The Documents of Stage Hands

Dynamically Additive Geometry for Sculpting in Blender


SHWith the advent of Blender changing it’s polygon engine to include Ngons, as opposed to only supporting triangles and quadrangles (post version 2.63), a new mesh system known as Bmesh has been introduced to Blender and brought with it several new features. Besides the obvious advantages of creating polygon models faster (which are generally not intended for usage with deformations respecting topology), an addition to Blender’s sculpting toolset in the form of Dyntopo also takes advantage of the new mesh system’s versatile approach to working with polygon geometry.

BMesh Basics

In simplest terms, for an end-user, BMesh is a set of new instructions that Blender uses to display polygon geometry in the viewport. Prior to the inclusion of BMesh all polygons displayed in a 3D viewport in Blender could only be made up of a four-sided polygon (quadrangle) or a three-sided polygon (triangle). In order to construct a complex 3D model these simple “building blocks” must then be contiguously arranged to represent the shape or form of the model. ngons
Amongst the advantages of this old system with regards to triangles is that many thousands of triangles can be computed and displayed relatively quickly as much of what the math engine computes in the background is very close to what the user sees in the viewport, this in-part attributes to why so many games engines require geometry to be triangulated before run-time.

Quadrangles on the other hand have become almost synonymous with creating models that deform with respect to the edge-loops that comprise their topology. The rectangular nature of quadrangles when placed side by side make it very easy to visualize the edge-loops that need to be strategically placed on a model that will be continuously deformed, for example, during animation.

Ngons do not replace the advantages of triangles and quadrangles, but rather augment the previously existing mesh system in Blender by simplifying (and speeding up) the task of creating geometry that is not intended for continuous deformation for example a character in a still pose, an inanimate object for a background prop or various applications in architectural visualizations to name a few uses for Ngons.