FR - Back Edge Blocking Material


Would love to see a material that can block back edges… I often use SU for technical / shop drawings and when isolating building sections I drop a white plane behind the cut I’m isolating for the shop. Often I want to show whats inside the current view - but seeing too far into the model can be confusing.

What would be an interesting addition is to have a material bundled with Pro that would block back edges behind it…


Back Edges are controlled in the Styles Settings. And that might arguably be better, in that you don’t need to keep track of which materials happen to block, or allow, their visibility.

There is also a Styles tool bar menu that has a back edges button, which allows for faster access if you want to set that up.


Alternatively, Have you ever tried the ‘Create Group From Slice’ command?.. which is available from the 'right click context menu of a selected section plane.

If not, give it a go… I often find that it’s a nice way to copy/save out the section cut info in a way that allows you to move it to some other section of the model space—maybe even placed on it’s own layer for easy visibility control.


Hi, yes, I know how to control back edges. How to create slices, how to control visibility, etc, etc. I often have several styles active in a model (and sometimes overlay various model views in LO for effect).

What I am suggesting is a material that blocks them from view, so that you can see into part of a model, and not the whole thing. Alternatively one could isolate what I want with layers - turning everything off and leaving only a portion of the model on, or hide / show objects - but this get really complicated - especially as 1 item can’t live on more than 1 layer, and I have have parts that show in multiple views.


… A kind of clipping mask.

Layout has it, and it would be nice if SketchUp had something similar.

Nested section cuts within groups are another way… but as you say it gets tedious to set things up.

I’d love to see a Section Plane type of tool which can have user defined edges… but that’s leading back into the clipping mask idea.

We’ll see what others have to say on this.


Are you using Layout with your Backedges? It only works in raster mode so I never do that, though I also use the masks in sections to hide stuff in the back.


Yes, I mix up Raster / Vector depending on what I’m doing.
Here is a truss that I’ve detailed. The truss is in 1 SU model view, raster, back edges, the steel was embedded in the truss, but I isolated that with a layer, then turned it on in its own view, exploded it so I could turn the color to transparent, then made sure it was positioned over the truss in the right spot. Sometimes I’ll do this by pulling the steel in front of the structural components - but in this case I wanted it ghosted.

And a detail of a purlin end:

Its useful, sometimes to see what’s happening inside - but if there’s alot going on behind it - it can be confusing.


The truss drawing is nice and your workflow is probably something I would have done.
Have you tried playing around with different styles for different views? You may be able to achieve the ghosted effect via xray mode without having to explode it in layout. Depends on the final look you need.

The only way I can think to solve the “too many back edges” issue shown in the “Typical Purlin @ Rafter View” is via stacked view ports. Here is my imagined workflow.

In Sketchup:
*Create 2 different styles one with back edges on one with back edges off.
*Create the scene you want to see and duplicate it.
*In scene 1 hide all the elements that you DON’T want to show back edges and assign the back edges ON style,
*In scene 2 hide all the foreground elements that you DO want to show back edges and assign the back edges OFF style,
*Save and send the file to layout

In Layout
*Place view port 1 and configure it to show scene 2
*Copy view port 1 to create view port 2 and place it on top of view port 1 in the exact same position.
(I tend to assign each view port to its own layer so you can hide/lock them individually, which helps with editing).
*Configure view port 2 to show scene 2 in Rasta rendering mode,
*Turn the background off for view port 2 in the Sketchup Model > Styles tab.

That should get you the image you want. Whether its the best way to achieve it, i don’t know.


Mike, lovely illustrations as usual. I can see the benefit of your request. Things do get a little busy when you can see all of the back edges.


Thanks @benoldays - I often stack multiple viewports - but the goal here is not to hide / unhide components or groups - that’s too tedious and fraught with issues for large projects to be effective, as I would be chasing objects around that might change, be added, etc. Layers would work - but again, only 1 object on a layer kills the idea as members that work in both directions (posts, plates, etc.) would not be visible. I have also typed with multiple copies and grouping - but as these are shop drawings they are also used for material take offs and structural permitting - I hesitate to do introduce anything that creates multiple copies / chances for errors.



Actually, now that I think of it - perhaps a feature request that would solve my problem, and be useful to others would be to have a section cut that has depth… this would allow styles to remain as is, and you would control depth via an updated section cut function.

I’ve had a look at fog… not really sure how to make that work for this use. Unless I’m just obtuse with how fog is supposed to work - I can’t seem to get it to work consistently and be the same from view to view.


Yeah I feel your pain man. Some of the little things can be very overly difficult to achieve. Unfortunately I don’t know anything about the programming side of things to know whats possible outside of the standard/extension tool sets.

A “Fog” like tool that can be assigned to different things individually would be good. Things like profiles, back edges, shadows, materials, layers, etc. Then you could just set the depth they are cut from view as needed.


I think a special material for this would be very complex conceptually and not very intuitive. It solved one very specific problem but at the cost of redefining what materials are and what meaning they have.

I’d rather see a way to use different styles for different objects, e.g. by attaching styles to layers. Then one object could have back edges on and others not, and work regardless of camera position. This could also be used in tons of other situations, e.g. shaded and textured design to a monochrome/hidden line context whereas a back edges blocking material could only block back edges.


That’s a fair take - but styles should work globally - and until an object can be assigned multiple layers (tags), you would then need to remember / control what styles were assigned to what objects or layers. The beauty of styles right now is that I can have several pages of documents and with the same model I can show the model with different materials, detail, etc.

I think the better idea is a section cut with depth. That solves multiple problems and opens up lots of other possibilities.

I will post another FR.


Many 3D applications have a method of controlling the “depth” of section planes and elevations. Adding a “thickness” to section planes would perhaps be a good feature request.


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