As it has been covered during the previous classes, it is important if not necessary to have the 2D drawing in order to start the 3D modeling. In this case, we took as a base/guide a section, not an entire section but just a half of it since the model is symmetrical.

First of all, we start by drawing a RECTANGLE in the auxiliar layer to define the limits of our section, we divide the rectangle into multiple zones using XLINE to help us draw the section. Then, using the command POLYLINE we connect multiple intersection points to create it. Since it's still quite rigid, we use another command called FILLET that allow us to obtain circular edges by connect two lines and setting a radius. After we get the final curved line we use OFFSET to give it a thickness.



Secondly, we call for the BPOLY command that will help us create a continuous limit of the section. One for the concrete structure and the other one for the glass openings. After doing that, it is possible to create the 3D model using a very interesting command called Revolve. How does it work? it allows us to rotate while copying a set of surfaces around a chosen axis. We define a number of planes which is 36 using ISOLINES, SURFTAB1 and SURFTAB22. It is important to know that the more planes we use the smoother and better the revolved volume gets.

It's common knowledge that there are plenty of softwares and applications dedicated to 3D modeling: some of them are easy to use, others require a good knowledge of geometry principles. However, the most famous of them all is AutoCAD.

AutoCAD is a computer-aided design (CAD) program used for 2-D and 3-D design and drafting. AutoCAD is developed and marketed by Autodesk Inc. and was one of the first CAD programs that could be executed on personal computers.

Over the past few years, I used the program to create 2D layouts and I thought it was quasi-impossible for me to create 3D models on the same platform but it turns out that it is not as hard as it might seem and with a little bit of practice and knowledge of the basics of the software, it could be possible to design anything from basic shapes which is the theme of the second class to complex architectural forms and structures.

Before starting the modeling of any object, it is necessary to understand it not only three-dimensionally but also how it is projected onto 2D plans along with sections because every model emerges from 2D layouts. The following examples show us the basics of the modeling part of the object:

Tetrahedron: 

Starting with a circle (the CIRCLE command, and then we enter the coordinates of the central point and the lentgh of the radius) drawn on the XY plan to serve to purpose of a guide to us to indicate the 3 points that will allow us to draw the base of the tetrahedron. The division is made possible with the DIVIDE command and the points are connected with POLYLINE. To create the surface of the equilateral triangle we use the SHADE command and we connect the three points.