Mesh, Geometry, Surface and Brep

Replies to This Discussion

Permalink Reply by David Rutten on September 16, 2015 at 12:16pm

A mesh is a collection of triangles and quadrilaterals. It is defined internally as a list of vertices (points) and faces (each face connects either three or four vertices). Meshes also support per vertex normals and colours, as well as a host of other properties.

A surface is, well, a surface. It consists of a single smooth area but may have custom edges. If a surface is just a (deformed) rectangle and it has no custom edges, it is called an 'untrimmed' surface. Surfaces with custom edges or holes punched into it is called a 'trimmed' surface.

A brep is one or more surfaces joined together. If a brep only contains a single face, then it is the same thing as a surface. For surfaces to be joined together into a brep, they need to share some of their edges.

Geometry refers to all types of geometry supported by core Grasshopper, this includes meshes, surfaces, and breps, but it also includes boxes, curves, lines, circles, points, etc.

It is possible to convert breps and surfaces into meshes, it is sometimes possible to convert a mesh back into a surface, but even if it is possible, it's difficult.

Permalink Reply by Chen Siran Maxie on September 16, 2015 at 7:37pm

Thank you very much.

I am clearer now, that really helps!