checkpoint autogen tile

[anneal.git] / src / edu / berkeley / qfat / geom / Polygon.java

diff --git a/src/edu/berkeley/qfat/geom/Polygon.java b/src/edu/berkeley/qfat/geom/Polygon.java
new file mode 100644 (file)
index 0000000..e2d3bc5
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+++ b/src/edu/berkeley/qfat/geom/Polygon.java
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+package edu.berkeley.qfat.geom;
+import javax.media.opengl.*;
+import java.util.*;
+import edu.berkeley.qfat.Mesh;
+
+// FIXME: numerical stability issues galore
+/** a planar, convex, possibly infinite/open polygon */
+public final class Polygon {
+
+    public final Plane plane;
+    
+    private final HalfSpace[] halfSpaces;
+
+    public Polygon(Plane plane) { this(plane, new HalfSpace[0]); }
+
+    public Polygon(Plane plane, HalfSpace[] halfSpaces) {
+        this.plane = plane;
+        this.halfSpaces = halfSpaces;
+    }
+
+    public Polygon intersect(HalfSpace hs) {
+        HalfSpace[] newHalfSpaces = new HalfSpace[halfSpaces.length+1];
+        System.arraycopy(halfSpaces, 0, newHalfSpaces, 0, halfSpaces.length);
+        newHalfSpaces[newHalfSpaces.length-1] = hs;
+        return new Polygon(plane, newHalfSpaces);
+    }
+
+    public Triangle[] tesselate(Mesh mesh) {
+        // FIXME: check for closedness
+        // find a starting point
+        HashSet<Segment> segments = new HashSet<Segment>();
+        int i;
+        for(i=0; i<halfSpaces.length; i++) {
+            Point p1=null, p2=null;
+            for(int j=0; j<halfSpaces.length; j++) {
+                if (i==j) continue;
+                Point p = plane.intersect(halfSpaces[i], halfSpaces[j]);
+                if (p==null) continue;
+                for(int k=0; k<halfSpaces.length; k++) {
+                    if (i==k || j==k) continue;
+                    //if (!halfSpaces[k].contains(p)) { p = null; break; }
+                }
+                if (p!=null) {
+                    if (p1==null) p1 = p;
+                    else if (p2==null) { if (!p.equals(p1)) p2 = p; }
+                    else throw new Error();
+                }
+            }
+            if (p1!=null && p2!=null) {
+                System.out.println("new segment: " + p1 + " " + p2);
+                segments.add(new Segment(p1, p2));
+            }
+        }
+        Vec cen = new Vec(0,0,0);
+        for(Segment s : segments)
+            cen = cen.plus(s.p1.minus(Point.ORIGIN)).plus(s.p2.minus(Point.ORIGIN));
+        Point centroid = Point.ORIGIN.plus(cen.times(1f/(2*segments.size())));
+        for(Segment s : segments) {
+            System.out.println("newt! " + s.p1 + " " + centroid + " " + s.p2 + " " + plane.norm.times(-1));
+            mesh.newT(s.p1, centroid, s.p2, plane.norm.times(-1), 0);
+        }
+        System.out.println("done");
+        return null;
+    }
+
+}