The ability to draw in and/or on viewports using freehand strokes to form sketches and annotations has many benefits for collaborative communication and planning. This can be linked back to traditional 2D-workflows with pencil and paper, where rough 'guideline' sketches were often used for planning and also for communicating ideas quickly. It is often useful to be able to directly scribble on to a work in progress, instead of having to do so in a separate place (i.e. another part of the window, or even in a different application altogether).
The name "Grease Pencil" is derived in homage to the wax crayons/pencils that early CG Animators used to draw arcs and other planning notes on their CRT's with.
In addition to uses for animators in planning their poses and motion curves, Grease Pencil can also be useful in a number of scenarios, including but not limited to:
1. The first step when using Grease Pencil is to enable the display of Grease Pencil drawings for the relevant view. To do this, locate the 'Grease Pencil...' entry in the 'View' menu; click on the 'Use Grease Pencil' toggle that appears in the panel.
2. At this point, click on 'Add New Layer' to add a new layer to draw on. This step is not necessary when you are starting off a new drawing (as a new layer will automatically be created for you), unless you want to customise the line width, colour, and opacity before drawing. However, if you want to draw on a new layer once layers already exist, it is necessary to click on the button.
Additional Notes:
1. Enable the 'Draw Mode' toggle in top right-hand corner of the 'Grease Pencil' panel.
2. As for quickly drawing a few strokes, use the same mouse buttons to draw and erase, BUT without needing to use the modifier keys too (i.e. LMB to draw, RMB to erase).
The default settings for the sensitivity to mouse/stylus movement when drawing, have been set so that there shouldn't be too much jitter while still allowing for fine details to be made. However, sometimes these settings may not be appropriate, in which case, the defaults can be found in the User Preferences under Edit Methods.
Sketches are only relevant for the view/view-angle (referred to here as the 'drawing plane') that they were drawn at. There are several different options for how individual strokes (determined by the settings in use when the stroke was created) will be displayed.
Grease Pencil sketches are organised in layers, much like those you could find in the GIMP or Photoshop. These layers are not related to any of the other layer systems in Blender, and also do not have an upper limit on the maximum number of layers that can be used. Like the layers in the aforementioned apps, these layers can also be renamed, locked, hidden, and deleted.
Their main purpose is to collect together a bunch of sketches that belong together in some meaningful way (i.e. "blocking notes", "director's comments on blocking", or "guidelines"). For this reason, all the strokes on a layer (not just those made after a particular change) are affected by that layer's colour, opacity, and stroke thickness settings.
By default, most operations occur only on the 'active' layer. The active layer can be identified as the one with the different panel colour (in the default set, an light orangy-brown colour). Clicking on a layer, or changing any of its settings will make it the new active layer.
The active layer can also be identified by looking at the status indicator (in the top right-hand corner of every view with Grease Pencil data being shown).
Grease Pencil can be used to do basic pencil tests (i.e. 2D animation in flipbook style). Sketches are stored on the frame that they were drawn on, as a separate drawing (only on the layer that they exist on). Each drawing is visible until the next drawing for that layer is encountered. The only exception to this is the first drawing for a layer, which will also be visible before the frame it was drawn on.
Therefore, it is simple to make a pencil-test/series of animated sketches:
1. Go to first relevant frame. Draw.
2. Jump to next relevant frame. Draw some more.
3. Keep repeating process, and drawing until satisfied. Voila! Animated sketches.
Onion-skinning (also known as ghosting), is a useful tool for animators, as neighboring frame(s) are lightly drawn by Blender. It allows animators to make judgments about movements, by comparing movement from different frames.
Usage Notes:
It is possible to set a Grease-Pencil block to be loaded up in the Action Editor for editing of the timings of the drawings. This is especially useful for animators blocking out shots, where the ability to re-time blocking poses is one of the main purposes of the whole exercise.
1. In an Action Editor window, change the mode selector (found beside the menus) to 'Grease Pencil' (by default, it should be set to 'Action Editor').
2. At this point, the Action Editor should now display a few 'channels' with some 'keyframes' on them. These 'channels' are the layers, and the 'keyframes' are the frames that each layer has. They can be manipulated like any other data in the Action Editor can be.
All the available Grease-Pencil blocks for the current screen layout will be shown. The Area/Grease-Pencil datablocks are drawn as green channels, and are named with relevant info from the views. They are also labelled with the Area index (which is currently not shown anywhere else though).
It is possible to copy sketches from a layer/layers to other layers in the Action Editor using the Copy/Paste buttons in the header. This works in a similar way as the copy/paste tools for keyframes in the Action Editor.
Sketches can also be copied from one screen (or view) to another using these tools. It is important to keep in mind that keyframes will only be pasted into selected layers, so layers will need to be created for the destination areas too.
In the 3D-view, sketches on the active layer can be converted to geometry, based on the current view settings. Sketches are converted into geometry by transforming the points recorded when drawing (which make up the strokes) into 3D-space (based on the current view settings). Currently, all points will be used, so it may be necessary to simplify or subdivide parts of the created geometry for standard use.
Sketches can currently be converted into one of three types:
