Quote Originally Posted by bnilsson View Post
You have all of my relevant code in the example. What is missing?
Knowledge what items represent. I don't want to go through all your code and learn it by trial and error. For example I don't know if you really need 4 points to represent a trapezoid or if those trapezoids have somehow "fixed" properties, for example always a 90deg. angle - then you just need 3 points, or fixed lengths.

However, the description in Assistant is a bit cryptic, so I will have to test different settings. Will a higher value improve?
It is nothing you may set. It's a value given by the view to the item's painting routine that tells it how far away the "camera" is from the item. The further, the less details may be seen, so drawing those details becomes obsolete.

I tend to have the same opinion. But the gv framework is so convenient!
I don't think it is an overkill. If you design the scene correctly, it will work fine. With a regular widget you'd probably want to have items as well.

Quote Originally Posted by bnilsson View Post
Where does the pos() come in?
It's set to (0,0) by default. The way you do it makes your items very complicated, especially if you'll want later to interact with them somehow. If you have a trapezoid, make it span from (0,0) to the width and height of the trapezoid and them move it into an appropriate position using setPos(). This probably won't yield any performance gain, but will it easier to implement the ShapeItem that doesn't use paths or polygons that are really slow to draw.

Secondly, can you apply levelofDetail to a high-level draw such as scene->addRect();?
The rectangle item probably doesn't use LOD, so no. You have to implement your own item for that. It is most essential for your trapezoids. Simplify things wherever possible.