Programmer Guide/Command Reference/EVAL/pgiline

Usage:

IS := pgILine( {pg_stream}XS, {number}IX, {number}X1, {number}Y1, {number}X2, number{Y2} )

Description:

Detect intersections of a simple-polygon with a straight line.

Parameters:

XS

The polygon stream containing the simple polygon, or point list describing the simple polygon.

IX

The index of the polygon describing the simple polygon.

X1, Y1

The x/y coordinate of the first point in the line.

X2, Y2

The x/y coordinate of the last point in the line.

Result:

Detect intersections of the line <X1,Y1>..<X2,Y2> and the polygon XS[IX].

The result IS is an "N x 3" matrix:

row 0: col0,col1 x and y of start-point

col2 0 if start-point outside and 1 if start-point inside the polygon

...

row i: col0,col1 x and y of intersection point i (i = 1 .. N-2)

col2 0 if the line leaves and 1 if the line enters the polygon

...

row N-1: col0,col1 x and y of end-point

col2 0 if end-point outside and 1 if end-point inside the polygon