Avoid using huge floating point values in the renderer.

We pretransform vertices relative to their batch root and upload these
using single-precision floats. If the offsets are huge then the
floating point numbers start to get unstable and we get rendering
artifacts as a result. This typically happens for lists/tables with
huge models.

Task-number: QTBUG-34312
Change-Id: I2516f2b4fa93f44a1288659d05458fb1af0df943
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

3 files changed, 112 insertions, 0 deletions

diff --git a/tests/auto/quick/scenegraph/data/render_OutOfFloatRange.qml b/tests/auto/quick/scenegraph/data/render_OutOfFloatRange.qml
new file mode 100644
index 0000000000..60caa4d561
--- /dev/null
+++ b/tests/auto/quick/scenegraph/data/render_OutOfFloatRange.qml
@@ -0,0 +1,108 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.2
+
+/*
+    The test verifies that batching does not interfere with overlapping
+    regions.
+
+    #samples: 8
+                 PixelPos     R    G    B    Error-tolerance
+    #base:        10  10     1.0  0.0  0.0        0.0
+    #base:        10 110     1.0  0.0  0.0        0.0
+    #base:        10  11     0.0  0.0  1.0        0.0
+    #base:        10 111     0.0  0.0  1.0        0.0
+
+    #final:       10  10     1.0  0.0  0.0        0.05
+    #final:       10 110     1.0  0.0  0.0        0.05
+    #final:       10  11     0.0  0.0  1.0        0.05
+    #final:       10 111     0.0  0.0  1.0        0.05
+*/
+
+RenderTestBase
+{
+    id: root
+    property real offset: 0;
+    property real farAway: 10000000;
+
+    Item {
+        y: -root.offset + 10
+        x: 10
+        Repeater {
+            model: 200
+            Rectangle {
+                x: index % 100
+                y: root.offset + (index < 100 ? 0 : 1);
+                width: 1
+                height: 1
+                color: index < 100 ? "red" : "blue"
+                antialiasing: true;
+            }
+        }
+    }
+
+    Item {
+        y: -root.offset + 110
+        x: 10
+        Item {
+            y: root.offset
+
+            Repeater {
+                model: 200
+                Rectangle {
+                    x: index % 100
+                    y: (index < 100 ? 0 : 1);
+                    width: 1
+                    height: 1
+                    color: index < 100 ? "red" : "blue"
+                    antialiasing: true;
+                }
+            }
+        }
+    }
+
+    onEnterFinalStage: {
+        root.offset = root.farAway;
+        root.finalStageComplete = true;
+    }
+
+}
diff --git a/tests/auto/quick/scenegraph/scenegraph.pro b/tests/auto/quick/scenegraph/scenegraph.pro
index 7e7a8eb162..105221b7f4 100644
--- a/tests/auto/quick/scenegraph/scenegraph.pro
+++ b/tests/auto/quick/scenegraph/scenegraph.pro
@@ -9,3 +9,6 @@ macx:CONFIG -= app_bundle
 QT += core-private gui-private qml-private quick-private  testlib
 
 DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
+
+OTHER_FILES += \
+    data/render_OutOfFloatRange.qml
diff --git a/tests/auto/quick/scenegraph/tst_scenegraph.cpp b/tests/auto/quick/scenegraph/tst_scenegraph.cpp
index 656e1c5a58..755cec460d 100644
--- a/tests/auto/quick/scenegraph/tst_scenegraph.cpp
+++ b/tests/auto/quick/scenegraph/tst_scenegraph.cpp
@@ -322,6 +322,7 @@ void tst_SceneGraph::render_data()
           << "data/render_Overlap.qml"
           << "data/render_MovingOverlap.qml"
           << "data/render_BreakOpacityBatch.qml"
+          << "data/render_OutOfFloatRange.qml"
         ;
 
     QRegExp sampleCount("#samples: *(\\d+)");