Make gui/math3d classes use float rather than qreal

This corrects the mismatch between using floats for internal storage
and qreal in the API of QVector*D which leads to lots of implicit
casts between double and float.

This change also stops users from being surprised by the loss of
precision when using these classes on desktop platforms and removes
the need for the private constructors taking a dummy int as the final
argument.

The QMatrix4x4 and QQuaternion classes have been changed to use float
for their internal storage since these are meant to be used in
conjunction with the QVector*D classes. This is to prevent unexpected
loss of precision and to improve performance.

The on-disk format has also been changed from double to float thereby
reducing the storage required when streaming vectors and matrices. This
is potentially a large saving when working with complex 3D meshes etc.

This also has a significant performance improvement when passing
matrices to QOpenGLShaderProgram (and QGLShaderProgram) as we no
longer have to iterate and convert the data to floats. This is
an operation that could easily be needed many times per frame.

This change also opens the door for further optimisations of these
classes to be implemented by using SIMD intrinsics.

This needs to be applied in conjunction with

https://codereview.qt-project.org/#change,33548

Task-number: QTBUG-21035
Task-number: QTBUG-20661
Change-Id: I9321b06040ffb93ae1cbd72fd2013267ac901b2e
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

1 files changed, 44 insertions, 44 deletions

diff --git a/src/gui/math3d/qquaternion.cpp b/src/gui/math3d/qquaternion.cpp
index 79cdb36724..b0133881c3 100644
--- a/src/gui/math3d/qquaternion.cpp
+++ b/src/gui/math3d/qquaternion.cpp
@@ -68,7 +68,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn QQuaternion::QQuaternion(qreal scalar, qreal xpos, qreal ypos, qreal zpos)
+    \fn QQuaternion::QQuaternion(float scalar, float xpos, float ypos, float zpos)
 
     Constructs a quaternion with the vector (\a xpos, \a ypos, \a zpos)
     and \a scalar.
@@ -77,7 +77,7 @@ QT_BEGIN_NAMESPACE
 #ifndef QT_NO_VECTOR3D
 
 /*!
-    \fn QQuaternion::QQuaternion(qreal scalar, const QVector3D& vector)
+    \fn QQuaternion::QQuaternion(float scalar, const QVector3D& vector)
 
     Constructs a quaternion vector from the specified \a vector and
     \a scalar.
@@ -104,7 +104,7 @@ QT_BEGIN_NAMESPACE
 #endif
 
 /*!
-    \fn void QQuaternion::setVector(qreal x, qreal y, qreal z)
+    \fn void QQuaternion::setVector(float x, float y, float z)
 
     Sets the vector component of this quaternion to (\a x, \a y, \a z).
 
@@ -143,7 +143,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn qreal QQuaternion::x() const
+    \fn float QQuaternion::x() const
 
     Returns the x coordinate of this quaternion's vector.
 
@@ -151,7 +151,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn qreal QQuaternion::y() const
+    \fn float QQuaternion::y() const
 
     Returns the y coordinate of this quaternion's vector.
 
@@ -159,7 +159,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn qreal QQuaternion::z() const
+    \fn float QQuaternion::z() const
 
     Returns the z coordinate of this quaternion's vector.
 
@@ -167,7 +167,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn qreal QQuaternion::scalar() const
+    \fn float QQuaternion::scalar() const
 
     Returns the scalar component of this quaternion.
 
@@ -175,7 +175,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn void QQuaternion::setX(qreal x)
+    \fn void QQuaternion::setX(float x)
 
     Sets the x coordinate of this quaternion's vector to the given
     \a x coordinate.
@@ -184,7 +184,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn void QQuaternion::setY(qreal y)
+    \fn void QQuaternion::setY(float y)
 
     Sets the y coordinate of this quaternion's vector to the given
     \a y coordinate.
@@ -193,7 +193,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn void QQuaternion::setZ(qreal z)
+    \fn void QQuaternion::setZ(float z)
 
     Sets the z coordinate of this quaternion's vector to the given
     \a z coordinate.
@@ -202,7 +202,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn void QQuaternion::setScalar(qreal scalar)
+    \fn void QQuaternion::setScalar(float scalar)
 
     Sets the scalar component of this quaternion to \a scalar.
 
@@ -214,7 +214,7 @@ QT_BEGIN_NAMESPACE
 
     \sa lengthSquared(), normalized()
 */
-qreal QQuaternion::length() const
+float QQuaternion::length() const
 {
     return qSqrt(xp * xp + yp * yp + zp * zp + wp * wp);
 }
@@ -224,7 +224,7 @@ qreal QQuaternion::length() const
 
     \sa length()
 */
-qreal QQuaternion::lengthSquared() const
+float QQuaternion::lengthSquared() const
 {
     return xp * xp + yp * yp + zp * zp + wp * wp;
 }
@@ -323,7 +323,7 @@ QVector3D QQuaternion::rotatedVector(const QVector3D& vector) const
 */
 
 /*!
-    \fn QQuaternion &QQuaternion::operator*=(qreal factor)
+    \fn QQuaternion &QQuaternion::operator*=(float factor)
 
     Multiplies this quaternion's components by the given \a factor, and
     returns a reference to this quaternion.
@@ -339,7 +339,7 @@ QVector3D QQuaternion::rotatedVector(const QVector3D& vector) const
 */
 
 /*!
-    \fn QQuaternion &QQuaternion::operator/=(qreal divisor)
+    \fn QQuaternion &QQuaternion::operator/=(float divisor)
 
     Divides this quaternion's components by the given \a divisor, and
     returns a reference to this quaternion.
@@ -353,15 +353,15 @@ QVector3D QQuaternion::rotatedVector(const QVector3D& vector) const
     Creates a normalized quaternion that corresponds to rotating through
     \a angle degrees about the specified 3D \a axis.
 */
-QQuaternion QQuaternion::fromAxisAndAngle(const QVector3D& axis, qreal angle)
+QQuaternion QQuaternion::fromAxisAndAngle(const QVector3D& axis, float angle)
 {
     // Algorithm from:
     // http://www.j3d.org/matrix_faq/matrfaq_latest.html#Q56
     // We normalize the result just in case the values are close
     // to zero, as suggested in the above FAQ.
-    qreal a = (angle / 2.0f) * M_PI / 180.0f;
-    qreal s = qSin(a);
-    qreal c = qCos(a);
+    float a = (angle / 2.0f) * M_PI / 180.0f;
+    float s = sinf(a);
+    float c = cosf(a);
     QVector3D ax = axis.normalized();
     return QQuaternion(c, ax.x() * s, ax.y() * s, ax.z() * s).normalized();
 }
@@ -373,17 +373,17 @@ QQuaternion QQuaternion::fromAxisAndAngle(const QVector3D& axis, qreal angle)
     \a angle degrees about the 3D axis (\a x, \a y, \a z).
 */
 QQuaternion QQuaternion::fromAxisAndAngle
-        (qreal x, qreal y, qreal z, qreal angle)
+        (float x, float y, float z, float angle)
 {
-    qreal length = qSqrt(x * x + y * y + z * z);
+    float 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);
+    float a = (angle / 2.0f) * M_PI / 180.0f;
+    float s = qSin(a);
+    float c = qCos(a);
     return QQuaternion(c, x * s, y * s, z * s).normalized();
 }
 
@@ -424,7 +424,7 @@ QQuaternion QQuaternion::fromAxisAndAngle
 */
 
 /*!
-    \fn const QQuaternion operator*(qreal factor, const QQuaternion &quaternion)
+    \fn const QQuaternion operator*(float factor, const QQuaternion &quaternion)
     \relates QQuaternion
 
     Returns a copy of the given \a quaternion,  multiplied by the
@@ -434,7 +434,7 @@ QQuaternion QQuaternion::fromAxisAndAngle
 */
 
 /*!
-    \fn const QQuaternion operator*(const QQuaternion &quaternion, qreal factor)
+    \fn const QQuaternion operator*(const QQuaternion &quaternion, float factor)
     \relates QQuaternion
 
     Returns a copy of the given \a quaternion,  multiplied by the
@@ -466,7 +466,7 @@ QQuaternion QQuaternion::fromAxisAndAngle
 */
 
 /*!
-    \fn const QQuaternion operator/(const QQuaternion &quaternion, qreal divisor)
+    \fn const QQuaternion operator/(const QQuaternion &quaternion, float divisor)
     \relates QQuaternion
 
     Returns the QQuaternion object formed by dividing all components of
@@ -495,7 +495,7 @@ QQuaternion QQuaternion::fromAxisAndAngle
     \sa nlerp()
 */
 QQuaternion QQuaternion::slerp
-    (const QQuaternion& q1, const QQuaternion& q2, qreal t)
+    (const QQuaternion& q1, const QQuaternion& q2, float t)
 {
     // Handle the easy cases first.
     if (t <= 0.0f)
@@ -505,7 +505,7 @@ QQuaternion QQuaternion::slerp
 
     // Determine the angle between the two quaternions.
     QQuaternion q2b;
-    qreal dot;
+    float dot;
     dot = q1.xp * q2.xp + q1.yp * q2.yp + q1.zp * q2.zp + q1.wp * q2.wp;
     if (dot >= 0.0f) {
         q2b = q2;
@@ -516,14 +516,14 @@ QQuaternion QQuaternion::slerp
 
     // Get the scale factors.  If they are too small,
     // then revert to simple linear interpolation.
-    qreal factor1 = 1.0f - t;
-    qreal factor2 = t;
+    float factor1 = 1.0f - t;
+    float factor2 = t;
     if ((1.0f - dot) > 0.0000001) {
-        qreal angle = qreal(qAcos(dot));
-        qreal sinOfAngle = qreal(qSin(angle));
+        float angle = float(qAcos(dot));
+        float sinOfAngle = float(qSin(angle));
         if (sinOfAngle > 0.0000001) {
-            factor1 = qreal(qSin((1.0f - t) * angle)) / sinOfAngle;
-            factor2 = qreal(qSin(t * angle)) / sinOfAngle;
+            factor1 = float(qSin((1.0f - t) * angle)) / sinOfAngle;
+            factor2 = float(qSin(t * angle)) / sinOfAngle;
         }
     }
 
@@ -547,7 +547,7 @@ QQuaternion QQuaternion::slerp
     \sa slerp()
 */
 QQuaternion QQuaternion::nlerp
-    (const QQuaternion& q1, const QQuaternion& q2, qreal t)
+    (const QQuaternion& q1, const QQuaternion& q2, float t)
 {
     // Handle the easy cases first.
     if (t <= 0.0f)
@@ -557,7 +557,7 @@ QQuaternion QQuaternion::nlerp
 
     // Determine the angle between the two quaternions.
     QQuaternion q2b;
-    qreal dot;
+    float dot;
     dot = q1.xp * q2.xp + q1.yp * q2.yp + q1.zp * q2.zp + q1.wp * q2.wp;
     if (dot >= 0.0f)
         q2b = q2;
@@ -602,8 +602,8 @@ QDebug operator<<(QDebug dbg, const QQuaternion &q)
 
 QDataStream &operator<<(QDataStream &stream, const QQuaternion &quaternion)
 {
-    stream << double(quaternion.scalar()) << double(quaternion.x())
-           << double(quaternion.y()) << double(quaternion.z());
+    stream << quaternion.scalar() << quaternion.x()
+           << quaternion.y() << quaternion.z();
     return stream;
 }
 
@@ -619,15 +619,15 @@ QDataStream &operator<<(QDataStream &stream, const QQuaternion &quaternion)
 
 QDataStream &operator>>(QDataStream &stream, QQuaternion &quaternion)
 {
-    double scalar, x, y, z;
+    float scalar, x, y, z;
     stream >> scalar;
     stream >> x;
     stream >> y;
     stream >> z;
-    quaternion.setScalar(qreal(scalar));
-    quaternion.setX(qreal(x));
-    quaternion.setY(qreal(y));
-    quaternion.setZ(qreal(z));
+    quaternion.setScalar(scalar);
+    quaternion.setX(x);
+    quaternion.setY(y);
+    quaternion.setZ(z);
     return stream;
 }