CS 285: SOLID MODELING

Lecture #12 -- We, Mar. 6, 2002.

Preparation

Background and Motivation

• Context: Assignment #8.
• How would YOU get the B-rep from a CSG object description ?
• Implementing clean 3D Boolean operations is difficult !

Paper Presentation and Discussion

1. What does CDA stand for ?
2. What is a CDA ?
3. Why does it help render the result of Boolean Operations ?
4. How do you convert an arbitrary CSG scene into the CDA form ?
5. What kind of objects would this method have trouble with ?
6. On what scenes does this method shine ?

Review of Results of CAD Design of Snap-together Tiles

• Look at your designs closely in SLIDE with backface culling enabled!

• Try to make your designs clean B-reps, i.e. no "unmatched edges."
  To test for that property, save your file as SIF and see how many red (unmatched) edges that you get.
  To be merged, edges must also match in length; thus, if you split one edge, you should also split its sibling at the same positions.
• Is bubble attached securely to tile -- check roads !
• How to make two identical tiles in parallel: Use "edit curves", replicate.

Homework Assignments:

A#7: Snap-together Tiles
Phase 3: Build four Prototype Tiles

Reading Assignment: "Layered Manufacturing of Thin-Walled Parts"