Add spatial function st_isovist

h2gis-functions/src/main/java/org/h2gis/functions/factory/H2GISFunctions.java

@@ -31,6 +31,7 @@
 import org.h2.tools.RunScript;
 import org.h2gis.api.Function;
 import org.h2gis.api.ScalarFunction;
+import org.h2gis.functions.spatial.earth.*;
 import org.h2gis.functions.spatial.split.ST_LineIntersector;
 import org.h2gis.functions.spatial.split.ST_Split;
 import org.h2gis.functions.io.DriverManager;
@@ -112,9 +113,6 @@
 import org.h2gis.functions.spatial.distance.ST_MaxDistance;
 import org.h2gis.functions.spatial.distance.ST_ProjectPoint;
 import org.h2gis.functions.spatial.distance.ST_ShortestLine;
-import org.h2gis.functions.spatial.earth.ST_GeometryShadow;
-import org.h2gis.functions.spatial.earth.ST_SunPosition;
-import org.h2gis.functions.spatial.earth.ST_Svf;
 import org.h2gis.functions.spatial.edit.ST_AddPoint;
 import org.h2gis.functions.spatial.edit.ST_AddZ;
 import org.h2gis.functions.spatial.edit.ST_CollectionExtract;
@@ -443,7 +441,8 @@ public static Function[] getBuiltInsFunctions() {
                 new ST_Svf(),
                 new JsonWrite(),
                 new ST_ShortestLine(),
-                new ST_OrientedEnvelope()};
+                new ST_OrientedEnvelope(),
+                new ST_Isovist()};
     }
 
     /**

h2gis-functions/src/main/java/org/h2gis/functions/spatial/earth/ST_Isovist.java

@@ -0,0 +1,82 @@
+/**
+ * H2GIS is a library that brings spatial support to the H2 Database Engine
+ * <http://www.h2database.com>. H2GIS is developed by CNRS
+ * <http://www.cnrs.fr/>.
+ *
+ * This code is part of the H2GIS project. H2GIS is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * Lesser General Public License as published by the Free Software Foundation;
+ * version 3.0 of the License.
+ *
+ * H2GIS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details <http://www.gnu.org/licenses/>.
+ *
+ *
+ * For more information, please consult: <http://www.h2gis.org/>
+ * or contact directly: info_at_h2gis.org
+ */
+package org.h2gis.functions.spatial.earth;
+
+import org.h2gis.api.*;
+import org.h2gis.utilities.jts_utils.*;
+import org.locationtech.jts.geom.*;
+import org.locationtech.jts.util.*;
+
+import java.sql.*;
+
+public class ST_Isovist extends DeterministicScalarFunction {
+  public ST_Isovist() {
+    addProperty(PROP_REMARKS, "ST_Isovist takes LINESTRING(S) or POLYGON(S) as input\n"
+            + " and a maximum distance (spatial ref units). This function compute the visibility polygon" +
+            " obstructed by provided \"walls\". Provided segments will be enclosed by a circle" +
+            " defined by maximum distance parameter.");
+  }
+
+  @Override
+  public String getJavaStaticMethod() {
+    return "isovist";
+  }
+
+  /**
+   * This function compute the visibility polygon
+   * @param viewPoint Point instance, isovist location
+   * @param lineSegments Occlusion segments. Geometry collection or polygon or linestring
+   * @param maxDistance Maximum distance of view from viewPoint (spatial ref units)
+   * @return The visibility polygon
+   * @throws SQLException In case of wrong parameters
+   */
+  public static Polygon isovist(Geometry viewPoint, Geometry lineSegments, double maxDistance) throws SQLException {
+    if(!(viewPoint instanceof Point) || viewPoint.isEmpty()) {
+      throw new SQLException("First parameter of ST_Isovist must be a Point");
+    }
+    if(maxDistance <= 0) {
+      throw new SQLException("Third parameter of ST_Isovist must be a valid distance superior than 0");
+    }
+    VisibilityAlgorithm visibilityAlgorithm = new VisibilityAlgorithm(maxDistance);
+    visibilityAlgorithm.addGeometry(lineSegments);
+    return visibilityAlgorithm.getIsoVist(viewPoint.getCoordinate(), true);
+  }
+
+  /**
+   * This function compute the visibility polygon
+   * @param viewPoint Point instance, isovist location
+   * @param lineSegments Occlusion segments. Geometry collection or polygon or linestring
+   * @param maxDistance Maximum distance of view from viewPoint (spatial ref units)
+   * @param radBegin Constraint view angle start in radian
+   * @param radEnd Constraint view angle end in radian
+   * @return The visibility polygon
+   * @throws SQLException In case of wrong parameters
+   */
+  public static Geometry isovist(Geometry viewPoint, Geometry lineSegments, double maxDistance, double radBegin, double radEnd) throws SQLException {
+    Geometry isopoly = isovist(viewPoint, lineSegments, maxDistance);
+
+    // Intersects with view constrain
+    GeometricShapeFactory geometricShapeFactory = new GeometricShapeFactory();
+    geometricShapeFactory.setCentre(viewPoint.getCoordinate());
+    geometricShapeFactory.setWidth(maxDistance * 2);
+    geometricShapeFactory.setHeight(maxDistance * 2);
+    return geometricShapeFactory.createArcPolygon(radBegin, radEnd).intersection(isopoly);
+  }
+}

h2gis-functions/src/test/java/org/h2gis/functions/spatial/SpatialFunction2Test.java

@@ -951,4 +951,20 @@ public void test_ST_ShortestLine4() throws Exception {
         Assert.assertTrue(rs.next());
         assertGeometryEquals("LINESTRING (2 4, 2 4.9)", rs.getObject(1));
     }
+
+    @Test
+    public void test_ST_Isovist() throws Exception {
+        Statement st = connection.createStatement();
+        ResultSet rs = st.executeQuery("SELECT ST_Isovist('POINT (1.8 2.4)'::GEOMETRY, 'MULTIPOLYGON(((1 2, 3 2, 2 3, 1 2)),((2 4, 5 2, 5 5, 2 4)),((1 1 0, 4 1 0, 4 4 5, 1 1 0)))'::GEOMETRY, 10) as result");
+        Assert.assertTrue(rs.next());
+        assertGeometryEquals("POLYGON ((2.5 2.5, 2 3, 1 2, 2 2, 2.5 2.5))", rs.getObject(1));
+    }
+
+    @Test
+    public void test_ST_IsovistConstraint() throws Exception {
+        Statement st = connection.createStatement();
+        ResultSet rs = st.executeQuery("SELECT ST_Isovist('POINT (2 2.5)'::GEOMETRY, 'MULTIPOLYGON(((1 2, 3 2, 2 3, 1 2)),((2 4, 5 2, 5 5, 2 4)),((1 1 0, 4 1 0, 4 4 5, 1 1 0)))'::GEOMETRY, 10, 0, PI() / 2) as result");
+        Assert.assertTrue(rs.next());
+        assertGeometryEquals("POLYGON ((2 2.5, 2 3, 2.5 2.5, 2 2.5))", rs.getObject(1));
+    }
 }