RotoPaint - Nuke 101: Professional Compositing and Visual Effects - page 247

Figure 6.7. Can you tell I didn't even use a tablet to draw this?
5. Switch back to the RotoPaint tab.
6. Move one frame forward in the Timebar.
All the strokes you drew have disappeared. The Tool Settings bar now allows you to spe-
cifythelengthofstrokesusingthelastunlabeleddrop-downmenuontheright.Themenu
shows Single, meaning just a single-frame stroke. The good thing is, though, that you can
change stroke time lengths after you draw them.
Editing strokes
Inatree-basedcompositingapplication—andinNukespecifically—creatingpaintstrokes
is done with timing in mind. Sometimes you need to create a stroke that will last only a
frame, sometimes it's an infinite stroke (one that lasts throughout the whole length of the
composition and beyond). Sometimes you need a stroke to start at a specific frame and go
all the way to the end of the composition, and sometimes you just need it to appear in a
specific range.