February 19, 2011

Learn to animate flocking behavior in this hour-long series of seven free videos. To create a group of butterflies, we cover modeling, animation, and dynamics. The key element is the Particle Instancer, which places models on top of particles.

This is an intermediate level exercise, building on the previous Magic Wand tutorial. Some of the learning outcomes of this tutorial include:

Model and animate a simple articulated insect such as a butterfly
Convert the animation to a model sequence using Animation Snapshot
Prepare the Snapshot hierarchy for use with the Particle Instancer
Sketch particles with the Particle Tool
Instance geometry to particles with the Particle Instancer
Write a Creation Expression to drive a custom attribute
Employ Radial Fields to attract and repel particles from one another
Fine-tune Field attributes such as Max Distance and Attenuation

Supplemental material

Lesson Notes

Lesson Notes complement tutorials. They reduce complex multi-stage procedures to short bullet points. Brief explanations reinforce key concepts. The outline format helps learners focus on the content, rather than spend a lot of time reading. To access Lesson Notes, you need to join the guild.

Here is a sample of the Lesson Notes:

1. Modeling
   1. Establish a scale convention
      1. For a small insect such as a butterfly, 1:1 scale makes sense
      2. By default, one standard Grid line is one centimeter
   2. The model must face in the world’s positive X axis
      1. The usual convention for character/creature modeling is that the model should face in the world’s positive Z axis
      2. This time we must do it differently, because the Particle Instancer has this special requirement
2. Create the insect body
   1. Build in Top view, Snap to Grid
   2. Create > CV CurveTool
      1. Options:Curve degree = 3 Cubic
      2. Click twice to create sharp corners
         1. Wait a heartbeat between mouse clicks, don’t double-click
      3. Don’t close the curve
   3. First and last control vertices must have a Z position of zero
      1. If you haven’t snapped to the grid, then you can move the CVs manually
      2. Method one
         1. Select the end CVs
         2. Click-hold and drag a selection rectangle around the endpoints to select multiple points at the same location... don’t just click once
         3. Channel Box > CVs (click to show)
      3. Method two
         1. Select the end CVs and choose the Move tool
         2. Input Line at the top right of the Status Line (top toolbar)
         3. Click the down arrow and choose Absolute Transform mode, if necessary
         4. Set Z value to zero
   4. Object mode: Surfaces > Surfaces > Revolve > Options
      1. Axis Preset: X
      2. Output Geometry: Polygons
      3. Type: Quads
      4. Tessellation Method: General
   5. Attribute Editor: nurbsTessellate node > General Tessellation Options

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