A Pencil document is organized in layers. There are currently four types of layers:
- bitmap image
- vector image
The Time Line window at the bottom of the screen shows the existing layers. By default, a new document contains a bitmap layer, a vector layer, and a camera layer. You can add and delete layers as you wish (using either the or buttons next to “Layers”, or the menu Layer).
The names of the layers can be changed to represent what you’ve put in each by double-clicking on the name of the layer in the timeline. A window will pop up, allowing you to edit the layer’s name. Click OK when you have changed it to the name you want and the new name will appear in the timeline.
Each layer has a track which enables you to change it as a function of time. This is done by inserting keys (the little gray rectangles) at selected frames in the track. “Keys” or keyframes in pencil mean that every unique image (frame) ever displayed is a key. In a paper based process, key drawings define the acting and then additional drawings are supplied just to fill in the spaces in-between and maintain a consistent object thanks to persistence of vision. While some drawings are designated as “keys” and others as “breakdowns” and “Inbetweens”, they’re all just drawings on paper – eventually copied onto celluloid and then painted, stacked and shot with a camera.
Pencil works much like that: every frame that appears in your animation is a cel that appears in the timeline. The community has a tendancy of calling them “keys” which can be confusing for some users; they are akin to the individual cels and automatically held until replaced. That is, if you have a 100-frame animation and a “key” on frame 5, that same key will show up on frames 6 through 100 unless you add another key to replace it on the timeline.
So if you have your keys in the traditional sense, the images that define your overall movement/acting, you create your in-betweens (and breakdowns) by adding new keys to the timeline and drawing them in.
To add or delete keys at a particular frame in a layer track, use the or buttons next to “Keys” (shortcut: type “return” to create a new frame). For image layers (ie bitmap and vector), each key corresponds to a different image. The sequence of these images creates an animation. The current frame is indicated by the red bar and can be changed by moving the red bar to scrub through your animation (or use the left and right arrows). To play the animation, use the controls in the time line. Note that you can loop the animation, as well as set the number of frames per seconds.