Graph Loop: Make initFromPolyline() and locateClosestVertex() more robust, report error but do not crash.

This behavior has been evaluated with a few fonts and the WIP FontView01 demo application.

3 files changed, 33 insertions, 11 deletions

diff --git a/src/jogl/classes/jogamp/graph/curve/tess/CDTriangulator2D.java b/src/jogl/classes/jogamp/graph/curve/tess/CDTriangulator2D.java
index 85a18c982..e187b1590 100644
--- a/src/jogl/classes/jogamp/graph/curve/tess/CDTriangulator2D.java
+++ b/src/jogl/classes/jogamp/graph/curve/tess/CDTriangulator2D.java
@@ -1,5 +1,5 @@
 /**
- * Copyright 2010 JogAmp Community. All rights reserved.
+ * Copyright 2010-2023 JogAmp Community. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:
@@ -83,15 +83,17 @@ public class CDTriangulator2D implements Triangulator {
     public final void addCurve(final List<Triangle> sink, final Outline polyline, final float sharpness) {
         Loop loop = getContainerLoop(polyline);
 
-        if(loop == null) {
+        if( null == loop ) {
             final Winding winding = Winding.CCW; // -> HEdge.BOUNDARY
             // Too late: polyline.setWinding(winding);
             final GraphOutline outline = new GraphOutline(polyline); // , winding);
             final GraphOutline innerPoly = extractBoundaryTriangles(sink, outline, false, sharpness);
             // vertices.addAll(polyline.getVertices());
             if( innerPoly.getGraphPoint().size() >= 3 ) {
-                loop = new Loop(innerPoly, winding);
-                loops.add(loop);
+                loop = Loop.create(innerPoly, winding);
+                if( null != loop ) {
+                    loops.add(loop);
+                }
             } else if( DEBUG ) {
                 /*
                  * Font FreeMono-Bold: ID 0 + 465: Glyph[id 465 'uni020F', advance 600, leftSideBearings 42, kerning[size 0, horiz true, cross true], shape true], OutlineShape@5e8a459[outlines 2, vertices 34]
diff --git a/src/jogl/classes/jogamp/graph/curve/tess/GraphOutline.java b/src/jogl/classes/jogamp/graph/curve/tess/GraphOutline.java
index 75192d45a..a2b789862 100644
--- a/src/jogl/classes/jogamp/graph/curve/tess/GraphOutline.java
+++ b/src/jogl/classes/jogamp/graph/curve/tess/GraphOutline.java
@@ -1,5 +1,5 @@
 /**
- * Copyright 2010 JogAmp Community. All rights reserved.
+ * Copyright 2010-2023 JogAmp Community. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:
@@ -29,11 +29,14 @@ package jogamp.graph.curve.tess;
 
 import java.util.ArrayList;
 
+import com.jogamp.graph.curve.Region;
 import com.jogamp.graph.geom.Outline;
 import com.jogamp.graph.geom.Vertex;
-import com.jogamp.graph.geom.plane.Winding;
 
 public class GraphOutline {
+    /** Debug flag for [com.]jogamp.graph.curve.* (graph.curve) */
+    /* pp */ static boolean DEBUG = Region.DEBUG; // Debug.debug("graph.curve");
+
     final private Outline outline;
     final private ArrayList<GraphVertex> controlpoints = new ArrayList<GraphVertex>(3);
 
diff --git a/src/jogl/classes/jogamp/graph/curve/tess/Loop.java b/src/jogl/classes/jogamp/graph/curve/tess/Loop.java
index 1939dcb1e..6020e7c66 100644
--- a/src/jogl/classes/jogamp/graph/curve/tess/Loop.java
+++ b/src/jogl/classes/jogamp/graph/curve/tess/Loop.java
@@ -1,5 +1,5 @@
 /**
- * Copyright 2010 JogAmp Community. All rights reserved.
+ * Copyright 2010-2023 JogAmp Community. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:
@@ -35,7 +35,6 @@ import com.jogamp.graph.geom.plane.Winding;
 import com.jogamp.graph.geom.Triangle;
 import com.jogamp.opengl.math.Vec3f;
 import com.jogamp.opengl.math.VectorUtil;
-import com.jogamp.opengl.math.Vert2fImmutable;
 import com.jogamp.opengl.math.geom.AABBox;
 
 public class Loop {
@@ -43,11 +42,16 @@ public class Loop {
     private final AABBox box = new AABBox();
     private GraphOutline initialOutline = null;
 
-    public Loop(final GraphOutline polyline, final Winding winding){
+    private Loop(final GraphOutline polyline, final Winding winding){
         initialOutline = polyline;
         this.root = initFromPolyline(initialOutline, winding);
     }
 
+    public static Loop create(final GraphOutline polyline, final Winding winding) {
+        final Loop res = new Loop(polyline, winding);
+        return null != res.root ? res : null;
+    }
+
     public HEdge getHEdge(){
         return root;
     }
@@ -116,7 +120,11 @@ public class Loop {
         final ArrayList<GraphVertex> vertices = outline.getGraphPoint();
 
         if(vertices.size()<3) {
-            throw new IllegalArgumentException("outline's vertices < 3: " + vertices.size());
+            System.err.println( "Graph: Loop.initFromPolyline: GraphOutline's vertices < 3: " + vertices.size() );
+            if( GraphOutline.DEBUG ) {
+                Thread.dumpStack();
+            }
+            return null;
         }
         final Winding hasWinding = getWinding( vertices ); // requires area-winding detection
 
@@ -183,9 +191,18 @@ public class Loop {
     public void addConstraintCurve(final GraphOutline polyline) {
         //        GraphOutline outline = new GraphOutline(polyline);
         /**needed to generate vertex references.*/
-        initFromPolyline(polyline, Winding.CW); // -> HEdge.HOLE
+        if( null == initFromPolyline(polyline, Winding.CW) ) { // -> HEdge.HOLE
+            return;
+        }
 
         final GraphVertex v3 = locateClosestVertex(polyline);
+        if( null == v3 ) {
+            System.err.println( "Graph: Loop.locateClosestVertex returns null; root valid? "+(null!=root));
+            if( GraphOutline.DEBUG ) {
+                Thread.dumpStack();
+            }
+            return;
+        }
         final HEdge v3Edge = v3.findBoundEdge();
         final HEdge v3EdgeP = v3Edge.getPrev();
         final HEdge crossEdge = new HEdge(root.getGraphPoint(), HEdge.INNER);