Journey Into 3D #4

Ok now that you know your modelling tools, let's get a bit deeper (and longer explanation) on Polygonal modelling.


First, the Mesh
A mesh is a general term used to describe piece of geometry in 3D. It is made of many polygons and other sub-objects.

[all images] the red part are selected sub-objects. click for large view


The mighty Polygon
This is the basic piece of element to form a shape. It is also call a 'face' on a mesh. Most basic polygon is 3-sided - a triangular or 'tri' in short 3D jargon. Usually a quad (4-sided) mesh is used most of the time. A polygon is always one-sided. Meaning it only have surface on one side and it is zero-thickness. So to form a sheet of thin mat for instance, you need to create the side polygon as well. Though most of the time you don't really need thickness.


Vertex or Vertices (plural)
In a polygon mesh, you got vertices that made up the basic structure. Think of the join-the-dot game. To create tri-polygon you need 3 dots connected with Edges to form the triangle.


Edge
An edge is a space between 2 vertices. This is also forms Edgeloop which basically mean a continuous ring of edges (will explain later).

That was the basic component of a mesh. So, to make a box you need 6 polygons, 8 vertices, and 12 edges. Got it? OK good. Uhmm what else i want to talk about? Ahh modelling tools...

With polygonal modelling, you get to Cut, Split, Divide, Extrude, Bevel, etc. Remember when I said poly-modelling is like sculpting? I mean it. For example, to build a head, You create a basic geometry - a box or a sphere. Ohh btw, poly-modelling is also called box-modelling. Then you move/rotate/scale the sub-component. But moving alone is not enough. You need to cut or add polygons, say to make a nose. I'd use Extrude on polygons to raise a new set of faces to form the basic nose. To make the nostrils, I'd divide the single polygon, then inset the two faces to form new inner faces. I'd then extrude this new faces up to make a hole.


The start of a nose. Really.


The nose in it's polygonal glory


Subdivision added. I'm not a nose expert, but i think that nose is passable and kinda qute too :)

This process goes on and on - cutting, moving, extruding, until you ge the basic shape up. This might sound tedious but it is really fun actually! You'd spend hours if not days pushing verts (jargon for vertices). Then apply subdivision or meshsmoothing, you'd see your coarse model turn into something smooth, curvy and yummy :). This is also why poly-modelling is great for organic model which need that handcraft touch.

Until next post, have fun pushing verts!