This section demonstrate how to create a Coons Patch based on four BSpline Curves.
1. From the Create menu, choose a BSpline Curve, (Create -> BSpline Curve).
2. Draw a vertical BSpline consisting of four control points.
3. Draw a BSpline curve starting from the previous curve. Using Object Snap will allow the new curve to accuratly start at one of the end points of the previous curve.
4. Create the curve with four control points.
5. Create a third BSpline Curve starting at the other end of the first BSpline curve. Use four control points.
6. Close the shape with a fourth BSpline curve. This time using five control points.
7. Select all the curves.
8. To create the Coons Patch surface, choose the option from the Right Click menu, (Right-Click -> Multiple Selection -> Coons Patch).
9. The surface will be created between the curves.
10. The surface will update if any of the bounding curves are edited, rotate the view and edit one of the curves.
11. Set up contours at every metre, (Tools -> Contours...). Remember to press Generate before pressing the OK button.
12. Remove the surface parameters, (Right-Click -> Coons Patch -> Show Parameters).
13. Display the contours, (Right-Click -> Contours -> Show Contours...).
14. The contours will be displayed on the surface as in the image shown below.
