Polygon

A polygon is an object defined by a list of at least three positions, comprising a closed wire and a face. The polygon is drawn sequentially based on the order of the positions within the list.

Description	Example
Workflow of making a polygon
Representation of a polygon in the 3D Viewer
Representation of a polygon in the Attribute Table

Front and Back Surface

For each polygon, there is a front and back surface. A typical practice when modelling is to show the front surface on the exterior. By default, the front face is white while the back face is grey; however, users may customise the display colours of the surface in the 3D Viewer Settings.

See Changing the Display Colour of Front and Back Surfaces
See Common Misconceptions and Workflow Mistakes: Order of Items in Lists
See Common Misconceptions and Workflow Mistakes: Direction of Normal

Normal

A normal is a vector that is perpendicular to a polygon or pattern.

Calculating the Normal

Function calc.Normal is used in calculating normals of each polygon

Example: Extrude a Polygon in the Direction of its Normal

1. Identify the polygon surface for extrusion.
2. Use calc.Normal to calculate the normal. Set the length of extrusion in the scale argument box of the function.
3. When extruding, key in the normal variable distance into the argument box.

See Common Bugs and Misconceptions: Direction of Normal