Use ST_RayIntersection to batch calculate intersections between rays and sfmesh objects - PolarDB

Calculates the intersections between a set of rays and an sfmesh object in a single call.

Syntax

geometry ST_RayIntersection(sfmesh sfmesh, geometry mpoint, geometry direction);

Parameters

Parameter	Type	Description
`sfmesh`	`sfmesh`	The sfmesh model object.
`mpoint`	`MULTIPOINT`	The endpoint of the ray.
`direction`	`POINT`	The shared direction of all rays. All rays in the batch travel in this direction.

Return value

Returns a MULTIPOINT geometry representing the intersections of sfmesh objects and rays.

If no intersection exists, EMPTY is returned.

Usage notes

mpoint specifies the endpoint of the ray and is of the MULTIPOINT type.
direction specifies the direction of the ray and is of the POINT type.
All rays share a single direction, specified by direction. To calculate intersections for rays in different directions, call ST_RayIntersection separately for each direction.
The input sfmesh is typically created by casting a geometry to meshgeom (for example, 'POLYGON(...)'::geometry::meshgeom).

Examples

Rays intersecting a mesh plane

Calculate the intersections of four rays — all traveling in the direction (0, 1, 0) — against a unit-square mesh centered at the origin on the XY plane.

SELECT ST_AsText(
  ST_RayIntersection(
    'POLYGON((-1 -1 0, 1 -1 0, 1 1 0, -1 1 0, -1 -1 0))'::geometry::meshgeom,
    'MULTIPOINT(0 0 0, 0 1 0, 0 -1 0, 0 -2 0)'::geometry,
    'POINT(0 1 0)'::geometry
  )
);

Expected output:

 MULTIPOINT Z ((0 0 0),(0 1 0),(0 -1 0),(0 -1 0))