This technique, also know as Shape Animation / Shape Blending, enable you to deform an object from one shape to another. The principle is simple: you have a base shape (the un-deformed state) and a target shape. By determining a percentage, for instance by pulling on a slider, you can by smoothly interpolate between the two shapes: the points of the object will move from the positions they are in for the base shape, to the positions of the corresponding points on the target shape.
For this to work the base object and the target need to have:
- the same amount of points.
- identical topology: the points should be in the same order and connected in the same way on both the base and the target object.
Maya actually accepts objects with different topology, but the resulting morph can be erratic and is probably not very useful
For all you visual learners, here is a video in which I explain the basics of creating blend shapes. The Shape Editor now provides an easier way to create blendShapes.
The blendhape menus have moved since Maya 2016
- To create a blendhape, go to Animation → Anim Deform → [Create] Blend Shape
- To add a blendshape, go to Animation → Anim Deform → [Edit] Blend Shape → Add
Creating a morph: Blend Shape
- Create a polygonal ball, or load an object
- Duplicate the object
By making a copy you are making sure that both the target and base object will have tha same point count and topology
Renamimg the new shape something with “Target1” in it will help you stay organized
- Deform the new target object
You have to move points / vertices – scaling the entire object for instance does not change its shape and will not be reflected in the morph.
It helps to move it to the side of the original so you can more easily see what you are doing.
- Select the new shape (the target) and then shift select the original shape.
- From the animation menu: choose Anim Deform → [Create] Blend Shape
- Among the tabs of the attribute editor for the base shape. you will find one called blendShape1, representing the blandshape modifier node. Under Weight you can determine the influence of the target shape, with the slider Deformer Attributes → Envelope you can activate the deformer. Both have to be non zero to see any effect
Adding more Blend Shapes / Targets to a Deformer
This works basically the same as adding the first blend shape:
- Duplicate the base object
- Deform the new target object
- Select the new shape (the new target) and then shift select the original shape.
- From the animation menu: choose Anim Deform → [Edit] Blend Shape → Add
- In the attribute editor of the base shape, under blendShape1 → Weight you now have two sliders which you can use to dial in the cntribution of each blend shape
Hiding the Target Shapes
Once satisfied with the blend shapes, you can hde them (select the object and hit CTRL-h (Display → Hide → Hide Selection). You can also select all the blend shapes and create a separate display layer with all of them in it so you can easily toggle them on and off. If you are really sure you have them nailed down and want to free up memory, you can even delete the copied objects, the base object actually contains extra copied of all youe shapes so the morphs will still work. You can just no longer edit them.