[QUESTION / REQUEST] Using draw order to improve perspective visualization

Hi everyone,

I’m dealing this days with a model in which overlaps lot of curves and surfaces. Sometimes is necessary for me to display surfaces and the curves at their edges at the same time. I thought that Draw Order commands could help me in that task. The problem appeared when I started rotating the perspective view and noticed that if I Bring To Front the curves, no matter where they are in space, they will always will appear on top of the surfaces.

Could it be possible to have the same behaviour that we have already en 2D but modifying it for 3d views adding some kind of depth checking so we don’t mess too much with the view Display Modes behaviour?

I understand that it could be tricky or even not possible, as the draw order function overrides the depth checking in rhino viewports with an user imposed one. But as I don’t know how can this affect the current draw order behaviour I would like to ask.

Thanks in advance.


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Hi Angel,

Can you post a simple example file with a description of how to see exactly what you’re mentioning? A screenshot of the issue would be great as well. I want to make sure I understand the request before filing anything. My guess is that you want draw order to persist unless the chosen objects are occluded over a certain Z depth relative to the view.

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Hi @BrianJ,

Thanks for your answer. Please find attached a capture with the mentioned behaviour.

As you can see the red curve is on the white surface and was “brought to front”. After that you can see how it is displayed in front of the green surface that is closer to the camera than the white one (as shown in the ZBuffer capture).

So my question was if it is posible to modify this behaviour to be able to use Draw order commands properly in 3d views without messing with the position of objects in 3d.

Best Regards.


Hi Angel,

I made a simple 3dm file attached here. Can you explain the need to use BringToFront for the lower red curve as opposed to leaving the draw order alone as seen with the top red curve? Is this just for other views where you want the curve in front? I think the top red curve shows up on the surface it’s coincident with while also being occluded by the surface in front.
DrawOrder.3dm (301.8 KB)

In this case is not, but if the red line is coincident with the edge of the surface sometimes is good to push the curve to front for visualisation purposes and to make the selection of the element faster. In certain models that would help to send captures and coordinate with consultants or just to create document modelling processes.

So some cases that I can summarize:

  1. Curves coincident with edges of a surface.
  2. Several curves coincident but with different lenghts and you want to put one of them in top of the other in the visualization.

…And let me think more because there should be some more.

Thanks for the reply and support :slight_smile: