Example 25

 

The main purpose of this example is to show you one particular feature of the triangulation option used in both the Polygon A and Polygon B types. The triangulation feature only applies to the base and top sides of the polygon, or the front and back sides of it, if the polygon is placed in a horizontal position. If you are making a big terminal or similar building having a large surface you will then need to use a texture to make the roof part of it. It is quite obvious that using a roof texture several times will result in greater efficiency and produce a nicer and more detailed roof than using it only once.
This example will show how to repeat a texture when making such object.

This shows a top view of the terminal. The same texture surface is
used 5 times to make the roof.

 

This is the layout of the top of the terminal. As you can see it will not give you the desired effect.

To repeat a texture you will need to add more points and/or sides to the polygon.

The final view will have a layout as shown here.

You can see that the roof has been divided into sections. Section 1-2-3-12 will make a complete section and 5-6-7-8 will make another section.

The added points must be properly aligned or you'll get a distorted view in the scenery. For example points 10 and 5 have the same X coordinates value as have 11 and 4.

This shows the roof divided into 5 sections. If you fold the picture along the red dots you will eventually get only one polygon. This is exactly what we need to do so each section will have the same surface texture.

 

This shows 3 sections of the roof separated by red dotted lines. These sections are described as:
1-2-3-12
12-3-4-11 ---> this texture is horizontally flipped
11-4-5-10
At first this seems to be a little difficult but, once you place the first 4 points, you will realize that adding the remaining points is very easy.

The first points to place will be 1-2-3 and 12. Once they are placed in the right position you'll only need to place 2 points for each additional section.

If you make the first fold you'll see that point 11 will be placed at the same position as 1 and point 4 will be placed at the same position as 2.
After a second fold you'll see that point 10 will be placed at the same position as 12 and point 5 will be placed at the same position as 3.

 

The texture used for the roof is NOVA050.BMP

Once all sections are made you will get a graphic, like the one shown here, where only 4 small blue delimiter boxes are visible.

Once this is done we can then proceed with the triangulation to tie each section of the texture to the points.

Sets can be made in any order provided you place the 3 points of the set in clockwise order. This clockwise order is a must when the polygon is placed in a horizontal position but is not needed if the polygon is placed in a vertical position.

For example - Set1 is made of points 1-2-3, but 2-3-1 and 3-1-2 will give the same results.