PRIMITIVES
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The plane, the torus, the sphere, the cylinder, the cone and of course, the most heavily abused of all the shapes in blender - the cube.
These are the 3d primitives which come with blender - or almost any 3d package for that matter.
They are the simplest way to describe these basic shapes and are used as the foundations for almost every modelling task you will ever attempt.
The problem with the primitives is that they are just that - primitive.
There is a big difference between Subdivision surface models and Polygonal models. The primitives blender provides (except the torus!) are all polygonal models.
It is difficult to use any of them in real world renders because they have impossibly sharp edges which cannot react to light the way we would expect to see in the real world. (Except the plane! The plane is perfect. Four vertices connected by four edges, filled in with a single face. I wouldn’t change a thing!)
This is a good place to start learning about subdivision surface modelling and making these objects provides significant opportunities to start thinking in terms of real world shapes before we start to tackle more complex topologies.
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The Cylinder.
Fixing the cylinder will help us to understand the basic nature of all subdivision surface models; They have a logical orientation.
In this case - a top, a cross section, a bottom and boundaries between these elements to control curvature.
The cylinder blender provides us with has two options for the top and bottom of the shape; triangles or n-gons, both of which should be avoided whenever possible in subdivision surface modelling. ​While it is not always possible, we want quads and only quads!
A correct subdivision surface cylinder reveals the composition of almost every Sub-D model. It has regions which can ultimately be connected to anything at all while retaining control of its curvature.
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The Sphere.
Blender provides two flavours of sphere: The icosphere and the UV Sphere.
The IcoSphere is made from triangles which do not work well with the subdivision surface modifier.
The UV Sphere has two mega-poles at the top and bottom which also cause problems with the Subdivision Surface Modifier because of the angles the connecting poles create.
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The usual method to create a sphere for Sub-D work is to create a Quad Sphere but the one most people use is incorrect and will cause problems.
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There are add-ons which create a version of the quad sphere but these are not correct either!
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We will look at the problem with the common quad sphere and provide a useable solution which is very commonly used in subdivision surface modelling.
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The Cube.
Delete it or not, it is an essential and heavily used starting point for almost everything.
As a subdivision surface model however, it does not work at all. The blender cube It is conceptually more akin to a very low resolution sphere than a cube!
We like things to have orientation in Sub-D modeling so that we can identify and model the top, bottom and cross section of the models. There are many cubes we can use and I will show you how to make them all and when each one is most appropriate. The one we make here is not the best one in most cases! But it is the best one to start thinking about the overall structure of subdivision surface models. I will talk about the others when we discuss corner topologies.
We need to re-think what a cube actually is to make it usable in real renders.
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The Torus.
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The torus has great topology and is suitable as a subdivision surface model!
However, blender does not allow us to change key properties of the torus, such as its resolution or its minor radius which means it is a good candidate for an upgrade!
The model we will create will be identical to the one provided by blender but we will use some techniques which allow us to edit some key properties of the torus while we are deciding where it should go and how it should look within our scene.