Manpages - rtcJoinCommitScene.3embree3

  rtcJoinCommitScene - commits the scene from multiple threads

  #include <embree3/rtcore.h>

  void rtcJoinCommitScene(RTCScene scene);

The rtcJoinCommitScene function commits all changes for the specified scene (scene argument). The scene commit internally triggers building of a spatial acceleration structure for the scene. Ray queries can be performed after scene changes got properly committed.

The rtcJoinCommitScene function can get called from multiple user threads which will all cooperate in the build operation. All threads calling into this function will return from rtcJoinCommitScene after the scene commit is finished. All threads must consistently call rtcJoinCommitScene and not rtcCommitScene.

In contrast to the rtcCommitScene function, the rtcJoinCommitScene function can be called from multiple user threads, while the rtcCommitScene can only get called from multiple TBB worker threads when used concurrently. For optimal performance we strongly recommend using TBB inside the application together with the rtcCommitScene function and to avoid using the rtcJoinCommitScene function.

The rtcJoinCommitScene feature allows a flexible way to lazily create hierarchies during rendering. A thread reaching a not-yet-constructed sub-scene of a two-level scene can generate the sub-scene geometry and call rtcJoinCommitScene on that just generated scene. During construction, further threads reaching the not-yet-built scene can join the build operation by also invoking rtcJoinCommitScene. A thread that calls rtcJoinCommitScene after the build finishes will directly return from the rtcJoinCommitScene call.

Multiple scene commit operations on different scenes can be running at the same time, hence it is possible to commit many small scenes in parallel, distributing the commits to many threads.

When using Embree with the Intel® Threading Building Blocks (which is the default), threads that call rtcJoinCommitScene will join the build operation, but other TBB worker threads might also participate in the build. To avoid thread oversubscription, we recommend using TBB also inside the application. Further, the join mode only works properly starting with TBB v4.4 Update 1. For earlier TBB versions, threads that call rtcJoinCommitScene to join a running build will just trigger the build and wait for the build to finish. Further, old TBB versions with TBB_INTERFACE_VERSION_MAJOR < 8 do not support rtcJoinCommitScene, and invoking this function will result in an error.

When using Embree with the internal tasking system, only threads that call rtcJoinCommitScene will perform the build operation, and no additional worker threads will be scheduled.

When using Embree with the Parallel Patterns Library (PPL), rtcJoinCommitScene is not supported and calling that function will result in an error.

To detect whether rtcJoinCommitScene is supported, use the rtcGetDeviceProperty function.

On failure an error code is set that can be queried using rtcGetDeviceError.

[rtcCommitScene], [rtcGetDeviceProperty]