Open devtools console and watch the “total _syncActiveTargets called” log
Expected:
One goToFrame, or one regular animation frame emits one call to _syncActiveTargets per morphed mesh
Actual:
total _syncActiveTargets called: 14
Background:
Following Number of meshes significantly drop fps - #15 by kzhsw, where a profiler shows _syncActiveTargets costs most the cpu time, and the code shows every morph target update calls _syncActiveTargets to update all the morph target manager.
Call stack:
MorphTargetManager._syncActiveTargets
anonymous function in MorphTargetManager.addTarget
MorphTarget.onInfluenceChanged.notifyObservers
set MorphTarget.influence
RuntimeAnimation._setValue
For certain reasons, the base mesh also includes morph targets. There are therefore 8*2=16 targets in the scene. In frame 62, two targets have zero influence, leaving 14 non-zero targets, which is the number shown in the console.
Note that this is an asset-related issue, not a Babylon issue. The 3js glTF viewer also displays 16 targets:
Well, the thing is, _syncActiveTargets updates the whole MorphTargetManager, not a single target, so it should be called per animation frame per MorphTargetManager, instead of per MorphTarget, which makes a lot of redundant calls and increases cpu time.
