/** @param last May be null. */
private TrackEntry trackEntry(
int trackIndex, Animation animation, boolean loop, TrackEntry last) {
TrackEntry entry = trackEntryPool.obtain();
entry.trackIndex = trackIndex;
entry.animation = animation;
entry.loop = loop;
entry.eventThreshold = 0;
entry.attachmentThreshold = 0;
entry.drawOrderThreshold = 0;
entry.animationStart = 0;
entry.animationEnd = animation.getDuration();
entry.animationLast = -1;
entry.nextAnimationLast = -1;
entry.delay = 0;
entry.trackTime = 0;
entry.trackLast = -1;
entry.nextTrackLast = -1;
entry.trackEnd = Float.MAX_VALUE;
entry.timeScale = 1;
entry.alpha = 1;
entry.mixAlpha = 1;
entry.mixTime = 0;
entry.mixDuration = last == null ? 0 : data.getMix(last.animation, animation);
return entry;
}