Bifrost 24fps

[Gary Jaeger]

Does anybody have any experience with Bifrost? I’m finding if my scene is set to 30fps, I can’t do the simplest of Bifrost simulations. Make a plane, Create Liquid. I don’t get an error, and it looks like it’s filling up the cache, but I don’t see anything. Doing the same at 24 fps works fine.

Also, if I leave my plane at y=0 I get //Warning: The bifrost diagnostic data could not be processed.

Gary Jaeger // Core Studio
249 Princeton Avenue
Half Moon Bay, CA 94019
650 728 7060
http://corestudio.com

[Luc-Eric Rousseau]

hello, I got this feedback from Kosta in QA:

>>>

Does anybody have any experience with Bifrost? I'm finding if my
scene is set to 30fps, I can't do the simplest of Bifrost simulations.
Make a plane, Create Liquid. I don't get an error, and it looks like
it's filling up the cache, but I don't see anything. Doing the same at
24 fps works fine.

>> This is not a bifrost bug but rather a bug in Maya. When you change your frame rate, the start of the playback range is also changed. In the case of 30fps, the start of the playback range gets set to 1.25. You must change this back to 1 and rewind to start of playback in order for bifrost to compute its initiation.

Also, if I leave my plane at y=0 I get //Warning: The bifrost
diagnostic data could not be processed.

>> This is a known Warning and should not cause any loss of functionality.

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[Gary Jaeger]

Thanks, appreciate it. I’m very familiar with frame 1.25 :) The only way I’ve gotten it to work is to make an empty 30fps scene, save it. quit. reopen the scene and start bifrosting. I’ll report it.

Gary Jaeger // Core Studio
249 Princeton Avenue
Half Moon Bay, CA 94019
650 728 7060
http://corestudio.com

[peter shipkov]

When i have to hop from 24 frame scene to 30 fps i usually do this:

  mc.currentUnit(time="film")
 
  sf = 1.0 (or 100, or 1000 - whatever is the standard in your studio)
  handle = 0 (most shots have in/out handles - usually 5 to 10 frames before/after the shot start/end frames)
  scale = 30.0/24.0
  offset = scale * (sf+handle) - (sf+handle)
  ef = scale * ef - offset
 
  mc.currentUnit(time="ntsc")
 
  mc.playbackOptions(min=sf, ast=sf, max=ef, aet=ef)

This obviously will require animation keys tweak otherwise they will cause things to move "too slow" in the 30 FPS space:
    for n in mc.ls(type="animCurve"):
        if mc.container(q=True, fc=n) == None:
            mc.select(n)
            try:  mc.keyframe(e=True, iub=True, r=True, o="over", tc=-offset)
            except:  print("WARNING: Cannot move keys: "+n)

Finally because alembic readers (in the scene, if any) will need touch too:
        l = mc.ls(type="AlembicNode")
        for n in l: mc.setAttr(n+".offset", -offset)

Using this approach you can align everything from existing 24 FPS scene to defined by you startup frame upon switching to 30 FPS. Very handy when the Game Studio guys come one week before you are delivering their game trailer or cinematic and say "btw, we decided that we want everything in 30 FPS, that shouldn't be a problem, right ?".

... crickets in the room ... :)

It would be great if Maya can do these simple manipulations without user intervention.