Controlling an existing animation within a 3D scene using JavaScript is possible, though there are only limited functions available - you can select an animation from the scene and start/pause playback, but to change the speed, detect time ranges. etc., you must write all the code yourself (not trivial). See the Acrobat X SDK documentation, in particular scene.activateAnimation() and the TimeEventHander() objects. TimeEvents are fired in the context of the active animation's playback, not absolute time - so you can look for a value and stop the animation with runtime.pause() when it's reached.
Acrobat X has no inbuilt tools to create or modify animations within a 3D scene, for that you need external software or the Tetra4D plugins.
Acrobat X has no inbuilt tools to create or modify animations within a 3D scene, for that you need external software or the Tetra4D plugins.