CURVE(6D) CURVE(6D)
NAME
curve - fast interactive cubic curve display
SYNOPSIS
/usr/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 until the menu option
you select is highlighted and release the button. A menu
option may have an arrow which indicates a rollover menu is
available for that menu option. To bring up a rollover
menu, continue holding down the right mouse button mouse
button and move the cursor to the left or right of the
currently highlighted menu entry. The rollover menu will
overlap the first pop-up menu, and the choices on this
overlapping menu will be active.
To get rid of all menus without changing the display, move
the cursor clear of all menus and release the button.
Pop-up menu operations
To operate the curve, select the curve window for input.
Press and hold the right mouse button. A menu of operations
appears. Move the cursor to the menu entry for the desired
mode and release the right mouse button to select it.
Select motion on the menu to give each point a random
direction and velocity or, if the points are already in
motion, to stop the motion. Basis, linestyle, and precision
each present their own rollover menus. Vary their
parameters by making selections from the rollover menus.
Markers turns on and off the basis point markers. Smear
alternately simulates families of curves and restores the
single curve. 3-D 2-D selects a 3-D box or the initial
plane for the display.
Initialize reselects the initial state. Kill (from the main
menu) terminates the program.
Left and middle mouse functions
Initially, the left mouse button is tied to the Add Point
function, and the middle mouse button is tied to the Delete
Point function.
The left and middle mouse buttons can be tied to one of
three functions: Add Point, Move Point, and Delete Point.
To tie an operation to one of these three functions, use the
right mouse button to bring forth a pop-up menu. The
Page 1 (last mod. 8/20/87)
CURVE(6D) CURVE(6D)
choices on the pop-up menu labeled left mouse and middle
mouse have associated rollover menus. There are three
choices on each rollover menu, each choice corresponding to
the Add, Move and Delete Point functions. Picking a choice
on a rollover menu ties the function to a particular mouse
button.
Add Point places basis points on the plane. For each new
point, move the cursor to the desired location and press the
mouse button tied to the Add Point function. 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.
Delete Point removes basis points from the plane. If the
mouse button tied to the Delete Point function is pressed,
the nearest basis point to the cursor is removed.
If the mouse button tied to the Move Point function is
pressed, the point nearest the cursor and the affected part
of the curve are dragged.
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.
In Move Point and Delete Point modes, the basis point and
spline closest to the cursor is no longer colored. When it
was colored, it was easier to determine which point you were
going to move or delete.
In 3-D mode, picking locations takes place in 2-D screen
space.
HARDWARE REQUIREMENTS
Eight bitplanes and 1.5 Megabytes of memory are required to
run curve.
ORIGIN
Silicon Graphics, Inc.
Page 2 (last mod. 8/20/87)