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Tag: 0.2
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cl-ewkb is a geospatial library, based on cl-wkb, that implements the OGC Well-Known Binary geographic geometry data model with PostGIS 3d, 4d extensions, and provides WKB and EWKB encoding and decoding functionality. cl-wkb author is J.P. Larocue.
Depends on:
ieee-floats
flexi-streams
PostGIS extension WKB described in postgis-1.5/doc/ZMSgeoms.txt
All extensions are supported: 3dz, 3dm, 4d, embedded SRID.
Exported structs
point-primitive x y
pointz-primitive x y z
pointm-primitive x y m
pointzm-primitive x y z m
point-primtive structs contain coordinates (2d, 3d, 4d)
linear-ring points-primitive
linear-ring struct contains array of point-primitive
geometry type srid
geometry parent struct for other types and also contains "GEOMETRYCOLLECTION"
point type srid point-primitive
line-string type srid points-primitive
polygon type srid linear-rings
multi-point type srid points
multi-line-string type srid line-strings
multi-polygon type srid polygons
geometry-collection type srid geometries
Exported functions
(decode octets)
Decode from wkb sequence
(decode-from stream)
Decode from wkb stream
Functions for encoding:
(encode object endianness)
Encode object to vector
(encode-to object stream endianness)
Encode object to stream with endianness
Example:
Getting data from postgresql and decode it:
(decode (caar (query (:select (:ST_AsEWKB "SRID=4326;LINESTRING(0 0 1 2, 1 1 2 3, 2 2 3 4)")))))
Result:
#(CL-EWKB::GISGEOMETRY 3758096386 4326
#(CL-EWKB::LINEAR-RING
#(#(CL-EWKB::POINT-PRIMITIVE 0.0d0 0.0d0 CL-EWKB::POINTZ-PRIMITIVE 1.0d0
CL-EWKB::POINTZM-PRIMITIVE 2.0d0)
#(CL-EWKB::POINT-PRIMITIVE 1.0d0 1.0d0 CL-EWKB::POINTZ-PRIMITIVE 2.0d0
CL-EWKB::POINTZM-PRIMITIVE 3.0d0)
#(CL-EWKB::POINT-PRIMITIVE 2.0d0 2.0d0 CL-EWKB::POINTZ-PRIMITIVE 3.0d0
CL-EWKB::POINTZM-PRIMITIVE 4.0d0)))
CL-EWKB::LINESTRING)
Drawing data with opengl (using cl-opengl):
Draw pointXX-primitive
(defun draw-point-primitive (point)
(cond
((point-primitive-p point)
(gl:vertex
(point-primitive-x point)
(point-primitive-y point)))
((pointz-primitive-p point)
(gl:vertex
(point-primitive-x point)
(point-primitive-y point)
(pointz-primitive-z point)))
((pointm-primitive-p point)
(gl:vertex
(point-primitive-x point)
(point-primitive-y point)
0.0
(pointm-primitive-m point)))
((pointzm-primitive-p point)
(gl:vertex
(point-primitive-x point)
(point-primitive-y point)
(pointz-primitive-z point)
(pointzm-primitive-m point)))))
Drawing objects
(defun draw-point (point)
(gl:with-primitives :points
(draw-point-primitive (point-primitive point))))
(defun draw-points (line-string)
(gl:with-primitives :line-strip
(map 'nil (lambda (point) (draw-point-primitive point))
(line-string-points-primitive line-string))))
General drawing function
(defun draw-gisobject (object)
(cond
((point-p object) (draw-point object))
((line-string-p object) (draw-points object))))
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