Modify QMatrix4x4 and QQuaternion to use qreal internally

Some concerns were expressed about the float precision of QMatrix4x4,
which this change addresses by using qreal instead.

The QVector2D/3D/4D classes still use float internally, so that they
can be used directly in large arrays of vertex values to be uploaded
to an OpenGL server.

QQuaternion is a client-side class, and it should produce rotations
that are consistent with QMatrix4x4.  So its precision was changed too.

A consequence of this change is that the following no longer works
in a portable fashion:

    QMatrix4x4 mat;
    ...
    glLoadMatrixf(mat.constData());

The caller must now repack the argument to convert from qreal to GLfloat.

Reviewed-by: Michael Goddard
Reviewed-by: Andreas

1 files changed, 13 insertions, 16 deletions

diff --git a/tests/auto/qquaternion/tst_qquaternion.cpp b/tests/auto/qquaternion/tst_qquaternion.cpp
index 24427c3..e3c4cd6 100644
--- a/tests/auto/qquaternion/tst_qquaternion.cpp
+++ b/tests/auto/qquaternion/tst_qquaternion.cpp
@@ -98,14 +98,11 @@ private slots:
     void metaTypes();
 };
 
-// qFuzzyCompare isn't always "fuzzy" enough to handle conversion
-// between float, double, and qreal.  So create "fuzzier" compares.
-static bool fuzzyCompare(float x, float y)
-{
-    float diff = x - y;
-    if (diff < 0.0f)
-        diff = -diff;
-    return (diff < 0.001);
+// QVector3D uses float internally, which can lead to some precision
+// issues when using it with the qreal-based QQuaternion.
+static bool fuzzyCompare(qreal x, qreal y)
+{
+    return qFuzzyIsNull(float(x - y));
 }
 
 // Test the creation of QQuaternion objects in various ways:
@@ -250,8 +247,8 @@ void tst_QQuaternion::length()
     QFETCH(qreal, len);
 
     QQuaternion v(w, x, y, z);
-    QCOMPARE((float)(v.length()), (float)len);
-    QCOMPARE((float)(v.lengthSquared()), (float)(x * x + y * y + z * z + w * w));
+    QCOMPARE(v.length(), len);
+    QCOMPARE(v.lengthSquared(), x * x + y * y + z * z + w * w);
 }
 
 // Test the unit vector conversion for quaternions.
@@ -273,11 +270,11 @@ void tst_QQuaternion::normalized()
     if (v.isNull())
         QVERIFY(u.isNull());
     else
-        QCOMPARE((float)(u.length()), (float)1.0f);
-    QCOMPARE((float)(u.x() * len), (float)(v.x()));
-    QCOMPARE((float)(u.y() * len), (float)(v.y()));
-    QCOMPARE((float)(u.z() * len), (float)(v.z()));
-    QCOMPARE((float)(u.scalar() * len), (float)(v.scalar()));
+        QCOMPARE(u.length(), qreal(1.0f));
+    QCOMPARE(u.x() * len, v.x());
+    QCOMPARE(u.y() * len, v.y());
+    QCOMPARE(u.z() * len, v.z());
+    QCOMPARE(u.scalar() * len, v.scalar());
 }
 
 // Test the unit vector conversion for quaternions.
@@ -299,7 +296,7 @@ void tst_QQuaternion::normalize()
     if (isNull)
         QVERIFY(v.isNull());
     else
-        QCOMPARE((float)(v.length()), (float)1.0f);
+        QCOMPARE(v.length(), qreal(1.0f));
 }
 
 // Test the comparison operators for quaternions.