The Design Mentor program demonstrates Bezier and B-spline curves and surfaces. It was created by Dr. Shene and his students in the MTU Computer Science department (www.cs.mtu.edu/~shene/NSF-2/index.html).

Use right-click and "Save Link As..." to download the curve program:

- for Sun: curve (You may need to set the execute permissions after downloading.)

- for Windows: curve.exe (You may need to also download Glut32.dll, Glu32.dll, Opengl32.dll, Gdi32.dll)

To run program:

1. Start program.
2. In “Display & Tracing Options” dialog box, set “Control Polygon” and “de Casteljau’s Alg” to be displayed. Dismiss dialog.
3. Select Edit ->Create. Click on graphics window to create Bezier curve control points.
4. Move slider on right up and down to observe influence of control points as parameter changes.
5. Select “Curve: Bezier”-> “Change Current Curve to” -> “B-Spline”.
6. Select “Degree: ..” -> 2.
7. Select “Curve: B-Spline” -> “Show Curve Segment” -> “With Clamped Knots”. Observe how the curve is different from before?
8. Move slider on right up and down. Observe that now only the three closest control points effect the curve at a time.
9. Experiment by repeating steps 6-8 with different degree values.

Use right-click and "Save Link As..." to download the surface program:

- for Sun: surface (You may need to set the execute permissions after downloading.)

- for Windows: surface.exe (You may need to also download Glut32.dll, Glu32.dll, Opengl32.dll, Gdi32.dll)

To run program:

1. Start program.
2. In “Tracing Window”, set “Tracing Point” and “Calculation” to be on.
3. In yellow box of “Tracing Window”, drag purple circle around to set different values of U and V. Observe how surface points are obtained through a series of Bezier curve calculations. First one set of Bezier curves is evaluated (red ones). Then the resulting points from each of these is used to do another Bezier curve evaluation (blue).