This applet requires a browser which can run applets developed with the JDK 1.1.5 such as Netscape 4.5, appletviewer or HotJava. Instructions on how to use this applet are below. Also, this applet will take a few seconds to initialize itself before the initial surface is displayed, so please be patient.
This is an applet which displays two types of tricubic spline surfaces: a Bezier mesh and a B-Spline surface. Clicking and dragging with the left mouse button on the displayed surface will rotate the surface so that it can be viewed from any angle.

Initially, the B-Spline surface and control points are displayed. The B-Spline surface and its control points are displayed in blue, and the Bezier mesh and its control points are displayed in green if the "Display Bezier Surface" checkbox is set.

There are several controls displayed below the surface. These controls determine what is displayed, and allow the user to manipulate the surface control points. The B-Spline surface can be added or removed from the display via the "Display B-Spline Surface" checkbox. The Bezier surface is similarly controlled via the "Display Bezier Surface" checkbox. The control points can be added or removed from the display with the "Display Control Points" checkbox. Below the checkboxes are the control point editors. The left-hand editor will modify the Bezier surface control points, and the right-hand editor will modify the B-Spline surface control points.

The control point editors display an overhead view of the surface's control points. The control point editors are not affected by any rotation of the surface itself in the canvas above the surface control checkboxes. To move a control point in the plane of the surface grab a control point by clicking on it with the left mouse button and move it to the desired location. A control point is flagged as "grabbed" if the click was within 10 pixels of a control point. To move a control point up (move it in the direction normal to the surface) grab the control point with the middle mouse button and move the mouse. It doesn't matter where the mouse is moved, it just matters that the mouse is moving (because Java doesn't give me more than one "mouse button pressed" event I can't move the control point just on the basis of the mouse button being down). Similarly, to move a control point down grab the control point with the right mouse button and move the mouse. Mouse buttons can be chorded together; to move a control point in all three dimensions simultaneously grab a control point with a combination of the left mouse button and the middle or right mouse button.

J. Scott Hofmann
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Last modified: Wed Feb 11 11:14:15 EST 1998