Added intersect and union helpers.

src/main/java/pythagoras/f/Rectangles.java

@@ -0,0 +1,32 @@
+//
+// $Id$
+
+package pythagoras.f;
+
+/**
+ * Rectangle-related utility methods.
+ */
+public class Rectangles
+{
+    /**
+     * Intersects the supplied two rectangles, writing the result into {@link dst}.
+     */
+    public static void intersect (IRectangle src1, IRectangle src2, Rectangle dst) {
+        float x1 = Math.max(src1.getMinX(), src2.getMinX());
+        float y1 = Math.max(src1.getMinY(), src2.getMinY());
+        float x2 = Math.min(src1.getMaxX(), src2.getMaxX());
+        float y2 = Math.min(src1.getMaxY(), src2.getMaxY());
+        dst.setBounds(x1, y1, x2 - x1, y2 - y1);
+    }
+
+    /**
+     * Unions the supplied two rectangles, writing the result into {@link dst}.
+     */
+    public static void union (IRectangle src1, IRectangle src2, Rectangle dst) {
+        float x1 = Math.min(src1.getMinX(), src2.getMinX());
+        float y1 = Math.min(src1.getMinY(), src2.getMinY());
+        float x2 = Math.max(src1.getMaxX(), src2.getMaxX());
+        float y2 = Math.max(src1.getMaxY(), src2.getMaxY());
+        dst.setBounds(x1, y1, x2 - x1, y2 - y1);
+    }
+}