The Grease Pencil

The Grease Pencil is a very simple tool in Blender that has many useful applications.  In its simplest form, it just provides the ability to draw in the 3D View.  However, this can be useful for explaining, storyboarding, quick animating, etc.  

We'll go through some of the features and some of these applications.

The Grease Pencil is always available in the Tools [T] menu on the left side of the 3D View.  To begin drawing at any point, any of the four modes: Draw, Line, Poly and Erase can be selected.  This will allow you to make one stroke.  If Use Sketching Session is selected, then a new layer will be created and you can make many strokes.

The commands for these modes are:

• Draw: D + LMB
• Line: Ctrl + D + LMB
• Poly: Ctrl + D + RMB
• Erase: D + RMB
• Exit: Esc

In the Properties Panel [N], to the right of the 3D View, are more parameters that can be adjusted.  When you select Use Sketching Session, a new layer is created.  In this case, it is called GP_Layer by default.

In the panel above, note that there are four different Drawing Settings.  These each affect the scene differently as will be shown below.  Four different marks were made, each with a different drawing setting.

Note that when the scene is moved, their characteristics are revealed.

• Cursor/Stroke:  Draws within the scene, but not on meshes.
• Surface:  Projected onto mesh in the scene (does not move with mesh though)
• View:  Static in the 3D view

Note that X-Ray is turned off so that's why you can't see the lines through the mesh.

Finally, another common method for employing the Grease Pencil is to sketch out a simple animation.  The drawings created are all tied to specific frames.  So each frame can have its own drawing.  These can be animated if the timeline is played.  As well, to facilitate animating, the Onion Skinning option is available in the Properties Panel, which, as shown below, allows you to see lighter traces of the previous frames (also designated in the panel).