collinearity test for vectors

.gitignore

@@ -4,3 +4,10 @@
 /.nb-gradle/
 VVecMath.iml
 
+/.classpath
+/.vscode
+/.project
+/.settings
+
+/bin
+

build.gradle

@@ -10,9 +10,8 @@ apply plugin: 'java'
 apply from: 'gradle/publishing.gradle'
 
 
-task wrapper(type: Wrapper) {
-  gradleVersion = '4.9'
-  distributionUrl = "https://services.gradle.org/distributions/gradle-$gradleVersion-all.zip"
+wrapper {
+  gradleVersion = '5.4'
 }
 
 apply plugin: 'java'
@@ -30,7 +29,7 @@ repositories {
 }
 
 dependencies {
-    testCompile group: 'junit', name: 'junit', version: '4.11'
+    testCompile group: 'junit', name: 'junit', version: '4.12'
 }
 
 
@@ -43,7 +42,7 @@ license {
         groovy = 'SLASHSTAR_STYLE'
         fxml   = 'XML_STYLE'
     }
-    ext.year   = '2018'
+    ext.year   = '2019'
     ext.author = 'Michael Hoffer <[email protected]>'
     exclude '**/*.svg'
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.9-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.4-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -28,7 +28,7 @@ APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+DEFAULT_JVM_OPTS='"-Xmx64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"

gradlew.bat

@@ -14,7 +14,7 @@ set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
+set DEFAULT_JVM_OPTS="-Xmx64m"
 
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome

src/main/java/eu/mihosoft/vvecmath/Matrix4d.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/ModifiableStoredVector3d.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:
@@ -32,7 +32,6 @@
  * authors and should not be interpreted as representing official policies, either expressed
  * or implied, of Michael Hoffer <[email protected]>.
  */
-
 package eu.mihosoft.vvecmath;
 
 import static eu.mihosoft.vvecmath.StoredVector3d.getStructSize;

src/main/java/eu/mihosoft/vvecmath/ModifiableVector3d.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/ModifiableVector3dImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Plane.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Spline.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Spline3D.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/StoredVector3d.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/StoredVector3dImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Transform.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Vector3d-iface.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Vector3d.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:
@@ -636,4 +636,74 @@ public default Vector3d project(Vector3d v) {
         return this.times(pScale);
     }
 
+    /**
+     * Indicates whether the two given points are collinear with this 
+     * vector/point. 
+     * 
+     * @param p2 second point
+     * @param p3 third point
+     * 
+     * @return {@code true} if all three points are collinear;
+     *         {@code false} otherwise
+     */
+     default boolean collinear(Vector3d p2, Vector3d p3) {  
+
+        // The points p1, p2, p3 are collinear (are on the same line segment)
+        // if and only if the largest of the lenghts of 
+        //
+        //   a = P1P2,
+        //   b = P1P2
+        //   c = P2P3
+        //
+        // is equal to the sum of the other two.
+        //
+        // Explanation: 
+        //
+        // If p1, p2 and p3 are on the same line then the point in the 'middle'
+        // cuts the line segment into two smaller pieces. That is the sum of the
+        // lengths of the smaller pieces is equal to the largest one.
+        //
+        // That is, the following expression determines whether the three points
+        // are collinear
+        //
+        //   boolean collinear = largest > (second + third)
+
+        double a = this.distance(p2);
+        double b = this.distance(p3);
+        double c = p2.distance(p3);
+
+        double largest;
+        double second;
+        double third;
+
+        if (a > b && a > c) {
+            // a is largest
+            largest = a;
+            second = b;
+            third = c;
+        } else if (b > a && b > c) {
+            // b is largest
+            largest = b;
+            second = a;
+            third = c;
+        } else if (c > a && c > b) {
+            // c is largest
+            largest = c;
+            second = a;
+            third = b;
+        } else {
+            // lengths are not distinct.
+            //
+            // there are two possibilities:
+            //
+            //   a: they are vertices of a equilateral triangle   -> false
+            //   b: they are zero, i.e., all points are identical -> true
+            //
+            return a == 0 && b == 0 && c == 0;
+        }
+
+        return Math.abs(largest  - (second + third)) < Plane.TOL;
+
+    }
+
 }

src/main/java/eu/mihosoft/vvecmath/Vector3dImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/VectorUtilInternal.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/main/java/eu/mihosoft/vvecmath/Vectors3d.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 Michael Hoffer <[email protected]>. All rights reserved.
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:

src/test/java/eu/mihosoft/vvecmath/Vector3dTest.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2017-2019 Michael Hoffer <[email protected]>. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ *
+ *    2. 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.
+ *
+ * If you use this software for scientific research then please cite the following publication(s):
+ *
+ * M. Hoffer, C. Poliwoda, & G. Wittum. (2013). Visual reflection library:
+ * a framework for declarative GUI programming on the Java platform.
+ * Computing and Visualization in Science, 2013, 16(4),
+ * 181–192. http://doi.org/10.1007/s00791-014-0230-y
+ *
+ * THIS SOFTWARE IS PROVIDED BY Michael Hoffer <[email protected]> "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 Michael Hoffer <[email protected]> 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.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of Michael Hoffer <[email protected]>.
+ */
+package eu.mihosoft.vvecmath;
+
+import org.junit.Test;
+
+import junit.framework.Assert;
+
+public class Vector3dTest {
+
+    @Test
+    public void collinearityTest() {
+        {
+            Vector3d p1 = Vector3d.xyz(1,1,1);
+            Vector3d p2 = p1.times(5);
+            Vector3d p3 = p1.times(10);
+
+            Assert.assertTrue("p1, p2, p3 must be collinear", p1.collinear(p2, p3));
+        }
+        {
+            Vector3d p1 = Vector3d.xyz(1,1,1);
+            Vector3d p2 = p1.times(5,5,4);
+            Vector3d p3 = p1.times(10);
+
+            Assert.assertTrue("p1, p2, p3 must not be collinear", !p1.collinear(p2, p3));
+        }
+        {
+            Vector3d p1 = Vector3d.xyz(10,10,10);
+            Vector3d p2 = Vector3d.xyz(-1,-1,-1);
+            Vector3d p3 = p1.times(5);
+
+            Assert.assertTrue("p1, p2, p3 must be collinear", p1.collinear(p2, p3));
+        }
+        {
+            Vector3d p1 = Vector3d.xyz(10,20,10);
+            Vector3d p2 = p1.clone();
+            Vector3d p3 = p2.clone();
+
+            Assert.assertTrue("p1, p2, p3 must be collinear", p1.collinear(p2, p3));
+        }
+    }
+}