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, 7 insertions, 10 deletions

diff --git a/src/gui/math3d/qquaternion.cpp b/src/gui/math3d/qquaternion.cpp
index ece4482..7206e9a 100644
--- a/src/gui/math3d/qquaternion.cpp
+++ b/src/gui/math3d/qquaternion.cpp
@@ -353,7 +353,7 @@ QQuaternion QQuaternion::fromAxisAndAngle(const QVector3D& axis, qreal angle)
     qreal s = qSin(a);
     qreal c = qCos(a);
     QVector3D ax = axis.normalized();
-    return QQuaternion(c, ax.xp * s, ax.yp * s, ax.zp * s, 1).normalized();
+    return QQuaternion(c, ax.x() * s, ax.y() * s, ax.z() * s).normalized();
 }
 
 #endif
@@ -365,19 +365,16 @@ QQuaternion QQuaternion::fromAxisAndAngle(const QVector3D& axis, qreal angle)
 QQuaternion QQuaternion::fromAxisAndAngle
         (qreal x, qreal y, qreal z, qreal angle)
 {
-    float xp = x;
-    float yp = y;
-    float zp = z;
-    qreal length = qSqrt(xp * xp + yp * yp + zp * zp);
-    if (!qIsNull(length)) {
-        xp /= length;
-        yp /= length;
-        zp /= length;
+    qreal length = qSqrt(x * x + y * y + z * z);
+    if (!qFuzzyIsNull(length - 1.0f) && !qFuzzyIsNull(length)) {
+        x /= length;
+        y /= length;
+        z /= length;
     }
     qreal a = (angle / 2.0f) * M_PI / 180.0f;
     qreal s = qSin(a);
     qreal c = qCos(a);
-    return QQuaternion(c, xp * s, yp * s, zp * s, 1).normalized();
+    return QQuaternion(c, x * s, y * s, z * s).normalized();
 }
 
 /*!