MODELLING CONCEPTS

Any filled face with exactly three edges connected in sequence is a triangle. Triangles are always planar.

Triangles are to be avoided.

They indicate the termination of flow around an object and can cause artefacts at render time if they are involved in any area of deformation.

 

The subdivision surface algorithm does not work well with triangles, compressing detail and compounding errors as it works.

 

For good flow to be possible through a model, there needs to be an edge (any edge) of a polygon which is connected to two others which will not be considered as exit routes for this flow (the adjacent edges). A single edge, connecting these two, will be the exit for the flow through the surface and this ‘quad’ based topology what we are looking for.

Triangles terminate the flow around edge loops and that is not what we want.

If a curved area of your geometry contains triangles there will be a pinching of light causing rendering artefacts around the area.

As with all of our concerns in subdivision surface modelling, there will be occasions where you cannot easily and efficiently avoid a triangle. These triangles are rare but they will need to be hidden in areas where they will not affect renders.