Nome
CG_3DDifference — Perform 3D difference
Sinossi
geometry CG_3DDifference(geometry geom1, geometry geom2);
Descrizione
Returns that part of geom1 that is not part of geom2.
Availability: 3.5.0
Questo metodo richiede il backend SFCGAL.
Questo metodo implementa la specifica SQL/MM. SQL-MM IEC 13249-3: 5.1
Questa funzione supporta il 3d e non distrugge gli z-index.
Questa funzione supporta le Polyhedral Surface.
Questa funzione supporta i Triangoli e le Triangulated Irregular Network Surfaces (TIN).
Esempi
Subtract a smaller tetrahedral solid and render the two inputs and the actual remaining solid separately.
Code
WITH data AS (
SELECT CG_MakeSolid('POLYHEDRALSURFACE Z (
((0 0 0,0 4 0,4 0 0,0 0 0)),
((0 0 0,4 0 0,0 0 4,0 0 0)),
((0 0 0,0 0 4,0 4 0,0 0 0)),
((4 0 0,0 4 0,0 0 4,4 0 0))
)'::geometry) AS outer_solid
), solids AS (
SELECT outer_solid,
ST_Scale(outer_solid, 0.5, 0.5, 0.5) AS inner_solid
FROM data
)
SELECT outer_solid AS input_outer,
inner_solid AS input_inner,
CG_3DDifference(outer_solid, inner_solid) AS difference
FROM solids;
Output
POLYHEDRALSURFACE Z (((0 0 0,0 4 0,4 0 0,0 0 0)),((0 0 0,4 0 0,0 0 4,0 0 0)),((0 0 0,0 0 4,0 4 0,0 0 0)),((4 0 0,0 4 0,0 0 4,4 0 0))) | POLYHEDRALSURFACE Z (((0 0 0,0 2 0,2 0 0,0 0 0)),((0 0 0,2 0 0,0 0 2,0 0 0)),((0 0 0,0 0 2,0 2 0,0 0 0)),((2 0 0,0 2 0,0 0 2,2 0 0))) | POLYHEDRALSURFACE Z (((0 2 0,4 0 0,2 0 0,0 2 0)),((0 0 2,2 0 0,0 0 4,0 0 2)),((0 0 2,0 4 0,0 2 0,0 0 2)),((4 0 0,0 4 0,0 0 4,4 0 0)),((4 0 0,0 2 0,0 4 0,4 0 0)),((2 0 0,4 0 0,0 0 4,2 0 0)),((0 4 0,0 0 2,0 0 4,0 4 0)),((0 0 2,0 2 0,2 0 0,0 0 2)))
Figure