Programmer Guide/Command Reference/EVAL/pgxgrid

Usage:

XG := pgXGrid( {pg_stream}PS, {number}IPG, {vector}X, {vector}Y )

Description:

Compute x grid inside polygon (vertical grid lines).

Result:

A matrix (N+1) x 7, N = number of vertical grid lines

row 0: general grid information

XG[0,0]=ixmin minimum x-index

XG[0,1]=ixmax maximum x-index

XG[0,2]=iymin minimum y-index

XG[0,3]=iymax maximum y-index

XG[0,4]=ngrid number of grid points inside polygon

XG[0,5]=clen abs. length of centerline

XG[0,6]=iclen rel. length of centerline

for each verical grid line i (=1..N) the following information is stored:

XG[i,0]=ix x index

XG[i,1]=iy the index of the first y point inside

XG[i,2]=ny the number of y points inside

XG[i,3]=y0 the y value of the enter-point

XG[i,4]=y1 the y value of the leave-point

XG[i,5]=cofs abs. length of centerline from begin to grid line i

XG[i,6]=icofs rel. length of centerline from begin to grid line i

Notes:

The function fails if a vertical gridline intersects the polygon more than twice.