Screw tutorial

This tutorial shows how to extrude around current view axis with drift parameter.
Home address for source code of meditor is:
This service is similar to other extrude around services, i.e., this depends on theta and phi divisions and number of turns. The difference is new parameter called drift. This drift parameter introduces a perpendicular motion following current line of view, so all extrusion can produce a closed path if drift parameter is zero but it can produce screw like extrusions if non zero value is used. One can change values using '&' key. In general, to produce closed extrusion following extrude around services, one should use #theta as 1.0 but for screw like objects, this will also control how many turns will be computed and this is mostly larger than 1.
Create a simple circle and move central vertex outward. Now move and select vertices as indicated in next image.
Now change the number of divisions to be created, just push '7' and change value to 128 as next image.
Change drift parameter to 0.2 using '&' as next image.
Change current view using 'd'. One should notice, the extrusion axis is y as in next image.
As I want more than one turn, I change it to 5 using  '6' command.
Once parameters are correctly enabled and the basic mesh is created, the service can be called using command window->actions as indicated below. Use first button under label "Extrude around". This is simple extrusion around view axis with no deformation envelope.

After that, main window should appear as next image. Select those unwanted vertex and delete it. Use edit mode to select vertex and delete it using 'Del' key.

Just to check if drift parameter worked, change current view as indicated in next image.
Now, to see simple rendered image, just push ALT+F10. That should appear as next image after few zoom out command.
That is all folks!