A flipbook lets you quickly review the motion and timing in an animation. It captures an image of the viewport at each frame and then plays the images as an animation. This is much faster than actually rendering the animation. You can also attach a sound file to test out how your shot is working with audio.

Houdini writes out the frames to your computer’s temporary storage directory, and the flipbook opens in MPlay. Use MPlay’s controls to view the flipbook.

You can block out a shot with a flipbook and edit the blocking by dragging keyframes in MPlay:

1. Set keyframes on all the parameters on a character/object.

2. click Render Flipbook at the bottom of the toolbar to the left of the viewport, and choose Flipbook with New Settings.

3. Turn on Scoped Channel Key Frames Only and Enable Block Editing.

4. The keyframes are highlighted on the MPlay timeline. You can select a range of keys by holding ⇧ Shift and dragging along the timeline. Then drag the selected range along the timeline to move the keys. This lets you change the timing of the blocked out images and preview the changes without creating a new flipbook.

5. When you are finished, choose Anim ▸ Export Blocking in MPlay to apply the edited timings to your scene.

desktop = hou.ui.curDesktop()
scene = desktop.paneTabOfType(hou.paneTabType.SceneViewer)

# Copy the viewer's current flipbook settings
flipbook_options = scene.flipbookSettings().stash()

# Change the settings however you need
# (for example, set the frame range and output filename)
flipbook_options.frameRange( (frame, frame) )
flipbook_options.output(filename)

# Generate the flipbook using the modified settings
scene.flipbook(scene.curViewport(), flip_options)

See hou.FlipbookSettings for information on the available settings.