add extractInnerVertices()

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## **2.0** *(2024-08-xx)*
 
+**Version 2 is built with Java 17**
+
 ### Added
 * `findShortestTour()` to `PGS_PointSet`. Computes an <i>approximate</i> Traveling Salesman path for a set of points.
 * `pruneSparsePoints()` to  `PGS_PointSet`. Prunes a list of points by removing points that are considered not sufficiently dense (far away from their nearest neighbours); a counterpart to `prunePointsWithinDistance()`.
@@ -16,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `fix()` to `PGS_Processing`. Attempts to fix shapes with invalid geometry.
 * Additional method signature for `frontChainPack()` that accepts a random seed.
 * `isClockwise()` to `PGS_ShapePredicates`. Determines if the vertices of the specified shape form a clockwise loop.
+* `extractInnerVertices()` to `PGS_Meshing`. Extracts all inner vertices from a mesh.
 
 ### Changes
 * Packed circles from `PGS_CirclePacking.stochasticPack()` will now always lie within shape bounds.

README.md

@@ -546,6 +546,13 @@ Much of the functionality (but by no means all) is demonstrated below:
     <td valign="top" width="25%"><img src="resources/meshing/areaMerge.gif"></td>
     <td valign="top" width="25%"><img src="resources/meshing/innerEdges.gif"></td>
   </tr>
+
+  <tr>
+    <td align="center" valign="center"><b>Extract Inner Vertices</td>
+  </tr>
+  <tr>
+    <td valign="top" width="25%"><img src="resources/meshing/extractInnerVertices.gif"></td>
+  </tr>
 </table>
 
 ## *Geometric Optimisation*

src/main/java/micycle/pgs/PGS_Meshing.java

@@ -812,6 +812,25 @@ public static PShape extractInnerEdges(PShape mesh) {
 		return PGS_SegmentSet.dissolve(innerEdges);
 	}
 
+	/**
+	 * Extracts the inner vertices from a mesh. Inner vertices are defined as
+	 * vertices that are not part of the perimeter (nor holes) of the mesh.
+	 * 
+	 * @param mesh The mesh shape to extract inner vertices from.
+	 * @return A PShape object containing only the inner vertices of the original
+	 *         mesh.
+	 * @since 2.0
+	 */
+	public static List<PVector> extractInnerVertices(PShape mesh) {
+		var allVertices = PGS_Conversion.toPVector(mesh);
+		var perimeterVertices = PGS_Conversion.toPVector(PGS_ShapeBoolean.unionMesh(mesh));
+		var allVerticesSet = new HashSet<>(allVertices);
+		var perimeterVerticesSet = new HashSet<>(perimeterVertices);
+
+		allVerticesSet.removeAll(perimeterVerticesSet);
+		return new ArrayList<>(allVerticesSet);
+	}
+
 	/**
 	 * Merges the small faces within a mesh into their adjacent faces recursively,
 	 * ensuring that no faces smaller than a specified area remain. This process is
@@ -867,8 +886,11 @@ public static PShape splitEdges(PShape split, int parts) {
 		return PGS.polygonizeEdges(splitEdges);
 	}
 
+	/**
+	 * Applies the styling properties of oldMesh to newMesh.
+	 */
 	private static PShape applyOriginalStyling(final PShape newMesh, final PShape oldMesh) {
-		final PShapeData data = new PShapeData(oldMesh.getChild(0)); // use first child; assume global.
+		final PShapeData data = new PShapeData(oldMesh.getChildCount() > 0 ? oldMesh.getChild(0) : oldMesh); // note use first child
 		for (int i = 0; i < newMesh.getChildCount(); i++) {
 			data.applyTo(newMesh.getChild(i));
 		}