implement equals(), hashCode(), and isSimilar() for bounding volumes (#2252)

* implement equals() and hashCode() for BoundingBox

* implement equals() and hashCode() for BoundingSphere

* implement isSimilar() for BoundingBox

* implement isSimilar() for BoundingSphere

* BoundingSphere:  add comments to emphasize the treatment of checkPlane

* TestBoundingSphere:  test equals() and isSimilar()

* jme3-core tests:  add the TestBoundingBox class

* BoundingVolume:  add equals() and hashCode() methods

* utilize super.equals() and super.hashCode()

* refactor to utilize Objects.hash()

Author: stephengold

jme3-core/src/main/java/com/jme3/bounding/BoundingBox.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2021 jMonkeyEngine
+ * Copyright (c) 2009-2024 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -46,6 +46,7 @@
 import java.io.IOException;
 import java.nio.FloatBuffer;
 //import com.jme.scene.TriMesh;
+import java.util.Objects;
 
 /**
  * <code>BoundingBox</code> describes a bounding volume as an axis-aligned box.
@@ -587,6 +588,76 @@ public BoundingVolume clone(BoundingVolume store) {
         return rVal;
     }
 
+    /**
+     * Tests for exact equality with the argument, distinguishing -0 from 0. If
+     * {@code other} is null, false is returned. Either way, the current
+     * instance is unaffected.
+     *
+     * @param other the object to compare (may be null, unaffected)
+     * @return true if {@code this} and {@code other} have identical values,
+     *     otherwise false
+     */
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof BoundingBox)) {
+            return false;
+        }
+
+        if (this == other) {
+            return true;
+        }
+
+        BoundingBox otherBoundingBox = (BoundingBox) other;
+        if (Float.compare(xExtent, otherBoundingBox.xExtent) != 0) {
+            return false;
+        } else if (Float.compare(yExtent, otherBoundingBox.yExtent) != 0) {
+            return false;
+        } else if (Float.compare(zExtent, otherBoundingBox.zExtent) != 0) {
+            return false;
+        } else {
+            return super.equals(otherBoundingBox);
+        }
+    }
+
+    /**
+     * Returns a hash code. If two bounding boxes have identical values, they
+     * will have the same hash code. The current instance is unaffected.
+     *
+     * @return a 32-bit value for use in hashing
+     */
+    @Override
+    public int hashCode() {
+        int hash = Objects.hash(xExtent, yExtent, zExtent);
+        hash = 59 * hash + super.hashCode();
+
+        return hash;
+    }
+
+    /**
+     * Tests for approximate equality with the specified bounding box, using the
+     * specified tolerance. If {@code other} is null, false is returned. Either
+     * way, the current instance is unaffected.
+     *
+     * @param aabb the bounding box to compare (unaffected) or null for none
+     * @param epsilon the tolerance for each component
+     * @return true if all components are within tolerance, otherwise false
+     */
+    public boolean isSimilar(BoundingBox aabb, float epsilon) {
+        if (aabb == null) {
+            return false;
+        } else if (Float.compare(Math.abs(aabb.xExtent - xExtent), epsilon) > 0) {
+            return false;
+        } else if (Float.compare(Math.abs(aabb.yExtent - yExtent), epsilon) > 0) {
+            return false;
+        } else if (Float.compare(Math.abs(aabb.zExtent - zExtent), epsilon) > 0) {
+            return false;
+        } else if (!center.isSimilar(aabb.getCenter(), epsilon)) {
+            return false;
+        }
+        // The checkPlane field is ignored.
+        return true;
+    }
+
     /**
      * <code>toString</code> returns the string representation of this object.
      * The form is: "[Center: vector xExtent: X.XX yExtent: Y.YY zExtent:

jme3-core/src/main/java/com/jme3/bounding/BoundingSphere.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2021 jMonkeyEngine
+ * Copyright (c) 2009-2024 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -43,6 +43,7 @@
 import com.jme3.util.TempVars;
 import java.io.IOException;
 import java.nio.FloatBuffer;
+import java.util.Objects;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -651,6 +652,68 @@ public BoundingVolume clone(BoundingVolume store) {
         return new BoundingSphere(radius, center.clone());
     }
 
+    /**
+     * Tests for exact equality with the argument, distinguishing -0 from 0. If
+     * {@code other} is null, false is returned. Either way, the current
+     * instance is unaffected.
+     *
+     * @param other the object to compare (may be null, unaffected)
+     * @return true if {@code this} and {@code other} have identical values,
+     *     otherwise false
+     */
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof BoundingSphere)) {
+            return false;
+        }
+
+        if (this == other) {
+            return true;
+        }
+
+        BoundingSphere otherBoundingSphere = (BoundingSphere) other;
+        if (Float.compare(radius, otherBoundingSphere.getRadius()) != 0) {
+            return false;
+        } else {
+            return super.equals(otherBoundingSphere);
+        }
+    }
+
+    /**
+     * Returns a hash code. If two bounding boxes have identical values, they
+     * will have the same hash code. The current instance is unaffected.
+     *
+     * @return a 32-bit value for use in hashing
+     */
+    @Override
+    public int hashCode() {
+        int hash = Objects.hash(radius);
+        hash = 59 * hash + super.hashCode();
+
+        return hash;
+    }
+
+    /**
+     * Tests for approximate equality with the specified bounding sphere, using
+     * the specified tolerance. If {@code other} is null, false is returned.
+     * Either way, the current instance is unaffected.
+     *
+     * @param sphere the bounding sphere to compare (unaffected) or null for none
+     * @param epsilon the tolerance for each component
+     * @return true if all components are within tolerance, otherwise false
+     */
+    public boolean isSimilar(BoundingSphere sphere, float epsilon) {
+        if (sphere == null) {
+            return false;
+        } else if (Float.compare(Math.abs(sphere.getRadius() - radius), epsilon) > 0) {
+            return false;
+        } else if (!center.isSimilar(sphere.getCenter(), epsilon)) {
+            return false;
+        }
+        // The checkPlane field is ignored.
+        return true;
+    }
+
     /**
      * <code>toString</code> returns the string representation of this object.
      * The form is: "Radius: RRR.SSSS Center: vector".

jme3-core/src/main/java/com/jme3/bounding/BoundingVolume.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2021 jMonkeyEngine
+ * Copyright (c) 2009-2024 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -40,6 +40,7 @@
 import com.jme3.util.TempVars;
 import java.io.IOException;
 import java.nio.FloatBuffer;
+import java.util.Objects;
 
 /**
  * <code>BoundingVolume</code> defines an interface for dealing with
@@ -180,6 +181,48 @@ public final BoundingVolume transform(Transform trans) {
      */
     public abstract BoundingVolume clone(BoundingVolume store);
 
+    /**
+     * Tests for exact equality with the argument, distinguishing -0 from 0. If
+     * {@code other} is null, false is returned. Either way, the current
+     * instance is unaffected.
+     *
+     * @param other the object to compare (may be null, unaffected)
+     * @return true if {@code this} and {@code other} have identical values,
+     *     otherwise false
+     */
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof BoundingVolume)) {
+            return false;
+        }
+
+        if (this == other) {
+            return true;
+        }
+
+        BoundingVolume otherBoundingVolume = (BoundingVolume) other;
+        if (!center.equals(otherBoundingVolume.getCenter())) {
+            return false;
+        }
+        // The checkPlane field is ignored.
+
+        return true;
+    }
+
+    /**
+     * Returns a hash code. If two bounding volumes have identical values, they
+     * will have the same hash code. The current instance is unaffected.
+     *
+     * @return a 32-bit value for use in hashing
+     */
+    @Override
+    public int hashCode() {
+        int hash = Objects.hash(center);
+        // The checkPlane field is ignored.
+
+        return hash;
+    }
+
     public final Vector3f getCenter() {
         return center;
     }

jme3-core/src/test/java/com/jme3/bounding/TestBoundingBox.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2024 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.jme3.bounding;
+
+import com.jme3.math.Vector3f;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Test cases for the BoundingBox class.
+ *
+ * @author Stephen Gold
+ */
+public class TestBoundingBox {
+    /**
+     * Verify that equals() behaves as expected.
+     */
+    @Test
+    public void testEquals() {
+        BoundingBox bb1 = new BoundingBox(new Vector3f(3f, 4f, 5f), 0f, 1f, 2f);
+        BoundingBox bb2
+                = new BoundingBox(new Vector3f(3f, 4f, 5f), -0f, 1f, 2f);
+
+        BoundingBox bb3 = new BoundingBox(new Vector3f(3f, 0f, 2f), 9f, 8f, 7f);
+        BoundingBox bb4
+                = new BoundingBox(new Vector3f(3f, -0f, 2f), 9f, 8f, 7f);
+
+        BoundingBox bb5 = new BoundingBox(new Vector3f(4f, 5f, 6f), 9f, 8f, 7f);
+        BoundingBox bb6 = (BoundingBox) bb5.clone();
+        bb6.setCheckPlane(1);
+
+        // Clones are equal to their base instances:
+        Assert.assertEquals(bb1, bb1.clone());
+        Assert.assertEquals(bb2, bb2.clone());
+        Assert.assertEquals(bb3, bb3.clone());
+        Assert.assertEquals(bb4, bb4.clone());
+        Assert.assertEquals(bb5, bb5.clone());
+        Assert.assertEquals(bb6, bb6.clone());
+
+        Assert.assertNotEquals(bb1, bb2); // because their extents differ
+        Assert.assertNotEquals(bb3, bb4); // because their centers differ
+        Assert.assertEquals(bb5, bb6); // because check planes are ignored
+    }
+
+    /**
+     * Verify that isSimilar() behaves as expected.
+     */
+    @Test
+    public void testIsSimilar() {
+        BoundingBox bb1 = new BoundingBox(new Vector3f(3f, 4f, 5f), 0f, 1f, 2f);
+        BoundingBox bb2
+                = new BoundingBox(new Vector3f(3f, 4f, 5f), 0f, 1.1f, 2f);
+
+        BoundingBox bb3 = new BoundingBox(new Vector3f(3f, 4f, 2f), 9f, 8f, 7f);
+        BoundingBox bb4
+                = new BoundingBox(new Vector3f(3f, 3.9f, 2f), 9f, 8f, 7f);
+
+        BoundingBox bb5 = new BoundingBox(new Vector3f(4f, 5f, 6f), 9f, 8f, 7f);
+        BoundingBox bb6 = (BoundingBox) bb5.clone();
+        bb6.setCheckPlane(1);
+
+        Assert.assertFalse(bb1.isSimilar(bb2, 0.09999f));
+        Assert.assertTrue(bb1.isSimilar(bb2, 0.10001f));
+
+        Assert.assertFalse(bb3.isSimilar(bb4, 0.09999f));
+        Assert.assertTrue(bb3.isSimilar(bb4, 0.10001f));
+
+        Assert.assertTrue(bb5.isSimilar(bb6, 0f)); // check planes are ignored
+    }
+}

jme3-core/src/test/java/com/jme3/bounding/TestBoundingSphere.java

@@ -41,6 +41,57 @@
  * @author Stephen Gold
  */
 public class TestBoundingSphere {
+    /**
+     * Verify that equals() behaves as expected.
+     */
+    @Test
+    public void testEquals() {
+        BoundingSphere bs1 = new BoundingSphere(0f, new Vector3f(3f, 4f, 5f));
+        BoundingSphere bs2 = new BoundingSphere(-0f, new Vector3f(3f, 4f, 5f));
+
+        BoundingSphere bs3 = new BoundingSphere(1f, new Vector3f(3f, 0f, 2f));
+        BoundingSphere bs4 = new BoundingSphere(1f, new Vector3f(3f, -0f, 2f));
+
+        BoundingSphere bs5 = new BoundingSphere(2f, new Vector3f(4f, 5f, 6f));
+        BoundingSphere bs6 = (BoundingSphere) bs5.clone();
+        bs6.setCheckPlane(1);
+
+        // Clones are equal to their base instances:
+        Assert.assertEquals(bs1, bs1.clone());
+        Assert.assertEquals(bs2, bs2.clone());
+        Assert.assertEquals(bs3, bs3.clone());
+        Assert.assertEquals(bs4, bs4.clone());
+        Assert.assertEquals(bs5, bs5.clone());
+        Assert.assertEquals(bs6, bs6.clone());
+
+        Assert.assertNotEquals(bs1, bs2); // because their radii differ
+        Assert.assertNotEquals(bs3, bs4); // because their centers differ
+        Assert.assertEquals(bs5, bs6); // because check planes are ignored
+    }
+
+    /**
+     * Verify that isSimilar() behaves as expected.
+     */
+    @Test
+    public void testIsSimilar() {
+        BoundingSphere bs1 = new BoundingSphere(0f, new Vector3f(3f, 4f, 5f));
+        BoundingSphere bs2 = new BoundingSphere(0.1f, new Vector3f(3f, 4f, 5f));
+
+        BoundingSphere bs3 = new BoundingSphere(1f, new Vector3f(3f, 4f, 2f));
+        BoundingSphere bs4 = new BoundingSphere(1f, new Vector3f(3f, 3.9f, 2f));
+
+        BoundingSphere bs5 = new BoundingSphere(2f, new Vector3f(4f, 5f, 6f));
+        BoundingSphere bs6 = (BoundingSphere) bs5.clone();
+        bs6.setCheckPlane(1);
+
+        Assert.assertFalse(bs1.isSimilar(bs2, 0.09999f));
+        Assert.assertTrue(bs1.isSimilar(bs2, 0.10001f));
+
+        Assert.assertFalse(bs3.isSimilar(bs4, 0.09999f));
+        Assert.assertTrue(bs3.isSimilar(bs4, 0.10001f));
+
+        Assert.assertTrue(bs5.isSimilar(bs6, 0f)); // check planes are ignored
+    }
 
     /**
      * Verify that an infinite bounding sphere can be merged with a very