Allow specify distance to plane for QTransform

The default camera to plane distance is 1024, when rotating a big image
along the x or y axis, some areas of the screen may move above the
camera, causing the rotation to fail. A new rotation interface has been
added to allow users to specify the distance from the camera to the
plane themselves when rotating the QImage. Also, this support has been
added to QMatrix4x4::projectedRotate.

[ChangeLog][QtGui][QTransform] Added overloads to rotate() and
rotateRadians() that allow specifying of the distance to the rotation
plane.

Fixes: QTBUG-105088
Change-Id: I81f629916ddd9b6ab84e0282191e4284a88a85f5
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

1 files changed, 28 insertions, 11 deletions

diff --git a/src/gui/math3d/qmatrix4x4.cpp b/src/gui/math3d/qmatrix4x4.cpp
index 0e5db480d7..39625cdfb4 100644
--- a/src/gui/math3d/qmatrix4x4.cpp
+++ b/src/gui/math3d/qmatrix4x4.cpp
@@ -1164,12 +1164,15 @@ void QMatrix4x4::rotate(float angle, float x, float y, float z)
 /*!
     \internal
 */
-void QMatrix4x4::projectedRotate(float angle, float x, float y, float z)
+void QMatrix4x4::projectedRotate(float angle, float x, float y, float z, float distanceToPlane)
 {
     // Used by QGraphicsRotation::applyTo() to perform a rotation
     // and projection back to 2D in a single step.
+    if (qIsNull(distanceToPlane))
+        return rotate(angle, x, y, z);
     if (angle == 0.0f)
         return;
+
     float c, s;
     if (angle == 90.0f || angle == -270.0f) {
         s = 1.0f;
@@ -1185,6 +1188,8 @@ void QMatrix4x4::projectedRotate(float angle, float x, float y, float z)
         c = std::cos(a);
         s = std::sin(a);
     }
+
+    const qreal d = 1.0 / distanceToPlane;
     if (x == 0.0f) {
         if (y == 0.0f) {
             if (z != 0.0f) {
@@ -1208,10 +1213,11 @@ void QMatrix4x4::projectedRotate(float angle, float x, float y, float z)
             // Rotate around the Y axis.
             if (y < 0)
                 s = -s;
-            m[0][0] = m[0][0] * c + m[3][0] * s * inv_dist_to_plane;
-            m[0][1] = m[0][1] * c + m[3][1] * s * inv_dist_to_plane;
-            m[0][2] = m[0][2] * c + m[3][2] * s * inv_dist_to_plane;
-            m[0][3] = m[0][3] * c + m[3][3] * s * inv_dist_to_plane;
+            s *= d;
+            m[0][0] = m[0][0] * c + m[3][0] * s;
+            m[0][1] = m[0][1] * c + m[3][1] * s;
+            m[0][2] = m[0][2] * c + m[3][2] * s;
+            m[0][3] = m[0][3] * c + m[3][3] * s;
             flagBits = General;
             return;
         }
@@ -1219,10 +1225,11 @@ void QMatrix4x4::projectedRotate(float angle, float x, float y, float z)
         // Rotate around the X axis.
         if (x < 0)
             s = -s;
-        m[1][0] = m[1][0] * c - m[3][0] * s * inv_dist_to_plane;
-        m[1][1] = m[1][1] * c - m[3][1] * s * inv_dist_to_plane;
-        m[1][2] = m[1][2] * c - m[3][2] * s * inv_dist_to_plane;
-        m[1][3] = m[1][3] * c - m[3][3] * s * inv_dist_to_plane;
+        s *= d;
+        m[1][0] = m[1][0] * c - m[3][0] * s;
+        m[1][1] = m[1][1] * c - m[3][1] * s;
+        m[1][2] = m[1][2] * c - m[3][2] * s;
+        m[1][3] = m[1][3] * c - m[3][3] * s;
         flagBits = General;
         return;
     }
@@ -1249,14 +1256,24 @@ void QMatrix4x4::projectedRotate(float angle, float x, float y, float z)
     rot.m[1][2] = 0.0f;
     rot.m[2][2] = 1.0f;
     rot.m[3][2] = 0.0f;
-    rot.m[0][3] = (x * z * ic - y * s) * -inv_dist_to_plane;
-    rot.m[1][3] = (y * z * ic + x * s) * -inv_dist_to_plane;
+    rot.m[0][3] = (x * z * ic - y * s) * -d;
+    rot.m[1][3] = (y * z * ic + x * s) * -d;
     rot.m[2][3] = 0.0f;
     rot.m[3][3] = 1.0f;
     rot.flagBits = General;
     *this *= rot;
 }
 
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
+/*!
+    \internal
+*/
+void QMatrix4x4::projectedRotate(float angle, float x, float y, float z)
+{
+    projectedRotate(angle, x, y, z, 1024.0);
+}
+#endif
+
 /*!
     \fn int QMatrix4x4::flags() const
     \internal