When modeling in 3D with polygons, it is important to construct all of your models using quads and triangles.
A triangular polygon is referred to as a tri or triangle, and is a simple three-sided polygon. It has exactly 3 vertices at its corners and 3 edges connecting those points. This is the smallest configuration required to make a polygonal face.
A square or rectangular polygon is referred to as a quad or quadrilateral polygon, and is a four-sided polygon. It has exactly 4 vertices at the corners connected by 4 edges. This is the most desired type of polygon when creating digital models, and many artists like to build their objects using nothing but quads to help make their work more appealing to customers in complex pipelines.
An N-Gon is a polygon with more than four vertices and edges. This kind of polygon is not desired by TurboSquid customers and should be avoided. Due to its geometric properties, an N-Gon can always be divided into quads, tris, or a combination of the two; so they are always easy to remove by adding connecting edges between the border vertices.
Why N-Gons Should Be Avoided
Difficulty when subdividing
- N-Gons subdivide poorly and produce unwanted topology, even on flat surfaces. While it may be quicker to model using N-Gons, it is a bad habit to get into as they disrupt the edge flow of your model, making selection of edge loops more difficult. Having N-Gons often leads to strange rendering or smoothing artifacts that are hard or impossible to eliminate. Instead of leaving N-Gons around in your model, it is better to avoid them altogether since quads and tris will always subdivide properly.
Unwanted behavior when importing and exporting
- Some applications do not handle N-Gons well or at all. Popular sculpting products like ZBrush, Mudbox and 3D Coat will bring up alert messages when an artist tries to import a model with N-Gons present, and sculpting across those surfaces will produce unwanted results. For customers, Ngons can cause major issues when trying to use your model in multiple environments and as such, need to be avoided.