Spline question

[ftown]

Does anyone know how to make splines mathematically, in other words create perfect circles, or arcs, or spirals, out of splines? I'm creating motion
graphics with LW and I'm using splines as a guide for the motion of the design
elements, problem is the splines that I create by hand aren't that smooth.
I tried using the spline cage plugin and chopping off the bottom circle, and that worked fine, but I need much bigger arcs and lengths than just one circle. I tried creating splines with snap to grid on and that is a liitle better,
but still really tedious. Also, is it possible to make a spline have a 90 degree
angle in it? like in AE splines when you alt click the point in the graph editor?
TIA,
fred

[Silkrooster]

Create your circle using the disk tool. Kill the polygon (k shortcut on keyboard), Select all the points, use the create closed spline tool (create>curves>more>make curve>make closed curve), and you will have a circle spline.
Silk

[Surrealist.]

To the other half of your question the answer is yes.

You can start a curve from anther curve by selecting one of the points on it and continuing to create a curve by selecting other points as you would normally. This will create a sharp edge. You can later smooth it by using the curve smoth tool should you want. (In LW9 this is in the detail tab and by default there is a curve group.) Another way to create a sharp edge is to select a cuve in the polygon selection mode then switch to point selection, select a point and use the split tool to make it into two curves yet still joined.


Another useful tool here is the control points. If you create an extra point at the end of the curve you can activate the End Control point - end of the curve or the Start Control Point - start of the curve. This toggles on and off and what it does is makes the end point a controler like in bezier curves.

This would be helpful to control even the sharp angle as in the picture I provided where my sharp angle is actually an intersection. The picture shows the polygon selection mode with both curves selected which gives you the dotted line. You use to drag tool to adjust.

Also do not forget about the bezier tool for creating curves. This gives you bezier control of your curve creation.

And one last thing. Also there is a tool called BG Conform. yet another way to conform your curves in a foreground layer to a primitive shape(s) in the BG layer.

[Silkrooster]

You know, I did not even see the other question. :foreheads
There are a couple of ways you make a 90 degree bend with a spline.
1) Select the spline, then in point point select the point where you want the bend or add a point where you want the bend making sure it is selected, Use the split tool.
This will create two splines from the original and is like what surrealist mentions. This type of spline is also how the bezier tool will create a spline once its dropped.
Down side of this type of bend is the rail extrude will not continue once it reaches the end of the first spline.
2)Add a point as close to the point you want the bend, the closer the two point are to each other the sharper the bend, they can be overlay each other, just don't merge them.
This type of bend rail extrude will continue to the end.
Silk

[Sensei]

Try EasySpline's http://www.easyspline.com true Bezier tool.. :)

[SPINQUADDER]

since we're talking about splines how about this question.......I have a closed cuve (spline) but I want to break it where its closed, is this possible? Here's a pic. Thanks

[Sensei]

With original LightWave it's nightmare to do, usually requiring complete recreating spline (select curve, press k to remove polygon but doesn't delete points, and making new curves using these points).. EasySpline has special tools for this like Smooth Symmetry Spline On/Off and Smooth Spline On/Off..

[Silkrooster]

since we're talking about splines how about this question.......I have a closed cuve (spline) but I want to break it where its closed, is this possible? Here's a pic. Thanks
you normally get an error, when spliting the beginning/ending point. However can add a point and split it there. It is possible to end up with more than two splines as it stops at the the beginning/ending point, but selecting the two short splines and hitting shift z will merge them together and you end up with two splines. If the two splines look sharp where they meet, you can select detail>curves>smooth.
Silk

[SPINQUADDER]

thanks

[LightFreeze]

for the original posters first question, have you looked at Plot 1D and Plot 2D, they are in `more primitives`