-
Using current time with expressions
Hi all
I’m attempting to trigger a sequence playback using sample image. I can drive the sequence directly with the colour that is currently under it frame by frame (ie if it’s black it’s frame 0, mid grey is half way, white is the last frame etc.) But I would like to trigger the playback from the beginning, at the correct frame rate when a certain value is under it on the control layer.
So I wrote an if else statement that triggers playback by adding the timeremap value to time,but obviously that makes the video sequence jump to that frame (if it’s triggered at frame 50, it jumps to frame 50 of the sequence).
So, my question is, can I get the current time value when the correct colour is detected, so I can subtract it from the timeremap value figure, before adding it to time?
Did that make sense? Apologies if not ?
Or is there a better way to trigger video playback with an image value?
Thanks
Matt
Visual tinkerer and easily distracted admirer of all things shiny! – writer – animator – digital artist
-
2 Replies
-
The problem is that expressions have no memory, so you can’t keep track of when an event like that happens. What you could do is check if the sampleImage() result is currently above the threshold, and if so, then you can have the the expression go backwards in time, frame by frame, (using sampleImage’s time parameter) to find the frame where the value went from below the threshold to above the threshold. From that you can calculate how long ago that happened, and how far you should be into the time remapping. Tricky, but do-able.
Dan
-
Hi Dan
many thanks for the super prompt response as ever.
Wow, it seems very computationally expensive, especially if we have a number of these objects triggering and a long comp duration.
I will have a play and see if my machine explodes : )
many thanks for the info.
cheers
Matt
Visual tinkerer and easily distracted admirer of all things shiny! – writer – animator – digital artist
Reply to this Discussion! Login or Sign Up