Monday, April 30, 2012

Blender 2.63 BMesh, Part 1

The purpose of this tutorial is to compare some pre-BMesh and post-BMesh modeling operations, to give you a flavor for why BMesh is a good thing. BMesh is a rewrite of the modeling architecture in Blender to support polygons of any number of sides. Before Blender 2.63 Blender only supported triangles (3 sided polygons) and quadrilaterals (quads) (4 sided polygons). With BMesh, Blender can create polygons with any number of sides.

We’ll start with Subdivide. Subdividing is a good place to begin looking at BMesh because subdivide actually is an edge related edit operation (you’re basically splitting edges in half). Edges correlate to sides of a polygon. Subdivide either explicitly splits an edge (if an edge is selected), or implicitly splits the edges formed by the selected vertices and/or faces. This process creates new vertices, which must belong to a face. The vertex cannot just be sitting on an edge without belonging to a face. Before Blender 2.63 (i.e., with BMesh), the face could only be 3 sided (triangle) or 4 sided (quad). With BMesh, the face can have any number of edges. This makes for a cleaner topology, making it easier to add detail to your model.