Actually splines is the chain of vertices that represents the poly-line.
It can varety from single point and line to long line strip.
Splines can alos be closed when the starting point matches the end point of
the same spline.
Splines were designed the first in ZModeler long before other stuff and were
aimed for simple creation of surfaces.
Note that I strongly recommend to save your work before you start working with
splies in the scene, then delete all splines when you have done with them and save
your work after deleting splines. That will save a lot of your nervs.
Also, splines are directed poly-lines and has a so-called First vertex. This
vertes is drawn bigger then other vertices and represens strating point of splines.
All spline create tools are in the
Create...\Spline...\ subbrance in the menubar:
They are:
Point - creates a single-point spline with left click.
Line - creates a two-points spline. Note that you SHOULD NOT hold down
mouse button when you create splines
LineStrip - creates a sequence of lines, a so called linestrip. You
should Right-click to stop creation or click on existing first or last point
of ANY spline.
NGon - creates a closed spline with defined amount of vertices.
The following picture illustrates several types
of splines:
1 - Point spline, 2 - Line spline, 3 - Linestrip, 4 - Closed Linestrip, 5 - NGon with
16 points
Also it haven't been concerned before, but there
are two levels for splines: It's a level of Splines and level of Spline vertices.
To switch the first one you need to switch to objects level ('4' key) and then press
Splines button (`) in toolbar, that the both objects and splines buttons are down.
To switch to Spline vertices level you need to switch to vertices level ('1' key) and
press splines button (`). In the first mode you edit the spline as whole, but in the
second mode you can edit splines vertices one by one (moveing them for example). This
you need to know before the next topic:
Splines supports most of standart modifications from
Modify...\ tools of menubar, and all that modifications can be applined both to
any spline vertex or to spline as whole, by switcing to according level.
But there are also several specific modifications for
splines that are in Modify...\Spline...\ subfolder in menubar:
They are:
Insert - inserts a vertex into spline (with a left mouse click) and starts moving
this vertex (don't hold left button down) until you left-click again for newer vertex
or right-click to discard creatin of this vertex.
Open - deletes an edge in spline and "opens" it. Thus, if you click on an edge of
Line-spline it will be converted to two point-splines; if you click on an edge
of unclosed line-strip spline it will be converted to two splines; and if you
click on an edge of any closed spline that it will become unclosed:
The manual-drawen blue circles are the points
where I've clicked to open splines. You should note that in several cases the
First vertex of spline has changed.
Connect - connects start or end points of any splines and, in fact, this
tool is backward fot Open tool.
NOTE, that if you connect starting and ending
points of the same spline, than it become closed; if you connect start and end points of
diffenrent splines than these splines will be united into one line-strip spline. Alos,
you can't connect to intermediate points of splines: only start or end vertices.
It's worth to concern standart tools that work with
splines. I'll describe only Move tool:
What I'm pointing to is a small difference when you
move objects' vertices and splines' vertics. The last one has an aspect, a so-called
Auto-uniting of nearest points. That means, If you drag (move) splines' vertex over
other start/end vertex of any spline and release left mouse button (drop the vertex), than
program will ask whether you want to unit the nearest points. As a rule it's neccessary to
unit these nearest vertices. After uniting these vertices they become the single shared vertex:
You can also make some experiments modifying splines,
deleting splines vertices and others.
As you might noticed, splines has internal snapping when
you create them and the spline auto-closes with start or end point of any spline. But
there are other snapping tools provided with ZSnapper plugin. It has two valuable
snapping tools: snapping to objects' vertices and snapping to splines vertices that
woks both while creating and modifying splines:
On the image I've activated them both. The one
on the left is snapping to splines' vertices other is snapping to objects'
vertices. Also make sure that edit axis switched from Z to any other,
since snapping will not work when midifying in Z axis.
Now you cna create splines and see that vertices
are snapping to other splines and objects vertices. Thus you can create a spline that, for
example, lies over the mesh in 3D space and you don't need to move vertices one by one to
place them as closer to he mesh as you only can - it will be done automatically:
As you can see, the just-created spline exactly lies
over the 3D object exept first and last vertices that I've created aside the object to show
how the snapping works.