This applet is for spline(Hermite, Bezier, and B-Spline).
First, choose any spline you want to play with.
Sometimes, when you choose new spline, the spline alredy drawn may not
be erased.
In that case, you can just start drawing or click on the reset button.
Buttons and Choices (from left to right):
Choice1 - Type of spline(Hermit, Bezier, or B-Spline)
Choice2 - Mode. Adding or Dragging.
Choice3 - Smoothness at the joint of two segments(smooth or free style).
See
Course homepage
......... When you change mode to smooth, it will align according to the
order of the points.
......... Careful. Sometimes it doesn't repaint the picture. You may
click Botton1.
Button1 - Help line(point) mode. erase or draw help line(point).
Button2 - reset.
Blue fonts below are for direction how to draw.
Hermite Spline:
You need P1, R1, P4, R4 to make a segment.
P1 and P4 are points, and R1 and R4 are tangent vectors from P1
and P4, respectively.
You can click to place P1(or P4), and drag for R1
(or R4) while keep pressing the mouse button.
When you release the mouse button, the red help line will be fixed.
You don't need to redraw P1 and R1 for the next segment. It will copy
the last P4 and R4 by itself(with same magnitude). It will look there is
one vector at the joint, if you drag, you can see the difference.
Once you have segments, you can drag points by choosing drag from choice.
I used 4*R1 and 4*R4 instead of just using R1 and R4
to make the curves dramatic.
Bezier Spline:
You need P1, P2, P3, P4 to make a segment. You need 1+3n points to
complete the curve.
The green line means
uncompleted segment
due to lack of point(1+3(n-1) < p < 1+3n).
The line would start from P1 and end at P4. The other two points are for
controlling the curve in between.
First, place a point by clicking and releasing of mouse. When you click and drag, you can see the help line dangling.
Drag the red help line to the position you want and release the mouse
button.
Keep adding as many as you want. It will generate curves.
Once you have some points and segments, you can drag by choosing drag
from choice.
B-Spline:
You need 4 points to make a segment and the number of points should be
greater than 4 to draw.
Black dots on the line are knot points which you can't drag.
Place points by clicking. You can change the position
while you keep pressing down the button.
The points will be fixed when you release the button.
Like other splines, you can drag help points when you choose "drag" from
the choice.
The help points you can drag are small red boxes.
It may not work correctly on Netscape. It works Ok on appletviewer and
Internet Explorer.