Geometry Value

FDO API

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Special Character

Language Issues

The Geometry API

Geometry Value

Geometry values are handled using a function call GeomFromText('FGF Text string'), as is typical in an SQL query.

The Autodesk extension to WKT, referred to as FGF Text, is a superset of WKT (that is, you can enter WKT as valid FGF Text strings). Dimensionality is optional. It can be XY, XYM, XYZ, or XYZM. If it is not specified, it is assumed to be XY. For more information about FGF Text, see FGF Text.

NoteExtra ordinates are ignored, rather than generating an error during FGF text parsing. For example, in the string “POINT (10 11 12)”, the ‘12’ is ignored because the dimensionality is assumed to be XY.

The following is the grammar definition for FGF Text:

<FGF Text> ::= POINT <Dimensionality> <PointEntity>

| LINESTRING <Dimensionality> <LineString>

| POLYGON <Dimensionality> <Polygon>

| CURVESTRING <Dimensionality> <CurveString>

| CURVEPOLYGON <Dimensionality> <CurvePolygon>

| MULTIPOINT <Dimensionality> <MultiPoint>

| MULTILINESTRING <Dimensionality> <MultiLineString>

| MULTIPOLYGON <Dimensionality> <MultiPolygon>

| MULTICURVESTRING <Dimensionality> <MultiCurveString>

| MULTICURVEPOLYGON <Dimensionality> <MultiCurvePolygon>

| GEOMETRYCOLLECTION <GeometryCollection>

<PointEntity> ::= '(' <Point> ')'

<LineString> ::= '(' <PointCollection> ')'

<Polygon> ::= '(' <LineStringCollection> ')'

<MultiPoint> ::= '(' <PointCollection> ')'

<MultiLineString> ::= '(' <LineStringCollection> ')'

<MultiPolygon> ::= '(' <PolygonCollection> ')'

<GeometryCollection : '(' <FGF Collection Text> ')'

<CurveString> ::= '(' <Point> '(' <CurveSegmentCollection> ')' ')'

<CurvePolygon> ::= '(' <CurveStringCollection> ')'

<MultiCurveString> ::= '(' <CurveStringCollection> ')'

<MultiCurvePolygon> ::= '(' <CurvePolygonCollection> ')'

<Dimensionality> ::= // default to XY

| XY

| XYZ

| XYM

| XYZM

<Point> ::= DOUBLE DOUBLE

| DOUBLE DOUBLE DOUBLE

| DOUBLE DOUBLE DOUBLE DOUBLE

| <PointCollection ',' <Point>

| <LineStringCollection> ',' <LineString>

| <PolygonCollection> ',' <Polygon>

| <FGF Collection Text> ',' <FGF Text>

<CurveSegment> ::= CIRCULARARCSEGMENT '(' <Point> ',' <Point> ')'

| LINESTRINGSEGMENT '(' <PointCollection> ')'

| <CurveSegmentCollection> ',' <CurveSegment>

| <CurveStringCollection> ',' <CurveString>

| <CurvePolygonCollection> ',' <CurvePolygon>

The only other token type is DOUBLE, representing a double precision floating point values. Integer (non-decimal point) input is converted to DOUBLE in the lexical analyzer.

Examples of the Autodesk extensions include:

POINT XY (10 11) // equivalent to POINT (10 11)

POINT XYZ (10 11 12)

POINT XYM (10 11 1.2)

POINT XYZM (10 11 12 1.2)

GEOMETRYCOLLECTION (POINT xyz (10 11 12),POINT XYM (30 20 1.8), LINESTRING XYZM(1 2 3 4, 3 5 15, 3 20 20))

CURVESTRING (0 0 (LINESTRINGSEGMENT (10 10, 20 20, 30 40))))

CURVESTRING (0 0 (CIRCULARARCSEGMENT (11 11, 12 12), LINESTRINGSEGMENT (10 10, 20 20, 30 40)))

CURVESTRING (0 0 (ARC (11 11, 12 12), LINESTRINGSEGMENT (10 10, 20 20, 30 40)))

CURVESTRING XYZ (0 0 0 (LINESTRINGSEGMENT (10 10 1, 20 20 1, 30 40 1)))

MULTICURVESTRING ((0 0 (LINESTRINGSEGMENT (10 10, 20 20, 30 40))),(0 0 (ARC (11 11, 12 12), LINESTRINGSEGMENT (10 10, 20 20, 30 40))))

CURVEPOLYGON ((0 0 (LINESTRINGSEGMENT (10 10, 10 20, 20 20), ARC (20 15, 10 10))), (0 0 (ARC (11 11, 12 12), LINESTRINGSEGMENT (10 10, 20 20, 40 40, 90 90))))

MULTICURVEPOLYGON (((0 0 (LINESTRINGSEGMENT (10 10, 10 20, 20 20), ARC (20 15, 10 10))), (0 0 (ARC (11 11, 12 12), LINESTRINGSEGMENT (10 10, 20 20, 40 40, 90 90)))),((0 0 (LINESTRINGSEGMENT (10 10, 10 20, 20 20), ARC (20 15, 10 10))), (0 0 (ARC (11 11, 12 12), LINESTRINGSEGMENT (10 10, 20 20, 40 40, 90 90)))))

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