# Can't disolve edge and faces

I am very new to blender and I have a problem where I can't dissolve these two faces and I don't know why. Can someone help me ?

Link to the blender file if anyone need it : https://mega.nz/#!BxBkVA5b!Xz0vgBDgfhW32xzLA_DX5Xp-r9dFMtxl2wbwyY0Km5U

• please, at least next time, could you use blend-exchange.giantcowfilms.com service to upload .blend files, since it's the preferred way here? Thanks – m.ardito Feb 28 '17 at 11:05
• I think you can't dissolve. Because dissolve will lower the geometry, and if you do it here, the wall will overlap the windows – lemon Feb 28 '17 at 11:29

## 1 Answer

A face is a polygon. A polygon is an array of vertices.

The way it is interpreted is:

• Make a first triangular part with vertices 1, 2, 3
• Then make another one with 2, 3, 4
• Then 3, 4, 5
• Etc.

This does not allow to have holes in it except if there is only 1 hole, or in some special cases for example if the holes are triangular themselves (at least, I think, this is surely a complex topology problem...).

So, my though is that you can dissolve only if there is a path of triangles "calculable" all along this polygon. And I don't think this is the case here due to the 3 square holes. Or if you dissolve, the polygon will cover/overlap the windows.

• Alright, so right now it's the best I can achieve if I understood correctly ? – A Real Snake Feb 28 '17 at 11:53
• I think the question is "why do you need to do that ?". And yes, you cannot lower the amount of faces here. But after a look at your file, some vertices can be removed. – lemon Feb 28 '17 at 11:54
• Mainly for UVs, I like it when things are 100% clean, but I guess I will have to do with it. Thansk for the help ! – A Real Snake Feb 28 '17 at 12:05
• @ARealSnake it's most likely that you won't get everything clean when having Ngon like that, UVs don't like such distortion. Go with quads or tris if low-poly and unwrap. – Mr Zak Feb 28 '17 at 12:35
• Thanks for the info again, it will greatly help me in the future ! – A Real Snake Feb 28 '17 at 14:44