iverase commented on a change in pull request #726: LUCENE-8632: New XYShape
Field and Queries for indexing and searching general cartesian geometries
URL: https://github.com/apache/lucene-solr/pull/726#discussion_r298475736
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File path: lucene/sandbox/src/java/org/apache/lucene/geo/Tessellator.java
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@@ -119,17 +118,67 @@ private Tessellator() {}
return result;
}
+
+ public static final List<Triangle> tessellate(final XYPolygon polygon) {
+ // Attempt to establish a doubly-linked list of the provided shell points
(should be CCW, but this will correct);
+ // then filter instances of intersections.
+ Node outerNode = createDoublyLinkedList(polygon, 0, WindingOrder.CW);
+ // If an outer node hasn't been detected, the shape is malformed. (must
comply with OGC SFA specification)
+ if(outerNode == null) {
+ throw new IllegalArgumentException("Malformed shape detected in
Tessellator!");
+ }
+
+ // Determine if the specified list of points contains holes
+ if (polygon.numHoles() > 0) {
+ // Eliminate the hole triangulation.
+ outerNode = eliminateHoles(polygon, outerNode);
+ }
+
+ // If the shape crosses VERTEX_THRESHOLD, use z-order curve hashing:
+ final boolean mortonOptimized;
+ {
+ int threshold = VERTEX_THRESHOLD - polygon.numPoints();
+ for (int i = 0; threshold >= 0 && i < polygon.numHoles(); ++i) {
+ threshold -= polygon.getHole(i).numPoints();
+ }
+
+ // Link polygon nodes in Z-Order
+ mortonOptimized = threshold < 0;
+ if (mortonOptimized == true) {
+ sortByMorton(outerNode);
+ }
+ }
+ // Calculate the tessellation using the doubly LinkedList.
+ List<Triangle> result = earcutLinkedList(polygon, outerNode, new
ArrayList<>(), State.INIT, mortonOptimized);
+ if (result.size() == 0) {
+ throw new IllegalArgumentException("Unable to Tessellate shape [" +
polygon + "]. Possible malformed shape detected.");
+ }
+
+ return result;
+ }
+
+ private static final Node createDoublyLinkedList(XYPolygon polygon, int
startIndex, final WindingOrder windingOrder) {
Review comment:
We can remove this method and make the tessellate method call directly the
other one in either case (Polygon and XYPolygon)
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