DIRECTIONS:   In this applet, you create a triangular Bezier patch by dragging the control points control points to an appropriate location. You drag the point in perspective view on the image plane and move the point in and out of the image plane by using the A and Z buttons where A moves point directly on a line towards your eye so the point will not move apparently on the image screen and Z moves the point directly on a line away from your eye. Alternatively, you can move the point using the C and D buttons perpendicularly to the image plane, C moves away from you and D moves the point toward you. The patch can be rotated using the arrow keys, and you can zoom out and zoom in using the page up and page down keys. To see how the patch is created through de Casteljau's algorithm, select the Show Intermediate Points and then click in the barycentric coordinate panel.

The save/load button enables an editing window where you can alter the coordinates of the control points and cut and paste the coordinates into an editor for storage. The reset button reloads the applet to its initial configuration. The PERSPECTIVE/PARALLEL button toggles between the two different projections to view the patch. The resize button allows you choose the size of the Bezier patch you are creating (the number of control points you are using), initially you are manipulating a 4 x 4 grid of control points to create a Bezier patch that is 3rd polynomial in both directions (a bicubic Bezier patch). The last feature is the ability to color the patch by the root mean curvature, instead of coloring based on position. In the coloring scheme the coloring from low curvature to high curvature is blue, green, orange, red and then purple.