Training guide level 1 - exercise 5-11 - question & help requested

Hello everyone,

I struggle through the Level 1 Training Guide on my own. I try and click a lot when something doesn’t work out, but sometimes I just can’t find out what exactly goes wrong / or different and how I can get exactly what is shown in the example of the exercise. That is why I would like help from someone for whom my question is undoubtedly a piece of cake.

This question is about exercise 5-11 (page 93) Drawing arcs (with earlier exercises I have also encountered this ‘problem’, but this is a good example). When I make the figure solid, no lines become visible to me, but they do appear on the example (the yellow example) in the book. The red version (version 1) is when I do it completely as described. I made the gray version (version 2) by first just drawing lines before I solidified the figure. Looks like the example but I am sure this is not the right way to do it. I suspect that somewhere in the settings of how my figure is visible I have to adjust something. Can someone help me with this? Thanks in advance!

Vriendelijke groet, Xandra

Hoi Xandra,
The red version is an “extrusion object”, not a polysurface, and as such doesn’t show the isocurves that you can see in the other versions. You can use the UseExtrusions command to change the behavior.

Typically, when you are creating enormous amounts of simple box-like objects, the viewport performance will be better if you use “light-weight” extrusion objects. In all other cases, you might as well use polysurfaces.

Note that when you create extrusion objects and later modify these by splitting, trimming, … they will automatically convert to polysurfaces. You can manually change the type by running the ConvertExtrusion command, though that only works in one way: from extrusions to polysurfaces.

Thank you Wim for your quick response. Apparently the wrong image was used in the course book, because the exercise was with ‘make it solid’. I changed the solid by hand into a lightweight, as you suggested. That works. I also tried to make the shape with a surface - extrude curve - straight to a lightweight object, but then I only got the outline. With cap I get it closed, but then the slot and the hole are also closed. Anyway, I will probably come across that in the course later on. For now it is nice to know that I did well, but that the picture in the book is different.

Just to clarify; Extrusions are the “lightweight” versions (= no internal isocurves) while a Polysurfaces are “heavier”. But in most cases that doesn’t matter (the heavyweight Polysurfaces matters more if you draw a whole city of buildings and…).

So go for the heavyweight Polysurfaces as your default.


// Rolf