Add a minor convenience for calculating the distance to a point

Change-Id: I312727bf6858ead6c30fe20bf3abc5afc73a3a14
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

src/gui/math3d/qvector3d.cpp

@@ -347,6 +347,19 @@ QVector3D QVector3D::normal
     return crossProduct((v2 - v1), (v3 - v1)).normalized();
 }
 
+/*!
+    \since 5.1
+
+    Returns the distance from this vertex to a point defined by
+    the vertex \a point.
+
+    \sa distanceToPlane(), distanceToLine()
+*/
+float QVector3D::distanceToPoint(const QVector3D& point) const
+{
+    return (*this - point).length();
+}
+
 /*!
     Returns the distance from this vertex to a plane defined by
     the vertex \a plane and a \a normal unit vector.  The \a normal

src/gui/math3d/qvector3d.h

@@ -97,6 +97,7 @@ public:
     static QVector3D normal
         (const QVector3D& v1, const QVector3D& v2, const QVector3D& v3);
 
+    float distanceToPoint(const QVector3D& point) const;
     float distanceToPlane(const QVector3D& plane, const QVector3D& normal) const;
     float distanceToPlane(const QVector3D& plane1, const QVector3D& plane2, const QVector3D& plane3) const;
     float distanceToLine(const QVector3D& point, const QVector3D& direction) const;

tests/auto/gui/math3d/qvectornd/tst_qvectornd.cpp

@@ -128,6 +128,8 @@ private slots:
     void crossProduct();
     void normal_data();
     void normal();
+    void distanceToPoint_data();
+    void distanceToPoint();
     void distanceToPlane_data();
     void distanceToPlane();
     void distanceToLine_data();
@@ -1788,6 +1790,59 @@ void tst_QVectorND::normal()
     QVERIFY(QVector3D::normal(point, v1 + point, v2 + point) == v3.normalized());
 }
 
+// Test distance to point calculations.
+void tst_QVectorND::distanceToPoint_data()
+{
+    QTest::addColumn<float>("x1");  // Point to test for distance
+    QTest::addColumn<float>("y1");
+    QTest::addColumn<float>("z1");
+    QTest::addColumn<float>("x2");  // Point to test against
+    QTest::addColumn<float>("y2");
+    QTest::addColumn<float>("z2");
+
+    QTest::addColumn<float>("distance");
+
+    QTest::newRow("null")
+        << 0.0f << 0.0f << 0.0f
+        << 0.0f << 0.0f << 1.0f
+        << 1.0f;
+
+    QTest::newRow("on point")
+        << 0.0f << 0.0f << 0.0f
+        << 0.0f << 0.0f << 0.0f
+        << 0.0f;
+
+    QTest::newRow("off point")
+        << 0.0f << 0.0f << 0.0f
+        << 0.0f << 0.0f << 1.0f
+        << 1.0f;
+
+    QTest::newRow("off point 2")
+        << 0.0f << 0.0f << 0.0f
+        << 0.0f << 2.0f << 0.0f
+        << 2.0f;
+
+    QTest::newRow("minus point")
+        << 0.0f << 0.0f << 0.0f
+        << 0.0f << -2.0f << 0.0f
+        << 2.0f;
+}
+void tst_QVectorND::distanceToPoint()
+{
+    QFETCH(float, x1);
+    QFETCH(float, y1);
+    QFETCH(float, z1);
+    QFETCH(float, x2);
+    QFETCH(float, y2);
+    QFETCH(float, z2);
+    QFETCH(float, distance);
+
+    QVector3D v1(x1, y1, z1);
+    QVector3D v2(x2, y2, z2);
+
+    QCOMPARE(v1.distanceToPoint(v2), distance);
+}
+
 // Test distance to plane calculations.
 void tst_QVectorND::distanceToPlane_data()
 {