to pass a list of shapes to be passed in for particle-group creation.

API Modifications

• b2Draw::e_particleBit flag now enables/disables b2World::DrawDebugData() drawing the particle system.

To render the particle system using b2World::DrawDebugData(), the b2Draw::e_particleBit flag must be set on the b2Draw object passed to b2World::SetDebugDraw(). It is possible to set flags on b2Draw objects using b2Draw::SetFlags().

Release 0.9.0 unconditionally called b2Draw::DrawParticles() from b2World::DrawDebugData(). - Building LiquidFun on Linux, using cmake -G"Unix Makefiles", now places output files in a build type sub-directory.

For example, the output executable of the Testbed example is now written to Box2D/Testbed/Release/Testbed when building using the Release configuration. - Multiple independent particle systems can now exist, each with its own physical coefficients. Previously, only one particle system existed, and it always existed. Use b2World::CreateParticleSystem to create particle systems, and b2World::DestroyParticleSystem to destroy them. - b2DestructionListener::SayGoodbye, b2QueryCallback::ReportParticle, and b2RayCastCallback::ReportParticle each now takes a b2ParticleSystem pointer as its first parameter. This change is necessary since multiple particle systems can now exist. - The particle system API has moved from b2World to b2ParticleSystem. For example, b2ParticleSystem::DestroyParticlesInShape replaces b2World::DestroyParticlesInShape. You can use b2World::CreateParticleSystem or b2World::GetParticleSystemList() to acquire references to b2ParticleSystem. - Removed "Particle" from many of the functions in the particle system API. The word is redundant now that the API is under b2ParticleSystem. The API now has the following naming convention: - Each function that takes a particle index or handle has a "Particle" component (e.g. "SetParticle"). - Each function that operates on the entire system has no "Particle" component (e.g. "SetRadius").

```
GetParticleMaxCount ==> GetMaxParticleCount
SetParticleMaxCount ==> SetMaxParticleCount
GetParticleDensity ==> GetDensity
SetParticleDensity ==> SetDensity
SetParticleGravityScale ==> SetGravityScale
GetParticleGravityScale ==> GetGravityScale
SetParticleDamping ==> SetDamping
GetParticleDamping ==> GetDamping
GetParticleStaticPressureIterations ==> GetStaticPressureIterations
SetParticleStaticPressureIterations ==> SetStaticPressureIterations
SetParticleRadius ==> SetRadius
GetParticleRadius ==> GetRadius
GetParticlePositionBuffer ==> GetPositionBuffer
GetParticlePositionBuffer ==> GetPositionBuffer
GetParticleVelocityBuffer ==> GetVelocityBuffer
GetParticleVelocityBuffer ==> GetVelocityBuffer
GetParticleColorBuffer ==> GetColorBuffer
GetParticleColorBuffer ==> GetColorBuffer
GetParticleGroupBuffer ==> GetGroupBuffer
GetParticleGroupBuffer ==> GetGroupBuffer
GetParticleUserDataBuffer ==> GetUserDataBuffer
GetParticleUserDataBuffer ==> GetUserDataBuffer
GetParticleFlagsBuffer ==> GetFlagsBuffer
SetParticleFlagsBuffer ==> SetFlagsBuffer
SetParticlePositionBuffer ==> SetPositionBuffer
SetParticleVelocityBuffer ==> SetVelocityBuffer
SetParticleColorBuffer ==> SetColorBuffer
SetParticleUserDataBuffer ==> SetUserDataBuffer
GetParticleContacts ==> GetContacts
GetParticleContactCount ==> GetContactCount
GetParticleBodyContacts ==> GetBodyContacts
GetParticleBodyContactCount ==> GetBodyContactCount
DestroyParticlesInGroup ==> DestroyParticles (moved to b2ParticleGroup)
```

• Renamed b2ParticleFlag b2DestructionListener to b2DestructionListenerParticle to be consistent with other particle flag names.
• Better particle-behavior stability.

Other Changes

• Integrated Box2D 2.3.0 release from Box2D revision 280.
• Reduced the size of particles in Testbed particle tests to be consistent with the size of rigid bodies.
• Improved damping force to prevent particle explosions.
• Fixed b2Timer bug that occurs when the usec component wraps.
• Added b2Stat to calculate min/max/mean of a set of samples, and integrated this functionality into Testbed to measure performance.
• Fixed memory leaks of large blocks allocated by b2BlockAllocator.
• Fixed incorrect stack-capacity calculation in b2VoronoiDiagram.
• Added operators to b2ParticleColor.
• Improved parameter and option selection in Testbed with the fullscreen UI.
• Cleaned up statistics display in Testbed.
• Fixed depth-buffer allocation when creating an empty particle group.
• Added build step to unit-test execution scripts.
• Added generation of code coverage report for unit-tests.
• Added a script to clean up temporary cmake files.
• Increased warning level and enabled conversion of warnings to errors.
• Added unit-test for b2IsValid().
• Added b2World::QueryShapeAABB() convenience function to query the world for objects in the AABB which encloses a shape.
• Inlined some simple b2ParticleSystem and b2ParticleGroup functions.
• Allowed particle systems to be culled from b2World::QueryAABB and b2World::RayCast.
• Added callbacks so an application can override b2Alloc() and b2Free() without modifying the library.
• Added valgrind support to unit-test runner on Linux / OSX.
• Added cygwin wrapper script for build.bat and build_android.bat on Windows.
• Added option to archive build artifacts from build scripts.
• Changed Android C++ runtime library to gnustl_static.