Back face? Front face? How do you tell?


#1

When we talk about front faces and back faces, are we talking from the observer’s position or the objects?

(If I design a house with only one room (four walls), should all the front faces face outward, and the back faces would be the inside faces? )

I want to make the faces oriented correctly, but with an object that has front walls and side walls and back walls, where is the “front” supposed to be?

I appreciate your help.

regards,
leaning


Why so many grays?
#2

By default, face fronts are white and face backs are light blue, although you can change these colors. Face fronts should be exposed to view; face backs should be turned away from the camera. In the case of a closed (solid) shape, such as a cube, it should appear white all over. All the blue faces are turned toward the inside of the cube.

You can reverse faces with the like-named command on the face context menu (right-click > Reverse Faces. You may choose to turn all other faces to the same orientation as a selected face by using right-click > Orient Faces.

Avoid painting your models with a texture or solid color until you are satisfied with the basic geometry and no longer need to refer to the face front and back colors. If you do paint an object, you may still see the face colors by using the Monochrome style setting.

Four walls would be like a cube-in-a-cube. The space between the faces is the “inside” of the wall. So turn all blue faces toward the inside (unseen side) of the wall, leaving all the visible faces, both inside and outside of the room, white.

-Gully


#3

I found it helpful to change my back color to something other then the light blue default. Here I have my back color set to a green color.

Here is how I change it in Styles window.


#4

Fine, but personally, I find the default blue face back rather hard to miss. Indeed, it fairly jumps out at me.

-Gully


#5

One of the first things I read in a book on using sketchup for 3d printing was how the author found it helpful for people new to sketchup to change the back color to a bright color like orange. Being new myself I tried it and found it helpful. After working with DaveR a bit and seeing him using a green for his back face I switched mine to green as I found it more pleasant to look at.

It’s just something I found helpful starting out so I thought I would pass it along. Maybe now that I have a little (very little) addition experiance with SU I would find the default blue a little more noticeable then I did at first.


#6

OK.
I set the back face color to green (just wanting to fit in),:slight_smile:

I make a cube. As I rotate around the cube, the face that is toward me is white. I like that.

But the faces that are not toward me (the two sides) are light-grey, and the back is dark grey ( almost looked like the green, but that doesn’t match your explanation, so it must be dark gray.)

Ok. How can I stop that behavior? I want green for back face, white for front face, and maybe a few patterned dots or something for the sides/back, but NO colors. I looked at View>Face Style but none of those worked. Too many shades of blue and gray and shading all working at the same time for me.

Any ideas?

regards,
leaning


#7

Yeah. The thing is, except on, say, flat shapes you draw on the ground plane, a visible face back is essentially an error, so I keep on the lookout for them. If I encounter a face back on my model, not only do I see it, it makes me cringe and grind my teeth. I can’t stand to look at it. I reverse it immediately. My skin crawls just talking about it.

Still, it’s entirely a matter of choice, and I’m aware that such notables as, for instance, @DaveR and @slbaumgartner, use colored face backs.

-Gully


#8

Me too. But actually, if the model is to stay within Sketchup and not to be exported for rendering or 3D printing, back faces are not an issue.

Anssi


#9

I use the green back face color because for me that color is easier to see when there are very tiny holes.


#10

I find that the visibility of the default back face color depends too much on my eyesight, display, and the orientation of the face relative to the camera. Unless I orbit around, it is easy for me to miss badly oriented faces. So I use a garish green back face color that I can’t possibly overlook.


#11

I guess I have reason to be proud of my cones.

-Gully


#12

I have found the same. Generally, the default is easy enough to see, but in some cases, washed out monitor, small geometry, sleepy eyes… can make the default hard for ME to see. I use a bright purple that is hard to miss and looks nothing like a white face in shadow.


#13

Thanks for the discussion. I “went green”. :slight_smile:

Is there a setting to stop that shading as you rotate around a model? (ex, for a cube, the face toward you is white, the two sides are light grey, the back is dark gray) and replace those colors with a pattern (dots or stripes, for example) (front face no dots, side faces spaced dots, back face less spaced dots)?

regards,
leaning


#14

Yes. In the Shadow Settings dialog, check the “Use Sun for shading” box and use the Light and Dark sliders to adjust the shading to the least possible. On my monitor, the face colours match the colour palette swatches best when Light is set to 0 and Dark to 80.

Anssi


#15

Anssi.

Thanks! That’s exactly what I needed. “shadow color” and “face color” where all running together in shades of light blue, white, and gray. Now, the faces are white and green, and all those extra face colors caused by the shadowing are gone. (Plus, you don’t know how many faces I was reversing, because I was equating that shadow color to the back color.) :slight_smile:

Sweet!

regards,
leaning


#16

Keep in mind the shading can be useful when you are modeling so you may not always want to be rid of it.


#17

I always approach my modeling from a real world perspective and work back from there only as far as makes sense.

For example: If I was drawing a one room house, where one would be viewing both the interior and the exterior, I would make the walls with a space between producing and interior set of walls with the front face facing inward, and an exterior set of walls with the front face facing outward. Any windows and doors would have a jamb so to speak. The only time I use single face geometry is when doing glass.

If doing just an interior or just an exterior, I draw just a shell with the front face being that which is viewed.


#18

Hi Aaron,

I see in the last version of SU that it is now possible for us visually challenged people to change the colours for the axis and such under SketchUp Preference. Would be cool if we could swap the default colours of our faces in the same settings in the next update.


#19

Why not just edit the style to change the front and back face colors to suit your needs? That feature has existed for decades.


#20

Yes I do it already so it is not the biggest deal. But it would be nice to have a “native” option just for my own system. If my colleague imported my .skp file he would see his own default face style when opening my/our model.

Edit: My last sentence is not very clear. It should say “I would like that my colleague can see his own default backface style and not mine when opening a model that we are working on”. Sorry for that.