NAME

curve − fast interactive cubic curve display

SYNOPSIS

/usr/people/demos/curve

DESCRIPTION

Curve rapidly draws any of several cubic curves.  All control uses the mouse and mouse buttons. 

To change the display, press the right mouse button to display a popup menu.  Move the cursor till the menu option you select is highlighted and release the button.  To get rid of the menu without changing the display, move the cursor clear of the menu and release the button. 

Add Point and Delete Point place basis points on the plane.  To add one or more points, select Add Point, move the cursor to the point locations, and press the left mouse button once for each new point. Each point will be labeled with a marker. As soon as four or more points are selected, they cubic curve they determine with the current basis is drawn. If Delete Point is selected, the nearest basis point to the cursor and the portion of the curve affected by that point are colored.  left mouse button will delete the point. 

In Move Point mode, the point nearest the cursor and the affected part of the curve are colored.  The left mouse button will move the point to the cursor.  Hold the left mouse button down to drag the curve. 

Select Motion to give each point a random direction and velocity.  Select Freeze to stop it.  Basis, Linestyle, and Precision each present their own popup menus.  Vary their parameters with the right mouse button.  Return to the main menu from any of these with Quit.

Markers Off turns off the basis point markers.  Markers On restores them.  Smear simulates families of curves.  No Smear restores the single curve.  3−D and 2−D select a 3-D box or the initial plane for the display. 

Initialize reselects the initial state.  Quit (from the main menu) terminates the program. 

AUTHORS

Rocky Rhodes and Herb Kuta

BUGS

The Bezier curve looks wrong if more than four points are specified.  It is not.  It is discontinuous, but that’s the way M. Bezier designed it. 

HARDWARE REQUIREMENTS

Eight bitplanes and 1.5 Megabytes of memory are required to run curve.

Version 2.5  —  April 22, 1987