PLOT AREA (Filled Polygon) ☆

`PLOT AREA: x1, ,y1 ; x2 ,y2 ; ……; xn ,yn
` draws a filled polygon of which vertices are (x1 ,y1),(x2 ,y2),……,(xn ,yn) and (x1 , y1）.

`SET AREA COLOR numeric_expression
` specifies the filling color
The defalut area color is 1.
`ASK AREA COLOR Numeric_Variable
` assigns the current area color.
[Note]
A point is defined to be internal if any ray beginning that point crosses the boundary an odd number of times.

Enhancements to the Standard
`SET AREA STYLE string_expression
` The value of the string_expression must be one of followngs.
"HOLLOW", "SOLID", "HATCH"
`SET AREA STYLE INDEX numeric_expression
` assigns the hatch pattern when area style "HATCH" specifed. Area styles are
1: Horizontal 2：Vertical　3:Slanted(135°)　4:slanted(45°)　5:cross　6:slanted cross
[Note]
Hatch patterns are defined on the physical coordinates.
On this version, if a transformation such as the polygon crosses a line at infinity is assigned, the area style shall be ignored.
`ASK AREA STYLE String_variable
` assigns the current area style.
`ASK AREA STYLE INDEX Numeric_expression
` assigns the current area style index.