## Monday, August 9, 2010

### Grid Tutorials Chapter 1 - Modelling Basics - Part 1

It's time for the first tutorial here on 3D Grid. This first chapter is mostly for those amongst you who are new to modelling and 3D applications and need some quick information. In this first chapter we will talk about the basics of the modelling process.
In part 1 we will discuss about a very important part of 3D modelling - two dimensional (2D) operations with geometric shapes.

Chapter 1 - Modelling Basics
Part 1 - The two important dimensions

Before starting to create three dimensional objects, you must first learn how to manipulate standard two dimensional shapes and preform operations with them.

In geometry the point is the core of any geometrical shape, be it a square, a triangle or a circle. While the point has no actual dimensions (like length), we can measure the distance between two points. In 3D modelling, the point is often called a vertex (vertices pl.).

If two vertices are connected to each other, a line (edge) is created.
Three connected vertices form a triangle (has three edges). Four connected vertices form a quadrilateral (has four edges).Including the triangle, the shapes that contain more and more edges are called polygons.

When talking about modelling, you should know that most shapes or objects you see generated are usually made out of more polygons. But we will talk more about this in part 2.

As you can see in the picture above, the triangle and the square are the only ones who have a surface. The surfaces (meshes) will become more important as we move on with this tutorial.

Of course, the 3D applications allow us to manipulate these two dimensional entities and shapes. Even if we are talking just about vertices, edges or meshes, there is always something we can do to change their size, shape or orientation.

The first important operation we can do with vertices and edges is the translation. The translation basically means that you can move a vertex , edge or mesh on any axis you want. Below, you will see some examples of translations.

The red vertices represent the ones that are not selected, while the yellow ones are the vertices that are selected.
In the first example, if we select the two yellow vertices and drag them to the right, we can see them moving in the specified direction. Also notice that the edges that connect them to the other vertices is also changing length.
Right after that, if we move the two selected vertices downwards, we can see that the translation also affects the other two edges which, until now, remained still.

The second example shows how the translation of a single vertex works. The yellow vertex moves downwards and slightly to the left. This causes the edges connecting to it to also change their orientation. Lastly, the bottom vertex is selected and dragged up and to the right. Notice the changes that occur this time.

Scaling is another key function of any 3D application. With it's help you can change the size of an edge, mesh or even an entire object. When talking about three dimensional objects, the user can scale them differently on any of the three axis, depending on the result he wants to achieve.

Rotating an edge, mesh or even an object has it's uses too. Usually what happens is that the center of that edge, mesh or object is rotated around a user-defined axis. Now only that, but you can also rotate these things around other objects or surfaces as well.

That was pretty easy, huh? :)
Now it's time to get to something more serious, which is the extrusion.
Just like before, this operation can be used on vertices, edges and meshes. Below you can see the example of two extrusion operations.

This example shows how the extrusion of one edge works. The green edge is the selected one. The extrusion's direction is, by default, dependent on the normals of that edge or mesh. But the user can manipulate it in any direction he wants afterwards.
Alternatively, selecting the two vertices at each end of the edge would have had similar results, the only difference being that only those vertices would have been extruded, leaving the edge they once formed in place.

This concludes the first part of this chapter. Even if we are talking about 3D environments, you will be surprised how many times you will have to use the two dimensional view and have to work with 2D objects.

See you in part 2, where we will actually start working with 3D objects, using many of the things learned in part 1.