1 files changed, 113 insertions, 0 deletions
diff --git a/watchmaker/examples/src/java/main/org/uncommons/watchmaker/examples/monalisa/PolygonColourMutation.java b/watchmaker/examples/src/java/main/org/uncommons/watchmaker/examples/monalisa/PolygonColourMutation.java
new file mode 100644
index 0000000..0434646
--- /dev/null
+++ b/watchmaker/examples/src/java/main/org/uncommons/watchmaker/examples/monalisa/PolygonColourMutation.java
@@ -0,0 +1,113 @@
+//=============================================================================
+// Copyright 2006-2010 Daniel W. Dyer
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//=============================================================================
+package org.uncommons.watchmaker.examples.monalisa;
+
+import java.awt.Color;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import org.uncommons.maths.Maths;
+import org.uncommons.maths.number.ConstantGenerator;
+import org.uncommons.maths.number.NumberGenerator;
+import org.uncommons.maths.random.Probability;
+import org.uncommons.watchmaker.framework.EvolutionaryOperator;
+
+/**
+ * Evolutionary operator for mutating individual polygons.  Polygons are mutated
+ * by changing their colour and/or either adding a point, removing a point or
+ * changing the position of a point.
+ * @author Daniel Dyer
+ */
+public class PolygonColourMutation implements EvolutionaryOperator<ColouredPolygon>
+{
+    private final NumberGenerator<Probability> mutationProbability;
+    private final NumberGenerator<Double> mutationAmount;
+
+
+    /**
+     * @param mutationProbability A {@link NumberGenerator} that controls the
+     * probability that the colour will be modified.
+     * @param mutationAmount A {@link NumberGenerator} that controls the amount
+     * that the colour's components are adjusted by.
+     */
+    public PolygonColourMutation(NumberGenerator<Probability> mutationProbability,
+                                 NumberGenerator<Double> mutationAmount)
+    {
+        this.mutationProbability = mutationProbability;
+        this.mutationAmount = mutationAmount;
+    }
+
+
+    /**
+     * @param mutationProbability The probability that the colour will be modified.
+     * @param mutationAmount A {@link NumberGenerator} that controls the amount
+     * that the colour's components are adjusted by.
+     */
+    public PolygonColourMutation(Probability mutationProbability,
+                                 NumberGenerator<Double> mutationAmount)
+    {
+        this(new ConstantGenerator<Probability>(mutationProbability), mutationAmount);
+    }
+
+
+    public List<ColouredPolygon> apply(List<ColouredPolygon> polygons, Random rng)
+    {
+        List<ColouredPolygon> newPolygons = new ArrayList<ColouredPolygon>(polygons.size());
+        for (ColouredPolygon polygon : polygons)
+        {
+            Color newColour = mutateColour(polygon.getColour(), rng);
+            newPolygons.add(newColour == polygon.getColour()
+                            ? polygon
+                            : new ColouredPolygon(newColour, polygon.getVertices()));
+        }
+        return newPolygons;
+    }
+
+
+    /**
+     * Mutate the specified colour.
+     * @param colour The colour to mutate.
+     * @param rng A source of randomness.
+     * @return The (possibly) mutated colour.
+     */
+    private Color mutateColour(Color colour, Random rng)
+    {
+        if (mutationProbability.nextValue().nextEvent(rng))
+        {
+            return new Color(mutateColourComponent(colour.getRed()),
+                             mutateColourComponent(colour.getGreen()),
+                             mutateColourComponent(colour.getBlue()),
+                             mutateColourComponent(colour.getAlpha()));
+        }
+        else
+        {
+            return colour;
+        }
+    }
+
+
+    /**
+     * Adjust a single component (red, green, blue or alpha) of a colour.
+     * @param component The value to mutate.
+     * @return The mutated component value.
+     */
+    private int mutateColourComponent(int component)
+    {
+        int mutatedComponent = (int) Math.round(component + mutationAmount.nextValue());
+        mutatedComponent = Maths.restrictRange(mutatedComponent, 0, 255);
+        return mutatedComponent;
+    }
+}