To be or not to be...opaque

I’m sure some of you will have a clever way of dealing with this problem.

When you create an object with glass in it, there are often some scenes you want it to be translucent and others where you want it to be opaque. In a perspective interior scene you might want to see the effect of sunlight coming through glass. But when you show elevations, you don’t necessarily want to see interior detail as it tends to confuse the image.

I can think of complicated ways of doing this. You could have two versions of a window (say) ascribed to different layers (oops, I mean tags) and have the appropriate one visible for the scene. But is there a more elegant way than doubling up on geometry?

Have you tried to create a new style with transparency disabled?


You could also paint a different material on each side…clear with zero opacity on one side and the blue glass texture on the other.

For room models I often have the interior textures on the inside room faces and make the exterior wall surfaces totally transparent which allows me to see inside when orbiting on the outside, but when in the room it looks normal.


I have in the past put a black box of sorts inside the building to black out the windows. I’ve thought about putting a black-out surface between the glazing and put it on a layer to toggle on and off. That might allow applying a “color ramp” or “graded wash” like I’m used to doing with windows in PowerCADD like this.

I haven’t actually tried it out though.

I like this idea but have struggled finding out how to implement it. Can you help?

Paint each face (inside/outside) with a different material (it doesn’t matter which material is on the outside) and then lower the opacity to zero on the outside material in the editor. I find it helps in many situations and eliminates the need to hide walls or make section cuts. Although section cuts may have to be part of the final file for use in layout etc.

1 Like

I use a different approach of leaving the exterior, and bacf faces ‘default’ and paint the ‘group’ with a ‘flat’ color set with 0 transparency…



Looking at that window which has translucent glass externally, what does it have internally? That’s an element analogous to what I am trying to do because I want the sunlight to come in when looking at the interior but the glass to be opaque when seen from the outside.

The SU default which is white outside and blue inside is shown as having a different inside and outside material colour in the palette. I have not found how to separate inside and out. So if I paint a surface as translucent glass, it shows the one colour and is translucent both sides.

sorry, for just a window…

one_way_glass.skp (26.8 KB)

set the shadow properties…


You have glass that has a thickness, which of course it would have in reality.

I downloaded your drawing and created a no-thickness pane and found I could change the front and back properties to what I think I am after using Entity Info. is that in fact the standard method?

without thickness, although I never would create glass this way…

one_way_glass.skp (28.2 KB)


@john_drivenupthewall was painting the various faces with the paint bucket one at a time in his demo, but I’ve used entity info before. I will point out something about entity info that made me crazy till I figured it out: if you have anything more than just faces selected, it won’t show you front/back face colors separately

Screen Shot 2020-02-03 at 11.58.21 AM

Selection tools can help select only faces to use entity info on multiple faces at a time.

OK, so this prompted me to actually try the graded wash thing. Went into Photoshop and created one, imported it as a texture and put it in as a two faced surface inside the glass as outlined above. Results like this:

Here’s the texture:
Grey Ramp 256p


and you couldn’t feed him in…

Maybe it shouldn’t show an icon at all if you have multiple things (5 Entities in this case) selected?

That would be more consistent with how it handles selections with multiple tags.

When you apply a material to a group or component, both sides of faces are painted unless they already have a material applied to the actual face.
When you paint a 1 m cube component, the material browser will report a 12 m² area for the material.

I hadn’t realized that, or at least thought about it.

I was going to say other programs can show “various” or “multiple” in a selection, but actually SU does. It’s the fact that lines don’t have back faces, so when they’re included, it won’t show any back face color.

If just faces are selected, is shows like this:

Screen Shot 2020-02-04 at 10.25.11 AM

And you can use Entity Info to edit all the colors as once:
Screen Shot 2020-02-04 at 10.25.51 AM