QtGui/math3d : Fix QQuaternion::getEulerAngles

When rotating M_PI_2 based on x-axis, quaternion to euler conversion
makes NaN for the x-rotation value.  This patch fixes this corner case.

Fixes: QTBUG-93600
Pick-to: 6.1 6.0 5.15
Change-Id: Ice321a80ad90dba9cf3ee3a14ec7d3d047c21bd3
Reviewed-by: Laszlo Agocs <[email protected]>
Reviewed-by: Andy Nichols <[email protected]>

2 files changed, 33 insertions, 9 deletions

diff --git a/src/gui/math3d/qquaternion.cpp b/src/gui/math3d/qquaternion.cpp
index 48e12f12fe8..ba82aaa7378 100644
--- a/src/gui/math3d/qquaternion.cpp
+++ b/src/gui/math3d/qquaternion.cpp
@@ -511,7 +511,11 @@ void QQuaternion::getEulerAngles(float *pitch, float *yaw, float *roll) const
     const float zz = zps * zps;
     const float zw = zps * wps;
 
-    *pitch = std::asin(-2.0f * (yz - xw));
+    const float sinp = -2.0f * (yz - xw);
+    if (std::abs(sinp) >= 1.0f)
+        *pitch = std::copysign(M_PI_2, sinp);
+    else
+        *pitch = std::asin(sinp);
     if (*pitch < M_PI_2) {
         if (*pitch > -M_PI_2) {
             *yaw = std::atan2(2.0f * (xz + yw), 1.0f - 2.0f * (xx + yy));
diff --git a/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp b/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
index aaf0fb7e0de..4229fa1017d 100644
--- a/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
+++ b/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
@@ -1085,35 +1085,38 @@ void tst_QQuaternion::fromEulerAngles_data()
     QTest::addColumn<float>("yaw");
     QTest::addColumn<float>("roll");
 
+    QTest::addColumn<QQuaternion>("quaternion");
+
     QTest::newRow("null")
-        << 0.0f << 0.0f << 0.0f;
+        << 0.0f << 0.0f << 0.0f << QQuaternion(1.0f, 0.0f, 0.0f, 0.0f);
 
     QTest::newRow("xonly")
-        << 90.0f << 0.0f << 0.0f;
+        << 90.0f << 0.0f << 0.0f << QQuaternion(0.707107f, 0.707107f, 0.0f, 0.0f);
 
     QTest::newRow("yonly")
-        << 0.0f << 180.0f << 0.0f;
+        << 0.0f << 180.0f << 0.0f << QQuaternion(0.0f, 0.0f, 1.0f, 0.0f);
 
     QTest::newRow("zonly")
-        << 0.0f << 0.0f << 270.0f;
+        << 0.0f << 0.0f << 270.0f << QQuaternion(-0.707107f, 0.0f, 0.0f, 0.707107f);
 
     QTest::newRow("x+z")
-        << 30.0f << 0.0f << 45.0f;
+        << 30.0f << 0.0f << 45.0f << QQuaternion(0.892399f, 0.239118f, -0.099046f, 0.369644f);
 
     QTest::newRow("x+y")
-        << 30.0f << 90.0f << 0.0f;
+        << 30.0f << 90.0f << 0.0f << QQuaternion(0.683013f, 0.183013f, 0.683013f, -0.183013f);
 
     QTest::newRow("y+z")
-        << 0.0f << 45.0f << 30.0f;
+        << 0.0f << 45.0f << 30.0f << QQuaternion(0.892399f, 0.099046f, 0.369644f, 0.239118f);
 
     QTest::newRow("complex")
-        << 30.0f << 240.0f << -45.0f;
+        << 30.0f << 240.0f << -45.0f << QQuaternion(-0.531976f, -0.43968f, 0.723317f, -0.02226f);
 }
 void tst_QQuaternion::fromEulerAngles()
 {
     QFETCH(float, pitch);
     QFETCH(float, yaw);
     QFETCH(float, roll);
+    QFETCH(QQuaternion, quaternion);
 
     // Use a straight-forward implementation of the algorithm at:
     // http://www.j3d.org/matrix_faq/matrfaq_latest.html#Q60
@@ -1129,11 +1132,22 @@ void tst_QQuaternion::fromEulerAngles()
     QVERIFY(myFuzzyCompare(answer.z(), result.z()));
     QVERIFY(myFuzzyCompare(answer.scalar(), result.scalar()));
 
+    // quaternion should be the same as the result
+    QVERIFY(myFuzzyCompare(answer.x(), quaternion.x()));
+    QVERIFY(myFuzzyCompare(answer.y(), quaternion.y()));
+    QVERIFY(myFuzzyCompare(answer.z(), quaternion.z()));
+    QVERIFY(myFuzzyCompare(answer.scalar(), quaternion.scalar()));
+
     {
         QVector3D answerEulerAngles = answer.toEulerAngles();
         QVERIFY(myFuzzyCompareDegrees(answerEulerAngles.x(), pitch));
         QVERIFY(myFuzzyCompareDegrees(answerEulerAngles.y(), yaw));
         QVERIFY(myFuzzyCompareDegrees(answerEulerAngles.z(), roll));
+
+        QVector3D quaternionEulerAngles = quaternion.toEulerAngles();
+        QVERIFY(myFuzzyCompareDegrees(quaternionEulerAngles.x(), pitch));
+        QVERIFY(myFuzzyCompareDegrees(quaternionEulerAngles.y(), yaw));
+        QVERIFY(myFuzzyCompareDegrees(quaternionEulerAngles.z(), roll));
     }
 
     answer = QQuaternion::fromEulerAngles(pitch, yaw, roll);
@@ -1148,6 +1162,12 @@ void tst_QQuaternion::fromEulerAngles()
         QVERIFY(myFuzzyCompareDegrees(answerPitch, pitch));
         QVERIFY(myFuzzyCompareDegrees(answerYaw, yaw));
         QVERIFY(myFuzzyCompareDegrees(answerRoll, roll));
+
+        float quaternionPitch, quaternionYaw, quaternionRoll;
+        quaternion.getEulerAngles(&quaternionPitch, &quaternionYaw, &quaternionRoll);
+        QVERIFY(myFuzzyCompareDegrees(quaternionPitch, pitch));
+        QVERIFY(myFuzzyCompareDegrees(quaternionYaw, yaw));
+        QVERIFY(myFuzzyCompareDegrees(quaternionRoll, roll));
     }
 }