Surfaces - Polygon (multisided shape)

The most general surface

When creating a new surface, this is the default type.

Creating a new surface

After pressing the new surface button, you need to sequentially select points on the drawing. This creates a multisided shape with any number of straight or curved segments. You don't need to close the line; the program will automatically do this.

Selecting points

Several important points to consider when selecting points!

Traversal

The traversal of the corner points should be clockwise for the surface to face the light.

• This means that the 3rd point must be to the right of the line connecting the 1st and 2nd points. This way, the surface will appear lighter the more it faces the light.
  
  
• If the traversal is counterclockwise, it will be the opposite.
  
  
• Of course, every surface can be viewed from two sides; from one side, the points are clockwise, and from the other side, they are counterclockwise.
  
  
• The traversal determines which side of the surface reacts correctly to the light.
  
  
• The surface behaves like a planar sheet, not like a paper sheet. If one side of the paper is lit, the other side is shadowed. Our surface will always be equally light or dark on both sides.
  
  
  • If you want to create a paper-like sheet, you need to create two identical surfaces at a small distance from each other, and both surfaces should have clockwise traversal when viewed from their respective sides.
    
    

  If, for any reason, clockwise traversal is not feasible, this icon pair allows the system to be reversed.

Grain direction

The texture grain direction on the surface will be parallel to the line connecting the 1st and 2nd points. This is true if the grain direction on the texture file is vertical. All textures in the program are set this way.

Planes

A polygon is a planar shape, but it can slightly bend into space.

• The program automatically subdivides all surfaces into triangles, but we cannot intervene in this process.
  
  
• In the example, a corner of a planar quadrilateral has been moved into space.
  
  
• A quadrilateral can be subdivided into 2 triangles in two ways. The program cannot be instructed which method to use. The point is to keep the polygon within the plane as much as possible to avoid unexpected results.
  
  
• For more complex spatial shapes, there is a separate type: the general curved surface.
  
  
  
  

Parameters

Transparency

The transparency of the surface can be set to a value between 0 and 255. Note that if you use a color with transparency for this surface, the two values will add up.

Repetition distance

This option allows the polygon (only the polygon) to be repeated at given distances. This only applies to the width value, so as you increase the bounding size of your object in width, more instances of the given polygon will appear.

 
 

Polygon clipping

You can cut out a rectangular area from any polygon.

• Two consecutive surfaces are required for this:
  
  
  • The first is any polygon, and the second is a regular rectangle with edges parallel to the coordinate axes, with points selected in the mandatory order shown in the figure.
    
    
  • The second surface should be set to the polygon clipping type.
    
    
  • The resulting polygon's color and parameters should also be set on the 2nd surface.
    
    
• This is mainly used when a fixed pattern shows a part depending on the front size (e.g., wavy front).
  
  
  
  

Hole clipping

You can cut out any other polygon from a given polygon.

Again, two surfaces are needed; the first is clipped by the second. The resulting polygon's color and parameters should also be set on the 2nd surface.

Inner area shading

Similar to hole clipping, but instead of a hole, you get a shaded area.

The resulting polygon's color and parameters should also be set on the 2nd surface, including the shading value. The base surface cannot be shaded separately in this case.

Keywords: #polygon #multisided shape