Script Documentation
written by Bohdon Sayre


Setting Up a Smear Mesh
Smear Mesh Settings
Animating a Smear Mesh
General Info
Contact Info


BoSmear is a mel script that allows you to deform your character in a "two-dimensional" way. Using a smear mesh that is dependent on your scenes camera, you can stretch and skew your character on a frame by frame basis to add exaggeration or other techniques. Because of the nature of boSmear, your character can still freely move about the scene, and the camera can also move, without changing the effects of the smear mesh. Furthermore, by using a mesh to drive the deformations, you can take advantage of tools such as soft selection in quickly shaping and warping your character.


Copy the boSmear.mel file to your maya scripts directory.
In most cases, this will be your ~user/MAYA/<version>/scripts folder.
Restart Maya, or run rehash in the script editor.
Run boSmear in the script editor, or drag it to a shelf for later use. That's it!

Setting Up a Smear Mesh

After running boSmear in the script editor or command line, the smear setup window will appear:

• The first thing you'll need to choose is which Camera the smear will be applied to. Because smearing is a camera-based feature, the mesh will always stay with this camera, and it cannot be changed later. This is usually the final camera that will be used for rendering.

• The second option is the Resolution. This is the amount of vertices (W x H) of the smear mesh that will be created. If this resolution is too high, the smear will not be as smooth, and will also be harder to animate. If this is too low, however, you may not have a level of control that is specific enough for both close shots and long shots. The default values usually work best.

• The third option, known as the Target, is simple a control or object that will always follow the character, at at most times be in the center of the character. The main COG controller or hip controller usually works best for this.

• The fourth option is what Geometry will receive the smear deformations. This can be all of the geo of your character individually, or a group containing everything to be deformed. Don't forget to include all aspects of the character, including buttons, eyelashes, and other small pieces of geo.

• Finally, click Create Smear, and you're ready to animate! The Controls window will automatically appear once the smear mesh is built, but next time you'll need to use the Smear Controls button to get it back. Check out the Animating section for tips and tricks.

Smear Mesh Settings

When a smear is created, there are a few attributes/settings that can be accessed by selecting the smear mesh (viewable in the camera chosen during setup).

• The Smear Weight attribute is basically the on off switch for you smear. It can be animated for smooth transitions, and while off, eliminates any speed detriments caused by the lattice deformer on your entire character. It's recommended to turn this to 0 while not animating or requiring the smear.

• The Smear Soften attribute controls how the lattice deforms geometry. The higher this value, the smoother the lattice will be in affecting geometry. Some values (such as odd numbers) can create edgey effects on your geometry which is undesirable. Recommended values are 2 or 4.

• The Smear Depth Scale controls how deep the lattice currently is. If your character exceeds this depth (before smear), some vertices will be left behind and you'll need to increase this value. The smear deformations work best when this is smaller, so feel free to animate this value in order to conform to the changing poses of your character.

• The Smear Depth Guide is simply a visibility switch for a bounding box that represents the Smear Depth Scale. Use it to effectively determine if your character is within the current depth scale.

• The Smear Mesh Transparency simply controls the transparency of the smear mesh in the camera. It can be useful to grasp the smear meshes topology when smearing in Z. It also let's you know if the smear mesh is hidden or visible. Default value is 0.9.

Animating a Smear Mesh

When animating a smear mesh, it's best to use the provided Animation Controls window (fig. 1). You can get this window by clicking on Smear Controls Window in the main window, or by running source boSmear;bsmSmearControlsWin; (you may want to add that to your self).

fig. 1

fig. 2
• The Smear Mesh option menu will determine which smear in the scene you are currently affecting. This is for when there are multiple smears in one scene.

• Toggle Mesh Visibility will show/hide the currently active smear mesh in all views.

• Reset Mesh will return all of a smear meshes vertices back to their default positions of 0 0 0. Vertices have default values of 0 0 0 for a reason, so that they can also be zeroed out manually. You can select a portion of vertices and set their positions to 0 0 0 in the channel box all at once, while leaving other vertices alone (fig. 2). Reset Mesh, however, will always reset all of the vertices of a given smear mesh.

• Key All Mesh Verts will key all of the vertices of the given smear mesh. If the graph editor is open, it will also show the animation curves of all vertices automatically.

• Show Keys in Graph Editor displays the animation curves of all vertices in any open graph editors. It is identical to selecting the shape node of a smear mesh (selecting the mesh and pickwalking down). This action also happens at the end of Key All Mesh Verts.

• It's a mesh!! The smear mesh is a mesh for a reason!, you can use soft selection, sculpt geometry tools like relax, smooth, push, pull, or anything else you use to move around mesh verts. Just don't perform any actions that add history to the smear mesh, as the results could be unpredictable.

• Use it to compliment your existing animation. The smear tool is best used on a few frames here and there for added exaggeration during extreme poses. It's best to key and shape the mesh uniquely on every frame that it is involved in, rather than tween the mesh over several frames. It's usually better to get as much of the poses as you can out of normal animation, and add a layer of smear animation on top of that. There are numerous possibilities though! and the tool can be used in many ways (such as the effect of a warp field as an object moves across screen).

General Info

After setting up a smear, the new node hierarchy is rather simple, but there are a few things you should know.

• When animating the mesh, you will be keying the vertices directly. In order to see the animation curves of all the vertices, you would need to select the shape node of the smear mesh you see in the camera. You can do this easily by selecting the mesh and pick walking down (hotkey: down arrow). If you use the Controls window, however, you won't have to worry about this, as keying the mesh will automatically display the curves in the graph editor (aka: automatically select the shape node).

• The lattice that influences the character is created at a default size, if your character is larger than default, you may notice stray vertices when using the smear mesh. You can easily fix this by changing the Smear Depth Scale. If you think your character may be outside of the lattice, or that the smear isn't behaving as expected, use the Smear Depth Guide to make sure your character is fully within the boundaries (see Settings for details on both attributes).

• Multiple smears on several different objects IS supported. As of now you'll want to hide any other smears that you aren't working on, but this will become automatic in future updates.

• boSmear 2.0 has been tested with Maya 2008.

Contact Info

As you use the boSmear tool, feel free to email me with any questions, comments, tips or requests! I'll be glad to see what I can do.
Bohdon Sayre
bohdon at gmail dot com

Copyright © 2009 by Bohdon Sayre. All rights reserved.