abstract:In this tutorial I will introduce the curve-modifier and create a sculpted helix. The tutorial works with Blender 2.49b and Jass2.

intended audience:

  • Creators of “sculpted prims” for OpenSim and similar environments
  • Blender novice (low/mid level skills)

prerequisites (*):

  • download: jass-2 (binary distribution, contains blender-2.49b, python-2.6.4, primstar-1.0.0 and more)

related tutorials:

Separate Downloads:

(*) If Jass-2 is not an option for you, you can download the prerequisites separately:

  • download: blender (2.46 or newer, 2.49b recommended)
  • download: python (2.6.4 for Windows, 2.5.2 for Mac OS)
  • download: primstar (1.0.0 or newer) by Domino Designs


Hello and welcome!
In this tutorial I will introduce the curve modifier and create a sculpted helix.
Please take care to work in front view, otherwise you will face unexpected distortions.
I also assume that you start in object-mode.

In step one let us create a helix-curve.
I will use the screw-tool for this step.
start with an empty mesh.

Hit the space bar, then click: add, mesh, empty mesh.
Now go to edit-mode and add 2 vertices.
Hold down the control-key and press the left mouse button
where you want to create the vertices and then select the whole edge.

Note that the relative position of the vertices determines
how the helix will be oriented in the 3D-space.

Now locate the screw-function in the edit-button panel.
right below the function-button you can specify the number of turns.
I will set it to 3.
Then i click the screw button.

Use the alt-key, and press the right mouse button ,
to select one of the vertex edge-loops.
Use the delete key , to delete the edge loop.

Now we have a connected set of edges.
Let us select all vertices and subdivide them one time.
then smooth the curve a bit,
And finally stretch it along the z-axis.

Now go to: Mesh, Scripts, Edges to Curve.
By now we have created yet another object.
To see that ,
move the currently selected object upwards along the z-axis.
then go to edit mode.
You see that the object contains a path , decorated with a set of arrows,
all pointing towards the path direction.

Rename this object to: helix-path.
go back to object-mode,
select the secnd object ,
and delete it.
We do no longer need it here.

Now we have mastered the first part.
Keep the new path , in the background,
go to front view,
and add a cylinder sculptie.
Use 4 faces in X, and 16 faces in Y.
Set 2 subdivision-levels,
enable subsurf,
and ensure that you use the catmull-clark smoothing.

Unfortunately primstar sometimes makes wrong assumptions,
when you enter the numbers by hand.
Then it marks the numbers as wrong ,
by displaying them on a black background.

If this happens to you,
then de-crease one of the face-counts with the adjacent arrow-down-key,
and increase it again.
Now primstar has corrected the data,
and you ? can Build the object.

Let us inspect the cylinder in edit mode.
ro-tate the mesh so that it can later be enlarged ,
by scaling it along the x-axes.
Also make it a bit slimmer by pressing s, shift X,
and scale-down the cylinder-radius.

So far we have mastered the secnd-part.
and now we will proceed by connecting the cylinder with the path ,
by using a curve-modifier.

Go to object mode.
Then locate the Modifier-stack,
and add a curve modifier.

When the object is moved along the dominant axis, namely the x axis in our example,
then it actually will be stress=yes bended along the path.
And it also will be bended along the curvature.
Since our goal is to create a helix along the entire path,
we only have to scale the cylinder along the x-axis.
And its curvature will automatically follow along the path.
When the object-size along x exceeds the path lengs ,
then the object ends up in a straight line.

Let us see what happens when we apply the modifier right now.
First we get a warning,
that the selected modifier is not the first on the modifier-stack.

Note, that the modifier-stack is always processed from top to bottom,
And the order of processing influences the resulting mesh.
Applying a modifier further down in the chain, effectively is equivalent to moving
it on top of the stack. Hence the order of processing will be changed,
and unwanted distortions may appear, as we can see here.

Let us revert this step, and see what
happens when we just change the order of the modifiers.
You can do this by using the small up-down-arrow keys available on each modifier .

Indeed now we see the exact same distortion as before ,
when we applied the modifier .
Let us now-rearrange the original modifier order.
We will now apply all modifiers from top to bottom.
And now we no longer see any distortion.

When we go to edit mode, we also see that now all sculptie vertices
have been created.
Now we can safely bake the sculptmap.
Keep the default settings, and bake.

Now let us examine the baked sculpt-map.
Ensure, that you go to object mode.
in the UV-image editor click: image, import as sculptie.

Move the sculptie a bit along the x-axis,
and check it for errors in the mesh.
You also can Set smooth. This will let the object appear
similar to how it will look in OpenSim (or your preferred online world).
Unfortunately we face another bug in this step.
The object will be partially rendered in black.
To fix this, go to edit-mode, and immediately return back to object mode.
Now the display is corrected.

Now let us see, how this helix looks in OpenSim.

I have shown you ,
how you can create a helix , by using a curve-object.
The important step was about converting a set of mesh-edges , to a proper curve.

We also have seen,
how we can apply a curve modifier to a sculptied prim,
and we know now,
how we can examine the quality of a sculptie ,
before we actually move it to our online world.

If you have any further questions, please ask me for help.
And do not forget to send me a small donation, if you like this tutorial.

see you later!