CS 285: SOLID MODELING
Lecture #4 -- Thu, Sep. 6, 2007.
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Warm-up Thinking Exercise:
How do you build such a bronze sculpture at the 6-foot scale ?

Discussion of First Homework Assignment:
Procedural, Parameterized Modeling with SLIDE
Introduction to
SLIDE
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SLIDE originated as a toy rendering system for CS 184
- SLIDE lies between Mathematica / Matlab and traditional CAD tools (Solidworks, Autocad)
- It describes boundary representations (B-reps)
- Most numerical values can be substituted by expressions that are evaluated in each rendered frame.
- Offers interactive fine tuning of critical parameters via sliders
- It builds on OpenGl (for rendering) and Tcl (user interface, expression parsing)
- Main drawbacks:
- Not a properly maintained system.
- Tcl is a pain during the debugging process!
The best way to learnSLIDE is by looking at examples, and by modifying those examples.
You should always have the SLIDE Language Specification Page open when you write SLIDE code.
Some SLIDE and Tcl Basics
Look in: http://www.cs.berkeley.edu/~sequin/CS285/CODE/
To get familiar with SLIDE, play with:
Cube.slf
BorLoopTex.slf
KG3Q60paramOptim.slf
To see what can be done with Tcl, look at:
Instancing.slf
Gear.slf
GearMovie.slf
BevelGearMovie.slf
Advice: Do not write Tcl code from scratch! Take a working file and make small changes between test runs.Escape hatch: Later in the course you may use whatever software modeling environment you are comfortable with.
Assignment A#1b: Install SLIDE on your own computer.
General instructions how to do this can be found here: http://www.cs.berkeley.edu/~ug/slide/viewer/slide2004/README
Macintosh users should download: http://www.cs.berkeley.edu/~ug/slide/viewer/slide2004/old_slide2004.tar.gz
More information for the Windows system are here: http://www.cs.berkeley.edu/~ug/slide/pipeline/assignments/instructions.shtml
(see comments on "Installation")
Generalized Sweeps (basic concepts)
The Frenet frame:
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Finding the Tangent
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Normal Plane
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Osculating Plane
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Normal vector
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Binormal
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Difference between Normal and second derivative
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The three coordinate planes and their relations to the 3 vectors.
Foundation: Sweeps along piecewise linear paths.
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How to properly join cylidrical tubes at an angle.
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How to join prismatic tubes, so edges line up.
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"Azimuth" and "axturn".
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How to calculate the torsion minimizing azimuths.
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The "twist" parameters.
Closed prismatic loop.
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How to gracefully join the two ends so that prism edges line up
- How well does SLIDE do this ? Test cases: Hamiltonian cycles on cube, dodeca, face-diagonals of dodeca, ...
Sweeps along smooth curves.
- Any smooth curve in computer graphics becomes piecewise linear at some point.
The sweep parameters in SLIDE.
New Homework Assignment#2: (Due 9/13/07: 08 am, electronically)
Install SLIDE, and create a 5-variable Venn diagram with 5-fold symmetry.
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