Introduction to Computer Aided Modeling

Instructor: Brent Rossen

CGS 3220Lecture 8Sculpting,

Blend Shapes,

andDriven Keys

Overview

Freezing TransformationsSculpting SurfacesCreating Blend ShapesAdding Custom AttributesUsing LocatorsSetting Driven Keys

Sculpting Geometry

Sculpting is a part of Maya’s Artisan ToolsFirst we’ll try it with a sphere, then we’ll use it to beat up our OrbCreate > Primitive Polygons > Sphere options

Set Subdivisions Axis and Subdivisions Height to 60Apply a phong to it so we can see it better

Keep the sphere selected, Edit Polygons > Sculpt Polygons Tool > Options

Polygons Tool Options

Hitting the options box when we open it opens the tool settingsCurrently, the most important items are Radius and Max Displacement

Radius: .2Max Displacement: .1

Now try painting on the surface, alternate between push, pull, and smooth and make some image

Setting up the Orb

We’ll now use the sculpt too to beat up the orbGroup the orb geometry ctrl+g, rename it orbGroupSelect the whole hierarchy of orbGroupModify > Freeze TransformationsEdit > Delete By Type > History, to start with a clean slate

Sculpt the Orb

Edit > Duplicate options, reset, and make a duplicate copy of the orbGroupMove the new orb next to the original, name it orbCrashGroupWith the orbCrashGroup selected Edit Polygons > Sculpt Polygons Tool optionsReset, Radius: .2, Max Displacement: .1, pullThis time, change the Reference Vector to Y-axis

Beat up the Orb

Now just use the sculpt geometry tool to beat up the orb

Blend Shape Deformer

In the next lesson, we’ll animate the orb colliding with the ground. So we need some way to make the orb transform from our shiny new one, to the beat up one. For that, we use blend shapes.Blend shapes are also used to transform a characters mouth from one viseme to the next

Create the Blend Shape Deformer

Select orbCrashGroup shift-select orbGroupBe sure to select the original last, that way Maya knows which one is getting the deformer applied to itDeform > Create Blend Shape > Options Box

Be sure Origin is set to LocalName it crashBlendShape

Select some part of the orb, go to the channel box or attribute editor, there should now be a crashBlendShape node

Using the Blend Shape

Select the orbCrashGroup on the blend shape node and virtual slider (MMB+Drag) change it from 0 to 1, you should see an effectWindow > Animation Editors > Blend Shape… will allow you to change multiple blend shapes at once, if they are appliedYou can still make changes to the orbCrashGroup, and those changes will propagate to the blend shape and orbGroup

Animation Setup

Now let’s reorganize our hierarchy before we start animatingCreate > Locator, locators do not renderRename the locator to pathLocatorCreate another locator and rename it animLocatorSelect animLocator, shift-select pathLocator and hit p to parent themParent the orbGroup to the animLocator

Add a Custom Attribute

Since the blend shape attribute is hidden in the input nodes, we want to make it easy to get to by including it as an attribute on the animLocatorSelect animLocator Modify > Add Attribute

Enter crashShape as the name Make sure Keyable is checkedData Type should be floatMinimum: 0, Maximum: 1

Press Ok

Connect the Attribute

That attribute doesn’t do anything yet, we have to connect it to the blend shapeWindow > General Editors > Connection EditorSelect animLocator click Reload LeftClick on the Crash Shape attributeSelect any geometry of the orbGroup and highlight crashBlendShapeClick Reload Right, Select Weight > orbCrashGroup

Set Driven Keys

The idea behind a driven key is that one attribute drives the attribute of another

An example of this is if you connected the bulge of a bicep to the rotation of an elbow

What we’ll use it for is to create an attribute on the animLocator to drive the zoom of both the lens and lens tubeModify > Add Attribute

Name: lensControl, Min 0, Max 1, default 0

Define the Driven Keys

Animate > Set Driven Key > Set > OptionsSelect the animLocator click Load DriverSelect lensControl to specify it as the driverSelect the lens and tube of the orb, click Load DrivenHighlight the tube and lens, select the Translate Z and Rotate Z attributes to specify them as driven

Set the Driven Keys

lensControl: 0, translateZ: 0, rotateZ:0, press KeylensControl: 1, translateZ: -.15, rotateZ: 45, press KeyNow, when you move the lensControlattribute from 0 to 1, the translateZ and rotateZ of both the tube and lens will go from 0 to -.15 and from 0 to 45

Wrapping Up

We went over:The Blend Shape Deformer, something you will become very familiar with in later projects as wellThe Artisan Sculpting Tool, a very intuitive way to alter objectsSet Driven Keys, which are essential for animation setup and can save a huge amount of time

Next Time we’ll use the animation locators to animate the orb flying into our garage