ResizeContour

John Edmundson — Thu, 01 Oct 2026 23:25:21 GMT

Does anyone have a simple example of using the "ResizeContour" command? It can be as small as a 10'x10' box that is made 5' larger with the command. I have been trying to understand the POLYGON OPERATIONS EXTENSION (GDL Reference Guide - page 647) without success. I wish the manual had included a simple example.

Thanks

Re: ResizeContour

rudl — Wed, 07 Oct 2026 15:56:03 GMT

Don't know that extension but
You could have your poly curve in a twodimensional array and use the following code (created with help oh chatgpt)
and later use the parameter buffer to feed the POLY2

offset the offset you want (constant edge offset)
working_profile is the input array use working_profile = your array before running the sub
profile_off is the output array
profile_off_reset array to clear profile off just in case.

"offsetpoly": profile_off = profile_off_reset FOR i = 1 TO nProfile IF i = 1 THEN ip = nProfile ELSE ip = i - 1 ENDIF IF i = nProfile THEN in = 1 ELSE in = i + 1 ENDIF ! -------------------------------------------------------- ! EDGE 1: previous -> current ! -------------------------------------------------------- dx1 = profile_working[i][1] - profile_working[ip][1] dy1 = profile_working[i][2] - profile_working[ip][2] len1 = SQR(dx1 * dx1 + dy1 * dy1) nx1 = dy1 / len1 ny1 = -dx1 / len1 ! -------------------------------------------------------- ! EDGE 2: current -> next ! -------------------------------------------------------- dx2 = profile_working[in][1] - profile_working[i][1] dy2 = profile_working[in][2] - profile_working[i][2] len2 = SQR(dx2 * dx2 + dy2 * dy2) nx2 = dy2 / len2 ny2 = -dx2 / len2 ! -------------------------------------------------------- ! POINTS ON THE TWO OFFSET LINES ! -------------------------------------------------------- x1 = profile_working[i][1] - nx1 * offset y1 = profile_working[i][2] - ny1 * offset x2 = profile_working[i][1] - nx2 * offset y2 = profile_working[i][2] - ny2 * offset ! -------------------------------------------------------- ! INTERSECTION ! -------------------------------------------------------- denom = dx1 * dy2 - dy1 * dx2 IF ABS(denom) > 0.000001 THEN t = ((x2 - x1) * dy2 - (y2 - y1) * dx2) / denom profile_off[i][1] = x1 + t * dx1 profile_off[i][2] = y1 + t * dy1 ELSE ! Parallel / 180° corner profile_off[i][1] = x1 profile_off[i][2] = y1 ENDIF NEXT i profile_working = profile_working_reset RETURN

topic Re: ResizeContour in GDL

ResizeContour

Re: ResizeContour