Computer Animation Ying Zhu Georgia State University Deformation

Deformation techniques Modifiers SimpleDeform Cast Curve Lattice Shape keys Relative shape keys Absolute shape keys

SimpleDeform Modifier Apply simple deformations to the target object Twist Stretch Bend Taper Change the Factor to adjust the scale of deformation

Cast modifier Cast an object to the shape of Cuboid, Sphere, Cylinder

Curve modifier Add a curve to the scene, give it a name Add a modifier to the target object (e.g. a piece of paper, etc.) Type in the name of the curve Now you can manipulate the curve to deform the target object Subdivide the target object to get more realistic deformations Good for animating papers, cloth, eye brows, etc.

Lattice modifier Use lattice to deform the space occupied by the lattice and everything in that space. Press Space bar and add a lattice Give it a meaningful name You may want to scale it Under Editing (F9) panel, Lattice tab Change the values of U, V, W to adjust the resolution of the lattice If you wan to deform the object now, surround the target object with the lattice.

Lattice modifier Select your target object, add a Lattice modifier Type in the name of the lattice in the “Ob” field Select lattice, enter Edit mode Now manipulate the vertices on the lattice to deform the target object Changing the overall size of the lattice doesn’t change the size of the object It’s deformation of lattice that deform the object.

Lattice modifier You may place the lattice away from the target object, and then move the target object to pass through the lattice. The object will be deformed in the region where the lattice is deformed In the above process, you may create key frames for the target object so that it’s deformed in the middle of the animation

Lattice parenting Besides lattice modifier, there is another (old fashioned) method to attach a lattice to a target object Select a target object and then select a lattice Press ctrl + P, choose “Lattice Deform”

Relative shape keys Relative shape keys are commonly used for animating facial expressions Shape key is like key frames for deformation You define a basis shape key for an object and subsequent shape keys Each subsequent shape key is based off of the basis shape key Usually not a good idea to delete vertices in shape keys

Relative shape keys Relative shape keys provide a lot of flexibility You can mix different shape keys You can adjust the influence value for any shape key to create a shape that’s somewhere between the basis shape key and this shape key

How to add relative shape keys? There are several ways to add shape keys. But I found the following method to be the most robust. Select a target object, enter Edit mode Under Editing (F9) panel, select “Shapes” tab It’s next to the “Modifiers” Press “Add Shape Key” button The first time you press this button, the basis shape key is created. By default the “Relative” button is pressed

How to add relative shape keys? Press “Add Shape Key” button to add another shape key By default it’s named “Key 1”, “Key 2”, etc. You may want to give them meaningful names (e.g. smile, sad, open, etc.) Deform the target object in Edit mode When you are done, press Tab key to leave Edit mode, and then press Tab again to enter Edit mode The shape key is saved at the moment you leave the Edit mode

How to add relative shape keys? Repeat the above process to add more shape keys Sometimes you may want to enter Object mode, go back to the basis shape key, and then enter Edit mode to create another shape key based on the basis shape key

Shape keys for lattice The above process works for both meshes and lattices. This means you can create shape keys for lattice deformations You can select a lattice, enter Edit mode, add a shape key, deform the lattice (which in turn deforms its associated object), leave Edit mode, then enter Edit mode, add more shape keys, and so on.

Shape keys for curve You can add shape keys for curves Select curve, enter Edit mode, deform the curve Press I to bring up the Insert Key menu Select curve Leave Edit mode and then re-enter edit mode Repeat the above process to add more shape keys for the curve

How to add relative shape keys? In the Object mode, select the target object, you can review the shape keys by pressing the left and right arrow buttons in the “Shapes” tab (in Editing panel)

How to animate with shape keys? There are several ways to insert shape keys to an animation Insert shape keys into the Shape IPO curve Insert shape keys in Action Editor (ShapeKey Editor)

Editing shape IPO curve Select the object that you have defined shape keys for, open IPO Curve Editor window In “Ipo Type”, select Shape Blender has separate IPO curves for shape keys You’ll see all the shape keys in this window Select any shape key to view and edit its curve If a curve doesn’t exist, enter Edit mode, press ctrl + LMB to add new point and a new curve

Editing shape IPO curve The vertical axis represent “influence” Allowed values are between 0.0 to 1.0 Each point on the curve means how much of that shape key will affect (deform) the mesh at any given frame. If there are multiple shape curves at one frame, it means the final shape of the object is a combination (blend) of several shape keys.

Mixing relative shape keys in ShapeKey Editor Select the object that you have defined relative shape keys for, open Action Editor window In Editor Mode menu, select ShapeKey Editor You need to have a Shape IPO curve for each shape key to see shape key slider bars in the action editor These are the sliders for changing influence of each shape key

Mixing relative shape keys in ShapeKey Editor To add a relative shape key for a particular frame, move the green vertical line to that frame, and then move the slider bar for that shape key. The moment you touch the slider bar, a marker will be added for that frame You can delete and move the markers You can insert relative shape keys along horizontal lines (shape change over time) You can also insert relative shape key along vertical lines (mixing shapes for one frame)

Mixing relative shape keys in ShapeKey Editor Along the horizontal (time) line, you need to decide when you want a shape key to appear, when you want it to reach full deformation (influence = 1.0), and when the shape goes back the basis shape For example, you add a “smile” shape key with influence = 0.0 at frame #20 Then add the “smile” shape key with influence = 1.0 at frame #80 Then add the “smile” shape key with influence = 0.0 at from #200

Mixing relative shape keys in ShapeKey Editor This means you will start to see the “smile” at frame #21 Gradually the “smile” will reach its full deformation at frame #80, and then gradually goes back to the basis shape at frame #200 Blender will automatically interpolate between the same shape key inserted at different frames Relative shape keys are interpolated along horizontal lines

Mixing relative shape keys in ShapeKey Editor Along vertical lines, you can insert multiple shape keys for one frame. Blender will combine (blend) them. For example, you have both “shape key 1” (influence 0.3) and “shape key 2” (influence 0.7) for frame #20. This means at frame #20, the shape of target object is a combination of 30% “shape key 1” plus 70% “shape key 2”. Relative shape keys are blended along vertical lines

Adjusting shape IPO curve After mixing relative shape keys in ShapeKey Editor, you can switch to IPO curve editor to adjust the Shape IPO curve Adjust how fast or slow a shape key reaches its full deformation or disappears

Mixing relative shape keys in ShapeKey Editor The ability to mix multiple shape keys is very useful It makes it possible to create complex animation by combining a few simple shape keys Particularly useful for animating (mixing) facial expressions For example, mouse open 70% plus left eye open 50%

Absolute shape keys Difference between a absolute shape key and a relative shape key There is no “influence” value for an Absolute Shape Key You cannot apply 70% of an Absolute Shape Key You cannot mix absolute shape keys in the ShapeKey Editor Otherwise they are similar