NURBS Curves for trueSpace7.61

3 nodes are added to a scene when a curve is created.  The Control Point Mesh(CPM), the curveShaper and the curve mesh.  The control point mesh, CMP_*, has the control points that determine the shape of the curve.  The curveShaper translates the control points into a curve shape for the curve node.  The slider controls the resolution or smoothness of the curve.  The head or start of the curve is represented by a small cube.  The indicator follows the curve, but will interfere when point editing the control points mesh, so there are buttons for connecting and disconnecting the head indicator.  The freeze curve button removes the control point mesh and the curve shaper from the scene, effectively freezing the shape of the curve.  Do not just delete the curveShaper or trueSpace can become unstable and crash.

The curves are really cone meshes with the faces and most of the edges set to be invisible.  You edit the curve by point editing the control point mesh.  The CPM looks like red bezier handles, but is also just a cone mesh.  To edit the shape select the CPM and enter point edit mode.  Select all the vertices or edges of a "handle" and use the transform widget to move, rotate or scale them.  Change a control from smooth to sharp by selecting and moving just one of the handle vertices.  A closed curve can be simulated by moving the ends of the curve together and lining up the control handles.  Real closed curves are not supported.  The end handles have 2 points and the middle handles have 3.

If the control points are difficult to move, exit PE mode and push the "disconnect head" button on the curveShaper.

The original author of the program used to generate the curves is Rob Bateman.  Link.

This button will open a panel for loading curves from trueSpace scn and cob files generated from the modelside or earlier truespace versions.

Save curves in tS6.6 format.  The version 7 format has a lot of extra information and will slow down load process.

The scn and cob files must be ascii format.  JScript only reads ascii text format files and has no check for binary format files.

The panel has a slider for controlling the initial curve resolution.

This has not been tested with closed curves.  It was designed for open curves only.

October 9, 2011 - reads bezier curves from TurboCAD dxf files.

This button will convert the selected polygon to a curve.

The Polygon Draw tool will create a polygon with good vertex order.  Make plane and draw on it.  Select the poly and push the button.

May want to center the axis by 1) axis tool  2) reset axis 3) axis tool again to hide it.

Push this button to enter a special vertex selection mode.  In this mode you select vertices one at a time and they will have a red line in between each selected vertex that represents the final curve.  Right click to exit this mode and create the curve.

Push this button to enter a special mode for adding control points to the control point mesh.  After pressing the button the handles will disappear and the previously invisible line segments between the handles will become visible.  Select one of these line segments and a new set of control points will be added to the center making a new handle.

Select the vertex representing the root of a handle and push this button to delete the handle.

Select one of the vertices at the end(or start) of the control point mesh and push this button to extend the length of the curve with a new set of control points.

Used to create a series of sweeps along a curve path.  An imperfect, but usable uv mapping will be created with the sweep.

The mesh must already have uv assigned to set number 1.  I believe this is true for all meshes created inside of truespace workspace.

The face that will be swept must have other faces connected to it.  This is needed because the script uses the expand and contract selection commands when creating the uv values for the final mesh.

The mesh must also have no rotations in world space.  Use the freeze transform script before entering PE mode or use the axis tool, normalize rotation tool and then axis tool again to close the axis.  Flatten axis tool may also be needed.

The control point curve was preventing selection during this capture so I used the "Invisible" check box on the node so that the curve was easier to select in the 3D view. 

Now enter PE mode and select a face.  Push the button and the script will wait for you to select the curve mesh.  After the selection the face will be swept once for each curve segment and cylindrical coordinate uv will be applied to each new section.

The face should be lined up with the start of the curve.

The number of curve points controls the smoothness of the sweep. 

mesh editor settings - preserve unwrap off maybe needed

The curves are based on cone meshes because of their consistent point index order.

It's easier to use vertex snapping to vertices than to snap to edges.

Some uv editor script commands will crash truespace if the uv editor window is not open.

Moving a point selection is enough to change the triangle indices.  The vertex indices are fine but the triangles get scrambled.

Update: Jan 14, 2010 - bug fix

Modelside, tsx plugin for converting a nurbs patch to a quad polygon mesh.  Each of the patches for a multi-patch nurbs surface will have to be converted separately.  Exit point edit mode and use boolean subtraction on the mesh to clean it up after the conversion or use heal vertices in workspace.  This will remove any seams caused by the nature of nurbs geometry.  This plugin should work with truespace version 5.1 and up, but hasn't been tested.  The nurbs rebuild patch plugin on this page can be used to control the density of the final mesh.

Modelspace NURBS curves and patches plugins link.