PolarDB:ST_ZupToYup

Syntax

sfmesh ST_ZupToYup(sfmesh mesh);

Parameters

Return value

An sfmesh object with its coordinate system converted from Z-up to Y-up.

Description

In some scenarios in which a Z-up coordinate system is used, the Y-up orientation is required. In these scenarios, you can use the ST_ZupToYup function to convert the coordinate system.

You can also call ST_Affine to perform the following matrix transformation to convert the coordinate system:

1.0,  0,    0,    0,
0,    0,    -1.0, 0,
0,    1.0,  0,    0

This applies the coordinate mapping: x' = x, y' = -z, z' = y.

Example

Convert a mesh from a Z-up source to Y-up orientation:

SELECT ST_AsText(
  ST_ZupToYup(
    ST_MeshFromText(
      '{"version" : 1, "root" : 0, "meshgeoms" : ["MESHGEOM(PATCH(INDEXSURFACE Z (VERTEX(0 0 2,0 10 3,10 10 1,10 0 1),INDEX((0,1,2),(1,2,3)))))"], "primitives" : [{"meshgeom" : 0}], "nodes" : [{"primitive" : 0}]}'
    )
  )
);

Result: The function adds a "matrix" field to the node, encoding the Y-up transformation:

{"version" : 1, "root" : 0, "meshgeoms" : ["MESHGEOM(PATCH(INDEXSURFACE Z (VERTEX(0 0 2,0 10 3,10 10 1,10 0 1),INDEX((0,1,2),(1,2,3)))))"], "primitives" : [{"meshgeom" : 0}], "nodes" : [{"primitive" : 0,"matrix" : [1,0,0,1,0,0,0,0,-1,0,0,0,0,0,0,1]}]}

See also

• ST_Affine — Apply an arbitrary affine transformation matrix to an sfmesh object.