Polygon type A and B

NOVA comes with two polygon types, Polygon A and Polygon B. This table shows the differences between both types:

  Polygon A Polygon B
Maximum number of points 10 20
Textures with transparency options ALL NONE
Skew and Raise options  YES NO
Raise top points YES NO

POLYGON POSITION:

This picture shows the same polygon of 8 sides in both positions
There are two additional options when making an horizontal polygon and they work the same way as in the cube.
  • Skew: You can skew the front and back sides of the polygon from right to left and/or vice versa
  • Raise Polygon:  Will raise one end of the polygon
This is an example of two polygons using the skewed option
The same polygon, but raised in the front.

 HORIZONTAL POLYGONS - IMPORTANT NOTES

When placing the polygon in horizontal position, the Y axis becomes in fact the height of the polygon. 

The lower side of the polygon will stay over the ground, so the altitude or Y axis coordinates will be 0 ( zero ).

In the left picture, if you place points 1 and 8 underneath the ground level, you will not see sides 1 and 7 that partially in the scenery.

 

Another important issue will be visibility problems. The left picture shows an example.

This problem is easily resolved by reversing the side draw in the texture panel. More information can be found here.

There is also a close relationship between the physical shape of the polygon and the textured points positions, or the polygon will be distorted or some how, with rotated points or in complete disorder.

 

TRIANGULATION

This feature only applies for the base and top sides of the polygon, or the front and back sides if the polygon is draw horizontally.

You will have to use this feature almost every time you have an  asymmetric shape.

This is one of the multiples cases you may have, the left picture represents a building with an L surface shape, and in the right you will see what happens if the if you don't use the triangulation option for polygons.
The triangulation is not other thing that divide the surface in triangles in any way and order. Then you will have to enter for each triangle, the points making part of it.

The triangulation panel will look something like this when accessed the first time.

To the left you have the polygon with the vertex numbered from 1 to 9 then from A to K if you have up to 20 sides.

To the right, you have all the required number of sets as triangles you need. Each set must  be filled with 3 numbers or points, so we will start, in any order, making the triangulation...as

126 for example....and so on. If your polygon has more than 9 sides, then you will use letters as well, as 7DA for example or any other combination.

Your screen will look at the end something like this.

Each triangle shows a different color, this color is the same as in the set box text number.

You can enter the points in any order, 123, 321,213 and 132 are all the same.

 

 

Hopefully, the polygon will display properly once the triangulation is done.
You can use the polygon also if you have a building where you have to repeat a few times the same texture, something like the left picture.

Do you need to make a triangulation here?. Well I should say it all depends on the quality of building texturing you want to have in the roof. The answer is yes an no...

If you don't use triangulation, the program will generate the points in accordance with the entries you have done.

If you want to use the triangulation, you have now some options:

Why not...you could only make 2 big triangles here, like 126 and 167, and it will work of course. The problem here is that the roof will be so stretched, that it will be very ugly. This option will be the same as not using triangulation.

The best option would be to repeat the same texture in the roof. This is something hard to try the first time, but it is worthy to try.

Well, this building looks like this, without triangulation. What I want, is to use the same roof texture 4 times, instead of one as actually it does, so texturing will be improved, if this is what we are looking for. For this exercise, I have numbered the points on the texture for a better understanding.
This is graphically the right distribution of points to be made. If you fold this picture by the dotted points, you will see that some points will be overlapped, and share the same position.
If you fold the picture, point 4 will be placed over point 2, 5 over 3 and 6 over 2.
The same will happens to the lower points, and at the end, you will get just one picture that will look like the left picture.
And finally, we will make the triangulation.
The final  version of the building. You get some important advantages using this method as,
  • Your textures can be smaller to cover the same surface, so you will use less space, and gain CPU performance or better frame rate.
  • Avoid fuzzy buildings texturing. This is more obvious if your building is very long, as a 300 meters terminal for example.

For more information, you can load the file NOVAEX03.NOV used in this example.