All Coplanar.skp (163.5 KB)
I was under the impression that if all corners of a shape were on the same plane, it would fill in as a white surface.
In the attached shape between the hexagon & the rectangle, all points have the same green axis value of 5/16".
So, why is that not a surface? How do I make it into a surface?
Peter Enns
They are not coplanar. The ~ in front of each of the 5/16" means that the coordinate is approximately 5/16" A few of them happen to be the same value, but some of them are a different value.
Go into Model Info, Units, and change the length precision to 1/64th. Then you will see that some of the vertices are at ~11/32", which is not the same as ~5/16".
Thank you, Colin. I really appreciate that information.
Peter Enns
How can I make minor adjustments to the four points so that they all will be coplanar?
Peter Enns
For your example, you could use the Move tool and move the corners that are not aligned, in the āgreenā direction, until they are aligned.
My architect would be upset if I showed you the whole model. Iāve just shown you the image of the area of my concern.
In the image Iāve attached, A, B & C were all showing a green axis location of ~39ā 5 17/32. I moved D 3/64" along the green and it then also became ~39ā 5 17/32. The surface did NOT turn white. I then tried moving point D back & forth along the green axis. Still, no surface appeared.
Iām at a loss. Do you have any more ideas on how to fine tune it?
Peter Enns
In my video I donāt move the wrong corners by a given amount. I moved them until inferencing made them be exactly in the right place. Your two cases of ~39ā 5 17/32 are not the same.
You could change the document to show decimal units, and set the precision to 0.000000". That ought to show any tiny differences there are.
I typically model with a style that has edges displayed color āby axisā, which greatly helps reduce drawing objects out of plane, and finding what lines are not. Though infrequently there is something pesky that shows all on axis, but I have to redraw something to get the surface to be created.
FYI Color by axis has an error tolerance. Itās not impossible for an edge to color as on axis but in fact not be, to be only very close to on axis. Itās a useful tool for maintaining generally square models when coupled with inferencing and for checking for big errors. But cannot be considered a definitive measure of āsquareā.
The surface will not magically appear when moving the points to coplanar, you need to create the face once they are coplanar. Simply tracing one edge will form a face if the bounding edges are coplanar.
As you see here I align the point with the origin making it planar with the rest but no face forms, a simple edge redrawn and the face forms.
Another possible solution - an extension set called āArchitect Toolsā, which has a āProject To Planeā function.
Letās say you have a situation like this:
Where 1 of the objects (green) is ever so slightly off-axis:
You pick a face to project to, and then pick edges to project:
Go all around, and it drops all the edges onto the new face:
Now pick up the resulting shape and you have it perfectly coplanar.
Thereās also Julia @eneroth3ās excellent āFlatten To Calculated Planeā, which averages out the positions of all vertices and moves them all to that average position, but I canāt demonstrate it because itās conflicting with one of my recently installed extensions and everything just disappears.
Also, FTCP sometimes breaks things, I guess because itās dragging the entire geometry, so results may vary.
The Architect Tools Project function creates brand-new lines on a fresh surface, so it takes a little longer but itās less damaging. But only suitable for relatively simple shapes.
Try them both & see which works best for you.
On behalf of all the countries using metric measurements can I please appeal to the US users to stop using imperial. What does 5/16" even mean??? isnāt it easier just to use decimals. Or even better integers!! isnāt saying ā8mmā better than ā5/16"ā This post has been a long time coming. From Melbourne Australia 
Good suggestions, but if you look at OPs post history you will see that he is still very very very slowly learning the absolute basics of the basics. Letās not make it more difficult by introducing Plugins.
I created a thread on just that topic here:
Again, people outside the US may need a VPN to view the video - it seems to vary.
That is brilliant 
We grew up using feet & inches so Iām happy using either, and it only takes 3 inches to keep my wife happy.
She isnāt fussy if itās Visa, Mastercard or Amex.
I would recommend Enerothās āFlatten to Planeā tool:
Set the axis so youāre looking down on the area you want to be a surface, then select the entities and flatten them to that.
Realistically helping the OP understand the fundamentals of sketchup geometry is more appropriate than offering more extensions. The other off topic posts are not helping the OP.
This 
On one hand, thereās understanding fundamentals. On the other hand:
1.) Solving the problem and then learning from the end result is also a factor.
2.) Avoiding wasting time & getting aggravated.
3.) Massive perspective change - once you start using extensions, you realize just how much you can do with them, that you could not (or at least it would take Godlike skill level and Buddhalike patience) do with native tools.
For example:
I WISH someone told me early on about CLF Shape Bender so I could map out shapes and then twist them into a curve.
I WISH someone told me early on about @thomthom and @eneroth3 collections, which just do so many things that itās not possible to describe here.
I WISH someone told me early on about ColorMaker so I wouldnāt have to manually map Pantone and RAL colors to Sketchup materials.
I WISH someone told me early on about @mariochaās Sketch-Int for doors and windows.
Now, when I have a complicated task, I donāt kill my nerves trying to figure out how to do it with the fundamentals - I find the EASY and EXACT way to do it with the right plugin.
