Curious, why does playable.GetInputCount() return 0 for a non-MixerBehaviour?

Just spent a couple hours trying to figure out why using playable.GetInputCount() in ProcessFrame() was returning 0 regardless of how many clips I had in the track.

I was using a regular (non-Mixer) PlayableBehaviour (aka my Track did not have a CreateTrackMixer() function set up). I set up a MixerBehaviour and now in the MixerBehaviour's ProcessFrame() it correctly shows the input count.

Why is this? I don't need to do any mixing/blending for this Track. Isn't the GetInputCount() just supposed to return the number of clips on the track?

I'm just trying to better understand what is going on here, thanks for any help!

 

Thanks for the response! I think I'm understanding things better now.

Non-MixerBehavior:
-is a behavior that is per-clip, not per-track
-doesn't call ProcessFrame unless its clip is currently active

MixerBehavior:
-is a single behavior for the entire track
-calls ProcessFrame always, and has the InputCount information & weights


What I was trying to do was to 'trigger something happening' on the first frame that a clip was active. I achieved this with the MixerBehavior by keeping track of the weights for each of the clips (via the InputCount) and triggering the thing when the weight went from 0 to 1.

Is there a suggested way for doing this with the normal non-mixerBehaviors? I could simply have a "bool hasBeenTriggered" and then reference & set that when ProcessFrame is called, but I'm not sure how the hasBeenTriggered bool would get reset - lets say if I was just scrubbing the timeline back and forth or something like that, I'm not sure how the bool could get reset?

Thanks again for the help!

 

Perfect, thank you for the explanation!