2009
Table Of Contents
- Contents
- Overview
- Maya Basics
- Polygonal Modeling
- Introduction
- Preparing for the lesson
- Lesson 1: Modeling a polygonal mesh
- Introduction
- Setting modeling preferences
- Using 2D reference images
- Creating a polygon primitive
- Modeling in shaded mode
- Model symmetry
- Selecting components by painting
- Selecting edge loops
- Editing components in the orthographic views
- Editing components in the perspective view
- Drawing a polygon
- Extruding polygon components
- Bridging between edges
- Adding polygons to a mesh
- Splitting polygon faces
- Terminating edge loops
- Deleting construction history
- Mirror copying a mesh
- Working with a smoothed mesh
- Creasing and hardening edges on a mesh
- Beyond the lesson
- NURBS Modeling
- Subdivision Surfaces
- Animation
- Introduction
- Preparing for the lessons
- Lesson 1: Keyframes and the Graph Editor
- Lesson 2: Set Driven Key
- Lesson 3: Path animation
- Lesson 4: Nonlinear animation with Trax
- Introduction
- Open the first scene for the lesson
- Creating clips with Trax
- Changing the position of clips with Trax
- Editing the animation of clips
- Reusing clips within Trax
- Soloing and muting tracks
- Scaling clips within Trax
- Open the second scene for the lesson
- Creating clips from motion capture data
- Extending the length of motion capture data
- Redirecting the motion within a clip
- Beyond the lesson
- Lesson 5: Inverse kinematics
- Introduction
- Open the scene for the lesson
- Understanding hierarchies
- Viewing hierarchies using the Hypergraph
- Creating a skeleton hierarchy
- Parenting a model into a skeleton hierarchy
- Applying IK to a skeleton hierarchy
- Creating a control object for an IK system
- Constraining an IK system
- Limiting the range of motion of an IK system
- Simplifying the display of a hierarchy
- Applying parent constraints on an IK system
- Planning an animation for an IK system
- Animating an IK system
- Beyond the lesson
- Character Setup
- Polygon Texturing
- Rendering
- Introduction
- Preparing for the lessons
- Lesson 1: Rendering a scene
- Introduction
- Open the scene for the lesson
- Creating shading materials for objects
- Refining shading materials for objects
- Maya renderers
- Rendering a single frame using IPR
- Rendering using the Maya software renderer
- Batch rendering a sequence of animation frames
- Viewing a sequence of rendered frames
- Beyond the lesson
- Lesson 2: Shading surfaces
- Lesson 3: Lights, shadows, and cameras
- Lesson 4: Global Illumination
- Lesson 5: Caustics
- Dynamics
- Painting
- Introduction
- Preparing for the lessons
- Lesson 1: Painting in 2D using Paint Effects
- Lesson 2: Painting in 3D using Paint Effects
- Introduction
- Preparing for the lessons
- Brushes and strokes
- Rendering Paint Effects strokes
- Paint Effects on 3D objects
- Creating a surface to paint on
- Painting on objects
- Using turbulence with brush stroke tubes
- Using additional preset brushes
- Mesh brushes
- Converting mesh strokes to polygons
- Modifying a converted polygonal mesh
- Beyond the lesson
- Lesson 3: Painting textures on surfaces
- Expressions
- Scripting in Maya
- Index
8 Turn on Add Per Particle Attribute, then click the Add Attribute button.
This adds an rgbPP attribute to the particle shape node for Bubbles.
Because you’re adding this attribute as a per particle attribute, you can
give each particle a different color.
Using creation expressions to set a constant color
To set an attribute that doesn’t change during the animation (the particle
color), you’ll use a creation expression. A creation expression executes when
you go to the start time. It doesn’t execute while the animation plays. (For
emitted particles, a creation expression executes for a particular particle when
it is emitted.)
To create a creation expression
1 In the Per Particle (Array) Attributes section of the Attribute Editor,
right-click the rgbPP box and select Creation Expression from the pop-up
menu. Note that the shape node of Bubbles (BubblesShape) is displayed
in the Expression Editor.
When you use an expression to control particle attributes, make sure the
selected object in the Expression Editor is a particle shape node, not the
transform node of the particle object. If a particle object’s transform node
is selected, move the mouse pointer to the scene view and press the down
arrow key to select the particle shape node.
2 Enter this expression and then click the Create button:
BubblesShape.rgbPP = <<1,0,0>>;
When you click the Create button in the Expression Editor, Maya checks
the syntax of the expression. Assuming you made no typing errors, the
expression executes once for each of the 100 particles.
The expression colors all particles in the object red. The double angle
brackets << and >> enclose a vector that sets the red, green, and blue
components of the rgbPP attribute to 1, 0, and 0. In the RGB color scheme,
this gives the object a red color.
If the particles are uncolored, check that you’ve turned on Shading >
Smooth Shade All. This shading mode is necessary for particles to show
the color assigned in an expression.
3 Play the animation. The particles remain red.
586 | Chapter 12 Expressions