tree: implement casts between box2d and geometry

[otan]

Release note (sql change): Implement the ability to cast between box2d
and geometry types.

[cockroach-teamcity]

This change is 

[rytaft]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @sumeerbhola)

[sumeerbhola]

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @otan)

---

pkg/sql/logictest/testdata/logic_test/geospatial_bbox, line 152 at r1 (raw file):

NULL
POINT (-1 -1)
LINESTRING (-1 -2, 4 6)

I tried this in Postgres after writing my other comment and got

POINT(-1 -1)
 POLYGON((-1 -2,-1 6,4 6,4 -2,-1 -2))

---

pkg/sql/sem/tree/casts.go, line 817 at r1 (raw file):

			} else {
				g, err = geo.NewGeometryFromGeomT(
					geom.NewLineStringFlat(geom.XY, []float64{d.LoX, d.LoY, d.HiX, d.HiY}),

surprising that Box2D turns into a LineString and not a Polygon.

[otan]

---

pkg/sql/logictest/testdata/logic_test/geospatial_bbox, line 152 at r1 (raw file):

Previously, sumeerbhola wrote…

I tried this in Postgres after writing my other comment and got

POINT(-1 -1)
 POLYGON((-1 -2,-1 6,4 6,4 -2,-1 -2))

My mistake, every time I tried I go LineStrings but looks like it was because I did vertical / horizontal lines. good catch

[sumeerbhola]

Reviewed 4 of 4 files at r2.
Reviewable status: complete! 1 of 0 LGTMs obtained (and 1 stale) (waiting on @otan and @sumeerbhola)

---

pkg/geo/bbox.go, line 204 at r2 (raw file):

			b.HiX, b.HiY,
			b.HiX, b.LoY,
			b.LoX, b.LoY,

should we orient this CCW to start with, since we'll need to change the orientation later in code.

[otan]

---

pkg/geo/bbox.go, line 204 at r2 (raw file):

Previously, sumeerbhola wrote…

should we orient this CCW to start with, since we'll need to change the orientation later in code.

this is how PostGIS explicitly specified they'd do it :(

[otan]

bors r=rytaft,sumeerbhola

[craig]

Build succeeded:

• Compile Build (Cockroach)