CG_Visibility — Compute a visibility polygon from a point or a segment in a polygon geometry
geometry CG_Visibility(
geometry polygon, geometry point)
;
geometry CG_Visibility(
geometry polygon, geometry pointA, geometry pointB)
;
Availability: 3.5.0 - requires SFCGAL >= 1.5.0.
Requires SFCGAL >= 1.5.0
This method needs SFCGAL backend.
This function supports 3d and will not drop the z-index.
This function supports Polyhedral surfaces.
This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).
SELECT CG_Visibility('POLYGON((23.5 23.5,23.5 173.5,173.5 173.5,173.5 23.5,23.5 23.5),(108 98,108 36,156 37,155 99,108 98),(107 157.5,107 106.5,135 107.5,133 127.5,143.5 127.5,143.5 108.5,153.5 109.5,151.5 166,107 157.5),(41 95.5,41 35,100.5 36,98.5 68,78.5 68,77.5 96.5,41 95.5),(39 150,40 104,97.5 106.5,95.5 152,39 150))'::geometry, 'POINT(91 87)'::geometry);
SELECT CG_Visibility('POLYGON((23.5 23.5,23.5 173.5,173.5 173.5,173.5 23.5,23.5 23.5),(108 98,108 36,156 37,155 99,108 98),(107 157.5,107 106.5,135 107.5,133 127.5,143.5 127.5,143.5 108.5,153.5 109.5,151.5 166,107 157.5),(41 95.5,41 35,100.5 36,98.5 68,78.5 68,77.5 96.5,41 95.5),(39 150,40 104,97.5 106.5,95.5 152,39 150))'::geometry,'POINT(78.5 68)'::geometry, 'POINT(98.5 68)'::geometry);