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How to Control Layer Order / Visibility?

Posted: Sat Apr 14, 2012 7:47 pm
by bkkbuilder
There doesn't appear to be a way to assign what order layers render in. It seems whatever object was edited last comes to the top and is most visible. Is this right or am I missing something? It doesn't seem very functional to have to edit objects to bring them to the top and as far as I've seen I can't have a layer draw above another layer.

In my home plan I'm getting the foundation drawing over top of windows and obscuring them. Any way to control this? Is there a "touch" command that makes selected objects "last edited" so they come to top?

BTW I don't know if AutoCAD works this way or not as it's been more than a decade since I've used it, but every other vector drawing program I've used allows ordering the layers so that you can determine what will over draw on what.

eg. I just edited the position of the brick wall under a glass brick partition. Now it seems I have to go back and fake edit the glass bricks as otherwise in the drawing they are obscured by the bricks under them. I have a hard time believing that AutoCAD would force me to fake edit items to make them stay visible.

Re: How to Control Layer Order / Visibility?

Posted: Sat Apr 14, 2012 8:18 pm
by andrew
Layers have indeed no influence on displaying order whatsoever in QCAD or CAD in general. Layers are a logical concept used to add information to an entity: a line on layer 'walls' might be part of a wall, a line on layer 'gas' might be part of a gas pipe.

Using layers in CAD to control the drawing order would not make any sense since a group of entities in the front might have entities on the same layers as a group of entities in the back. This is one of the major differences between CAD and other drawing tools.

Ideally we would have a a different concept in CAD to control display order. And that concept would have to be supported by the underlying file formats (DXF,DWG) as you don't want to redo everything once the file has been saved and reloaded.

The only way to do this in DXF/DWG is to change the order in which the entities are stored. This is the same order in which the entities are displayed. An entity moves to the end of the list when it is edited and therefore to the foreground.

QCAD 2.2 (Pro) has a tool to move entities into the back or front of others. In QCAD 3 (Pro), you can additionally control the display order by entering a level in the property editor.
QCAD 2.0 (Community Edition) does not offer any display control other than the admittedly clumsy one you have mentioned.