Merge pull request #896 from astroidex/master

added new help files for geometry functions

resources/function_help/$geometry

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+<h3>$geometry function</h3>
+Returns the geometry of the current feature. Can be used for processing with other functions.
+
+<h4>Syntax</h4>
+<pre>$geometry</pre>
+
+<h4>Arguments</h4>
+None
+
+<h4>Example</h4>
+<pre> geomToWKT( $geometry ) &rarr; POINT(6 50)</pre>
+

resources/function_help/buffer

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+<h3>buffer function</h3>
+Returns a geometry that represents all points whose distance from this geometry is less than or equal to distance. Calculations are in the Spatial Reference System of this Geometry. 
+
+<h4>Syntax</h4>
+<pre>geomFromWKT(text)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+float    &rarr; radius of buffer
+
+<h4>Example</h4>
+<pre> buffer($geometry, 10.5 ) &rarr; returns a polygon</pre>
+

resources/function_help/centroid

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+<h3>centroid function</h3>
+Returns the geometric center of a geometry.
+
+<h4>Syntax</h4>
+<pre>centroid(geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> centroid($geometry) &rarr; returns a point geometry</pre>
+

resources/function_help/combine

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+<h3>combine function</h3>
+Returns the combination of geometry a and geometry b.
+
+<h4>Syntax</h4>
+<pre>combine( geometry a , geometry b)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> geomToWKT( combine( geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5 )' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4,  2 1 )' ))  )    &rarr; returns MULTILINESTRING((4 4, 2 1), (3 3, 4 4), (4 4, 5 5)) </pre>
+<pre> geomToWKT( combine( geomFromWKT( 'LINESTRING(3 3 , 4 4  )' ) , geomFromWKT( 'LINESTRING(3 3 , 6 6,  2 1 )' ))  )  &rarr; returns LINESTRING(3 3, 4 4, 6 6, 2 1) </pre>

resources/function_help/contains

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+<h3>contains function</h3>
+ Returns true if and only if no points of b lie in the exterior of a, and at least one point of the interior of b lies in the interior of a. 
+
+<h4>Syntax</h4>
+<pre>contains( geometry a , geometry a)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> contains( geomFromWKT( 'POLYGON((0 0 , 0 1 , 1 1 , 1 0 , 0 0 ))' ) , geomFromWKT( 'POINT( 0.5 0.5 )' ))    &rarr; returns 1</pre>
+<pre> contains( geomFromWKT( 'POLYGON((0 0 , 0 1 , 1 1 , 1 0 , 0 0 ))' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))          &rarr; returns 0</pre>

resources/function_help/convexHull

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+<h3>convexHull function</h3>
+Returns the convex hull of a geometry. It represents the minimum convex geometry that encloses all geometries within the set.
+
+<h4>Syntax</h4>
+<pre>convexHull( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre>  geomToWKT( convexHull( geomFromWKT( 'LINESTRING(3 3 , 4 4 , 4 10)' )) )   &rarr; returns POLYGON((3 3,4 10,4 4,3 3)) </pre>

resources/function_help/crosses

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+<h3>crosses function</h3>
+Returns 1 if the supplied geometries have some, but not all, interior points in common.
+
+<h4>Syntax</h4>
+<pre>crosses( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> crosses( geomFromWKT( 'LINESTRING(3 5 , 4 4 , 5 3)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))    &rarr; returns 1</pre>
+<pre> crosses( geomFromWKT( 'POINT(4 5)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))             &rarr; returns 0</pre>

resources/function_help/difference

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+<h3>difference function</h3>
+Returns a geometry that represents that part of geometry a that does not intersect with geometry a.
+
+<h4>Syntax</h4>
+<pre>difference( geometry a , geometry b)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> geomToWKT( difference( geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4)' ))  )   &rarr; returns LINESTRING(4 4, 5 5)</pre>

resources/function_help/disjoint

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+<h3>disjoint function</h3>
+Returns 1 if the Geometries do not "spatially intersect" - if they do not share any space together. 
+
+<h4>Syntax</h4>
+<pre>disjoint( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> disjoint( geomFromWKT( 'POLYGON((0 0 , 0 1 , 1 1 , 1 0 , 0 0 ))' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' )) &rarr; returns 1</pre>
+<pre> disjoint( geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ) , geomFromWKT( 'POINT(4 4)' ))                              &rarr; returns 0</pre>

resources/function_help/distance

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+<h3>distance function</h3>
+ Returns the minimum distance (based on spatial ref) between two geometries in projected units.
+
+<h4>Syntax</h4>
+<pre>distance( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> distance( geomFromWKT( 'POINT(4 4)' ) , geomFromWKT( 'POINT(4 8)' ))    &rarr; returns 4</pre>

resources/function_help/geomFromGML

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+<h3>geomFromGML function</h3>
+Returns a geometry from a GML representation of geometry
+
+<h4>Syntax</h4>
+<pre>geomFromGML(text)</pre>
+
+<h4>Arguments</h4>
+text &rarr; GML representation of a geometry
+
+<h4>Example</h4>
+<pre> geomFromGML( '<gml:LineString srsName="EPSG:4326"><gml:coordinates>4,4 5,5 6,6</gml:coordinates></gml:LineString>') &rarr; returns a geometry</pre>
+

resources/function_help/geomFromWKT

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+<h3>geomFromWKT function</h3>
+Returns a geometry created from a Well-Known Text (WKT) representation.
+
+<h4>Syntax</h4>
+<pre>geomFromWKT(text)</pre>
+
+<h4>Arguments</h4>
+text &rarr; Well-Known Text (WKT) representation of a geometry
+
+<h4>Example</h4>
+<pre> geomFromWKT( 'POINT(4 5)' ) &rarr; returns a geometry</pre>
+

resources/function_help/geomToWKT

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+<h3>geomToWKT function</h3>
+Returns the Well-Known Text (WKT) representation of the geometry without SRID metadata.
+
+<h4>Syntax</h4>
+<pre>geomToWKT($geometry)</pre>
+
+<h4>Arguments</h4>
+$geometry &rarr;  geometry of your current feature
+
+<h4>Example</h4>
+<pre> geomToWKT( $geometry ) &rarr; POINT(6 50)</pre>
+

resources/function_help/intersection

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+<h3>intersection function</h3>
+Returns a geometry that represents the shared portion of geometry a and geometry b.
+
+<h4>Syntax</h4>
+<pre>intersection( geometry a , geometry b)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> geomToWKT( intersection( geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 )' ))  )   &rarr; returns LINESTRING(3 3, 4 4)</pre>

resources/function_help/intersects

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+<h3>intersects function</h3>
+Returns 1 if the geometries spatially intersect (share any portion of space) and 0 if they don't.
+
+<h4>Syntax</h4>
+<pre>intersects( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> intersects( geomFromWKT( 'POINT(4 4)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))    &rarr; returns 1</pre>
+<pre> intersects( geomFromWKT( 'POINT(4 5)' ) , geomFromWKT( 'POINT(5 5)' ))             &rarr; returns 0</pre>

resources/function_help/overlaps

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+<h3>overlaps function</h3>
+Returns 1 if the Geometries share space, are of the same dimension, but are not completely contained by each other.
+
+<h4>Syntax</h4>
+<pre>overlaps( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> overlaps( geomFromWKT( 'LINESTRING(3 5 , 4 4 , 5 5 , 5 3)'  ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))   &rarr; returns 1</pre>
+<pre> overlaps( geomFromWKT( 'LINESTRING(0 0 , 1 1)'  ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))    &rarr; returns 0</pre>

resources/function_help/symDifference

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+<h3>symDifference function</h3>
+Returns a geometry that represents the portions of a and b that do not intersect.
+
+<h4>Syntax</h4>
+<pre>symDifference( geometry a, geometry b)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> geomToWKT( symDifference(  geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ) , geomFromWKT( 'LINESTRING(3 3 , 8 8)' ))   )   &rarr; returns LINESTRING(5 5, 8 8)</pre>

resources/function_help/touches

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+<h3>touches function</h3>
+Returns 1 if the geometries have at least one point in common, but their interiors do not intersect.
+
+<h4>Syntax</h4>
+<pre>touches( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> touches( geomFromWKT( 'LINESTRING(5 3 , 4 4)'  ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))    &rarr; returns 1</pre>
+<pre> touches( geomFromWKT( 'POINT(4 4)' ) , geomFromWKT( 'POINT(5 5)' ))                     &rarr; returns 0</pre>

resources/function_help/union

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+<h3>union function</h3>
+Returns a geometry that represents the point set union of the geometries.
+
+<h4>Syntax</h4>
+<pre>union( $geometry , $geometry)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> geomToWKT( union( geomFromWKT( 'POINT(4 4)' ) , geomFromWKT( 'POINT(5 5)' ))  )   &rarr; returns MULTIPOINT(4 4, 5 5)</pre>

resources/function_help/within

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+<h3>within function</h3>
+Returns 1 if the geometry a is completely inside geometry b
+
+<h4>Syntax</h4>
+<pre>within( geometry a , geometry b)</pre>
+
+<h4>Arguments</h4>
+geometry &rarr; geometry
+geometry &rarr; geometry
+
+<h4>Example</h4>
+<pre> within( geomFromWKT( 'POINT( 0.5 0.5 )') , geomFromWKT('POLYGON((0 0 , 0 1 , 1 1 , 1 0 , 0 0 ))' ) )    &rarr; returns 1</pre>
+<pre> within( geomFromWKT( 'POINT( 5 5 )') , geomFromWKT('POLYGON((0 0 , 0 1 , 1 1 , 1 0 , 0 0 ))' ) )        &rarr; returns 0</pre>