im new in blender.

I have a cube and only move the edge, one face look good but the other.....

Its a bug or im doing something wrong?



  • $\begingroup$ Faces do not work well concave like that. Instead of one face at the end, split it into two, and it will work as you expect it. $\endgroup$
    – David
    Commented Jun 24, 2017 at 23:11
  • $\begingroup$ Related: Flat quads (or, why is my mesh so funky?) $\endgroup$
    – user1853
    Commented Jun 25, 2017 at 0:07

1 Answer 1


Go into edit mode, and press A to select all the vertices. Press the spacebar and type in "Triangulate Faces," and that should fix the problem.

Blender sometimes has problems calculating bent rectangles (technically known as quads), because they can be made out of two triangles bent one out of two ways. Take this plane for example: enter image description here

It can be made of either these triangles: enter image description here

Or these triangles:

enter image description here

As you can see, both versions use the same exact vertex locations, but achieve completely different effects. However, Blender doesn't know which one to choose. In your case, Blender gets confused and decides to basically fold the weird looking face in half, instead of making it concave. By using "Triangulate Faces," you are basically asking Blender to turn each face into a specific set of triangles, so that way it doesn't get confused about the possibilities. In the end, your cube should look like this: enter image description here

I hope I helped you, and let me know if you have any questions.

Happy Blendering, Graves Broderick

  • $\begingroup$ Of course! Have fun learning Blender! $\endgroup$
    – Zacocast
    Commented Jun 24, 2017 at 22:40
  • $\begingroup$ Would you mind marking my answer as accepted and voting it up to show others it works? $\endgroup$
    – Zacocast
    Commented Jun 24, 2017 at 22:41
  • $\begingroup$ If you are just starting with blender you should start to learn about proper topology... Start by avoiding non planar geometry (read this). Also is not such a good idea to start by turning quads into trianlges... Try to create meshes with quads. Read this other link as well $\endgroup$
    – user1853
    Commented Jun 24, 2017 at 23:56

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