The Layers window.
A Moho document is composed of layers, each of which can be independently edited and animated. Layers can be thought of as transparent sheets of plastic. You can draw separately on each of these sheets, and the final picture is the composition of all the sheets stacked on top of one another.
Layers can be added, removed, copied, and re-ordered. The Layers window is where all these operations take place in Moho, and is the topic of this section.
The Layers window has two sections of interest. As seen below, these consist of the toolbar and the layer list.
The Layers window.
Most of the Layers window is taken up with the layer list. This is a vertical scrolling list of all the layers in the document. The layers are stacked in order from bottom to top. That is, when the project is displayed, the lowest layer in the list is drawn first, followed by the second from the bottom, and so on up to the top. When two layers contain objects that overlap, this ordering determines which object is in front and which is behind.
Each layer is represented in the list with an entry that looks something like this:
A single layer in Moho.
Only one layer can be edited at a time in the Moho working area. The layer currently selected for editing (the active layer) is displayed in a highlighted color. To select a different active layer, just click on its entry in the layer list. A layer's entry provides you with three pieces of information: what type of layer it is, its name, and whether the layer is visible.
At the left side of a layer's entry in the list is a visibility control, which controls whether a layer is visible or not. If a pair of eyes is visible in this box, any objects drawn in the layer will appear in the main Moho window, as well as in any rendering of the project. If you click this box, the layer will turn invisible and will not appear in the main Moho window. This can be a convenient way to remove clutter in the main window when you don't need to see all the layers at once. Also, only visible layers will appear when you render a view of the project or export an animation - you can generate test movies much quicker if you turn some layers invisible that don't involve what you're currently working on. Note: the visibility box of the currently active layer behaves differently. The currently active layer is always visible (how could you edit it if it wasn't?), and clicking its visibility box (while holding the <alt> key) will turn all the other layers at the same level visible or invisible.
To the right of the visibility control is an icon that indicates what type of layer each entry in the layer list is. The different types of layers include vector, image, group, bone, switch, particle, 3D, and note layers.
Certain types of layers act as "groups", and can contain other layers within them. (You can think of them like folders on your hard drive.) These layers have a triangle on their left side. Clicking this triangle opens and closes these group layers, allowing you to access or hide the sub-layers they contain.
Layers can be re-ordered simply by dragging one layer above or below another layer. Just click and drag the layer you want to move - you will see a red insertion bar indicate where the layer will be placed when you drop it. When the insertion bar appears at the location you choose, just drop the layer and you're done. You can also use this method to drag sub-layers into or out of group layers. Layers can be re-ordered at any time, although their order is not dynamic over time. That is, the layer ordering cannot change in the middle of an animation, for example to make one object appear to move in front of another object.
The last thing you can control in the layer list is the property set of any layer. By double-clicking a layer in the list, a dialog will appear with various options controlling the appearance and behavior of the layer. This dialog is described in the Layer Settings section below.
At the top of the Layer panel is a toolbar that provides several layer operations. The buttons in the toolbar are described below:
New Layer 
Adds a new, empty layer to the project. A popup menu allows you to choose the type of layer you want to add. The new layer is placed directly above the current active layer.
Duplicate Layer 
Makes a copy of the current active layer and adds it to the project. This new copy is placed directly above the current active layer. If you duplicate a group layer, all of the sub-layers inside it will be duplicated also.
Delete Layer 
Deletes the current active layer. This operation cannot be undone, so you will be asked to verify if this is really what you want to do.
Layers Settings 
This command brings up a dialog with various controls to modify the layer's appearance and behavior. The next section, Layer Settings, goes into detail about these options. The Layer Settings dialog can also be invoked by double-clicking the current active layer in the layer list.
The Layer Settings dialog can be invoked either by double-clicking a layer in the layer list, or by selecting a layer, then clicking the Layer Settings button in the layer toolbar. The various controls are grouped into tabs that we'll describe in order.
Layer Settings.
This tab is available for all layer types, and controls general layer properties.
Name
This field allows you to change the name of the layer. You can type in any name for the layer you want here, and the name will appear in the layer list after you click the OK button. Good names make working with large projects much easier. Examples of layer names might be "Background", "Body", or "Head".
Hide in editing view
Turn on this checkbox to hide the layer while editing. The layer will still appear in rendered output, but will be invisible in Moho's edit view. This can be useful to reduce clutter and improve performance. Things you might consider hiding in the editing view are background details, texture and detail layers, or special effects like particle layers. Note that if a hidden layer is the currently active layer, it will temporarily un-hide itself so that you can edit whatever it contains.
Don't render this layer
If this box is turned on, then the layer will not appear in any rendered/exported movies. This option is usually used for some kind of "helper" layer. For example, you might draw a layer with some guide lines to help you draw and animate a scene, but you don't want those guides to appear in the final output. Note layers have this option turned on by default.
Compositing Effects
This group of controls allow you to change certain layer properties over time. When you modify any of these at a frame greater than 0, you will add a keyframe to the corresponding layer effects channel. For example, if you go to frame 1 and un-check "Visible", then go to frame 20 and re-check Visible, that layer will not appear in the final animation until frame 20.
So, that explains the first checkbox - it controls whether a layer is visible in the final output. It is important to note that this checkbox is totally independent of the visibility box displayed in the layer list: these are two separate notions of visibility, and don't affect each other at all. The visibility control in the layer list is meant for your editing convenience: you can turn one layer off while you work on another. The visibility checkbox in this dialog is meant to allow certain effects during an animation. For example, if you had a layer with a drawing of a glowing lightbulb, you could un-check the visibility of this layer at frame 1, then turn it on at frame 10, off at frame 20, on at frame 30, etc. to create the effect of a blinking light.
The "Blur radius" field lets you apply a blur (in pixels) to an entire layer to simulate such effects as camera focus. The blur can be animated over time to make a layer look like its coming in and out of focus.
The "Opacity" field allows you to modify the transparency of an entire layer. An opacity value of 100 will not affect the layer at all, while a value of 0 will make it totally transparent. By changing the value from 0 at frame 1 to 100 at frame 10, the layer will seem to gradually appear out of nowhere, which in some cases is more desirable than the type of on/off visibility provided by the "Visible" checkbox.
Finally, there are two checkboxes: "Flip horizontally" and "Flip vertically". Clicking these boxes flips the entire layer in the direction specified. (If the layer is a group layer, then the sub-layers inside it get flipped as well.) This can be convenient in the case where you want to duplicate a layer and have the second copy face the first one as a mirror image.
Rotate to follow path
When this checkbox is turned on, the layer will automatically rotate to follow its direction of movement. (Specifically, the "up" direction will turn to follow the direction of layer translation.) This can be useful for creating things like flowing arrows that need to point in their direction of movement.
Rotate to face camera
When this checkbox is turned on, the layer will automatically rotate around its vertical axis so that it always faces the camera. This can be useful when using Moho's 3D camera - especially for scenery-type objects. Trees, for example, that always face the camera can save you a lot of work.
Use HSV modifier image
This checkbox lets you use an image file to distort the colors of the layer. Sometimes you may want to do this to break up the solid colors in your project and make it look less computerized. The exact behavior of this feature is difficult to explain. The best way to try it out is to use one of the HSV modifier images included with Moho. These images should be pretty close to 50% gray. Other images may produce bizarre, unexpected results. Feel free to experiment - you can always turn off this checkbox if you don't like the results.
Scale compensation
When this box is checked (as it is by default), and you scale an entire layer larger or smaller, the lines in the final rendered output will automatically get thicker or thinner so that they retain their relative weight in the overall image. Also, layer effects like blurs and shadows will become larger or smaller to match the scale of the layer.
Immune to camera movements
Sometimes you may want to make some layers ignore camera movements. For example, certain backgrounds or title or logo layers you may want to stay in one place on the screen even while you move the camera around.
Immune to depth of field
The depth of field function (in the Project Settings dialog) lets you simulate the blurring of objects with different distances from the camera. This option allows you to turn off this effect for any particular layer.
Layer blending mode
Normally, layers are composited on top of each other simply according to the transparency of each layer. The layer blending mode popup lets you select a different blending mode for each layer. This can be very useful for simulating shading and lighting effects.
The controls in this tab allow you to apply automatic shadows and shading to an entire layer.
Layer Shadow
This section lets you apply a drop-shadow effect to a layer. Checking the "Shadow on" checkbox will make all objects in the layer cast shadows on the layers underneath.
"Shadow direction" controls the direction the shadow is cast. Just drag the knob in circles to change the direction of the shadow.
"Offset" controls how far the shadow appears from the actual objects. A larger offset makes objects appear higher up above the layers below them. "Blur" determines how hard or soft the edges of the shadow appear.
The "Expansion" control allows you to expand the reach of the shadow. This can be useful for halo-type effects. Try an Offset of 0, Blur of 8, and Expansion of 8.
Finally, clicking on the "Shadow color" color swatch lets you change the color of the shadow that is being cast. You can also modify the transparency of the shadow with this control.
Layer Shading
This section is similar to the "Layer Shadow" section above. However, instead of producing a shadow effect behind the layer, these controls let you apply a shading effect on top of the layer. Checking the "Shading on" checkbox will make all objects in the layer appear shaded, giving them a rounded edges effect.
"Shading direction" controls the direction the shading appears. Just drag the knob in circles to change the direction of the shading.
"Offset" controls how far inside the layer the shading appears. A larger offset makes objects appear to have more "rounded" edges. "Blur" determines how hard or soft the edges of the shading appear. The "Contraction" control allows you to pull the shading further into the center of the layer.
Finally, clicking on the "Shading color" color swatch lets you change the color of the shading that is applied. You can also modify the transparency of the shading with this control.
The controls in this tab control the motion blur effect for this layer. Motion blur can be turned on and off during the course of an animation. Checking "Motion blur on" turns on the effect. The default settings work pretty well for a basic motion blur effect.
"Frame count" controls how many copies of the layer should trail behind itself. The higher this number, the longer it will take to render your animation. Sometimes a high number may be used for an exaggerated cartoon effect.
"Frame skip" controls the separation between blur frames. A larger number will cause the blur effect to trail farther out behind the current position.
"Start opacity" and "End opacity" control how the blur fades away behind the layer. Generally, a motion blur effect will fade a bit as it trails behind the layer. For some special effects, however, you may not want the motion blur to fade at all. In those cases, set both values to 100 to keep the motion blur completely opaque.
"Blur radius" controls the radius (in pixels) of the motion blur effect.
This tab is used to control layer masking. Layer masking controls the visible region of a layer - objects in a layer that are not within the visible region of the mask will not appear in the final output.
If the layer is a group or bone layer, then the following additional options are available: "No masking in this group" means that no masking will occur in this group. "Mask on - reveal all" means that masking is on, and by default all sub-layers will be fully visible. "Mask on - hide all" means that masking is on, and by default all sub-layers will be invisible (this is the most common option when using layer masking).
All other layers inside a group will have the following options for layer masking:
The masking controls are simple but powerful options that can be used for all kinds of creative tricks. The best way to explain these is with a hands-on example that you can try out in the Tutorials section.
This tab is only available for vector layers, and controls the appearance of lines and fills in the layer. The controls here enable the vector "noise effect". By adding "noise" to a layer, you can make it look more hand-drawn, or at least get rid of some of that pesky computer precision. Of course, that's up to artistic interpretation: if you like computer precision, the noise effect may not be the feature for you.
The first two checkboxes turn on noise for outlines and/or fills. If you turn on both of these, all the shapes in the layer will become distorted. However, if you check only one, the effect will look like someone was coloring but didn't stay in the lines. The circle displayed on the right side shows a preview of what your noise effect settings will do to the final drawing. (The best way to understand this feature is to just start clicking the checkboxes and watch the circle.)
The third checkbox, "Animated noise", controls whether the noise factor will vary over time in your animation. This can lead to either a very distracting look, or a very sketchy, free-form one, depending on your tastes. Again, experiment with this and watch the circle.
Finally, there are three input boxes: "Offset", "Scale", and "Extra lines". Offset determines how far in pixels (on average) your drawing will be distorted from its original shape. Scale determines the "jaggedness" of the distortion. Larger scale numbers will result in smoother, lumpier distortion, while smaller numbers will give you a more scribbled look. Extra lines tells Moho to draw a number of extra copies of each line, distorting each in a different way.
This tab is only available for group and bone layers. Depth Sort has two controls that can be used with Moho's 3D features. The "Sort layers by depth" checkbox allows sub-layers to move in front of and behind each other during an animation. Normally, layers are drawn in the order they appear in the Layers panel. However, with this option turned on, layers are displayed according to how far they are from the camera. See the Tutorials section for an example of using this feature. Typically, layers are sorted by their depth from the camera, but if you're trying to create a 3D object using multiple Moho layers (like a cube or pyramid), you may want to turn on "Sort by true distance". This tells Moho to sort layers by the distance from the camera to the layers' origins, rather than by depth. Usually this option will be left un-checked.
This tab is only available for image layers. There are only three controls in this tab. First, a button labeled "Source Image..." lets you select the image to be used in the image layer. Use this if you want to change the image, or if it got lost for some reason. Next is a checkbox labeled "AVI movie has alpha" - turn this on if the image layer is using an AVI movie, and that movie includes an alpha channel. Finally, there is a checkbox labeled "Warp using bones". If this box is checked and the image layer is placed inside a bone layer, the bones can be used to warp the image as if it were printed on a rubber sheet.
This tab is only available for switch layers.
The first control in this tab is a button labeled "Source Data..." that lets you select a data file used to control the switch layer. A data file is not required (you can control a Switch layer manually by right-clicking its entry in the Layers window), but if you do want to use a data file you have two choices:
1) You can create a switch data file for lip-syncing using a program like Magpie or Pamela.
2) If you want a quicker lip-sync solution, you can use an audio file as a data file. (QuickTime is required for this function.) In this case, your switch file should contain several version of a mouth shape, ranging from closed to wide open. The volume of the audio file will control which mouth shape is used at which frame. If you do use an audio file to control the Switch layer, you can either use automatic volume gain (recommended) or set the gain manually. The gain controls how wide the mouth gets. When using manual gain, start with a value of 1 - if the mouth seems too wide, try smaller values (0.75 or 0.5). If the mouth isn't wide enough, try higher gain values (1.5 or 2). See the Tutorials section for an example of using this function.
The other control is a checkbox labeled "Interpolate sub-layers". If this box is checked Moho will do smooth transitions between the sub-layers as long as they're all vector layers and contain the same number of points.
This tab is only available for particle layers. The description for how these controls affect a particle layer can be found in the Particle Layer section.
This tab is only available for 3D layers. The "Default color" and "Edge color" boxes let you adjust the color of the 3D model. If you imported a 3D model that includes colors and textures, then those will be used instead. The default color is only used when no color is defined by the model itself.
The "Polygon orientation" controls let you adjust whether the polygons in your model are oriented clockwise or counter-clockwise. After importing a model, if it looks turned inside-out or otherwise distorted, try switching the polygon orientation.
The "Edge offset" value lets you fine-tune how much offset is used to draw the cartoon edges around your 3D model. A value of zero corresponds to no cartoon edge at all.
Finally, there is a checkbox labeled "Warp using bones". If this box is checked and the 3D layer is placed inside a bone layer, the bones can be used to warp the 3D model. Be aware that although the model is three-dimensional, bone layers are only two-dimensional, so you will be limited in the ways you can control the 3D object using bones.
This tab is only available for note layers, and lets you change the text label in the note.