Implement API function for rendering volume slice to an image.

Change-Id: Iea18967c3b525a8d4507a06e6541c85ed3abb470
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>

9 files changed, 204 insertions, 19 deletions

diff --git a/examples/datavisualization/volumetric/main.cpp b/examples/datavisualization/volumetric/main.cpp
index 66f62779..5a90070e 100644
--- a/examples/datavisualization/volumetric/main.cpp
+++ b/examples/datavisualization/volumetric/main.cpp
@@ -106,22 +106,42 @@ int main(int argc, char **argv)
     colorTableCheckBox->setText(QStringLiteral("Alternate color table"));
     colorTableCheckBox->setChecked(false);
 
+    QLabel *sliceImageXLabel = new QLabel(widget);
+    QLabel *sliceImageYLabel = new QLabel(widget);
+    QLabel *sliceImageZLabel = new QLabel(widget);
+    sliceImageXLabel->setMinimumSize(QSize(200, 100));
+    sliceImageYLabel->setMinimumSize(QSize(200, 200));
+    sliceImageZLabel->setMinimumSize(QSize(200, 100));
+    sliceImageXLabel->setMaximumSize(QSize(200, 100));
+    sliceImageYLabel->setMaximumSize(QSize(200, 200));
+    sliceImageZLabel->setMaximumSize(QSize(200, 100));
+    sliceImageXLabel->setFrameShape(QFrame::Box);
+    sliceImageYLabel->setFrameShape(QFrame::Box);
+    sliceImageZLabel->setFrameShape(QFrame::Box);
+    sliceImageXLabel->setScaledContents(true);
+    sliceImageYLabel->setScaledContents(true);
+    sliceImageZLabel->setScaledContents(true);
+
     vLayout->addWidget(fpsCheckBox);
     vLayout->addWidget(fpsLabel);
     vLayout->addWidget(textureDetailGroupBox);
     vLayout->addWidget(colorTableCheckBox);
     vLayout->addWidget(sliceXCheckBox);
     vLayout->addWidget(sliceXSlider);
+    vLayout->addWidget(sliceImageXLabel);
     vLayout->addWidget(sliceYCheckBox);
     vLayout->addWidget(sliceYSlider);
+    vLayout->addWidget(sliceImageYLabel);
     vLayout->addWidget(sliceZCheckBox);
-    vLayout->addWidget(sliceZSlider, 1, Qt::AlignTop);
+    vLayout->addWidget(sliceZSlider);
+    vLayout->addWidget(sliceImageZLabel, 1, Qt::AlignTop);
 
     VolumetricModifier *modifier = new VolumetricModifier(graph);
     modifier->setFpsLabel(fpsLabel);
     modifier->setMediumDetailRB(mediumDetailRB);
     modifier->setHighDetailRB(highDetailRB);
     modifier->setSliceSliders(sliceXSlider, sliceYSlider, sliceZSlider);
+    modifier->setSliceLabels(sliceImageXLabel, sliceImageYLabel, sliceImageZLabel);
 
     QObject::connect(fpsCheckBox, &QCheckBox::stateChanged, modifier,
                      &VolumetricModifier::setFpsMeasurement);
diff --git a/examples/datavisualization/volumetric/volumetric.cpp b/examples/datavisualization/volumetric/volumetric.cpp
index b4ea769c..a553ccf8 100644
--- a/examples/datavisualization/volumetric/volumetric.cpp
+++ b/examples/datavisualization/volumetric/volumetric.cpp
@@ -51,7 +51,10 @@ VolumetricModifier::VolumetricModifier(Q3DScatter *scatter)
       m_highDetailIndex(0),
       m_sliceSliderX(0),
       m_sliceSliderY(0),
-      m_sliceSliderZ(0)
+      m_sliceSliderZ(0),
+      m_sliceLabelX(0),
+      m_sliceLabelY(0),
+      m_sliceLabelZ(0)
 {
     m_graph->activeTheme()->setType(Q3DTheme::ThemeQt);
     m_graph->setShadowQuality(QAbstract3DGraph::ShadowQualityNone);
@@ -95,12 +98,12 @@ VolumetricModifier::VolumetricModifier(Q3DScatter *scatter)
     }
 
     // The alternate color table.
-    // The first visible layer is a thin yellow one, and rest of the volume uses a smooth gradient.
+    // The first visible layer is a thin single color, and rest of the volume uses a smooth gradient.
     for (int i = 1; i < colorTableSize; i++) {
         if (i < cutOffColorIndex)
             m_colorTable2[i] = qRgba(0, 0, 0, 0);
         else if (i < cutOffColorIndex + 4)
-            m_colorTable2[i] = qRgba(255, 255, 0, 255);
+            m_colorTable2[i] = qRgba(75, 150, 0, 255);
         else
             m_colorTable2[i] = qRgba(i, 0, 255 - i, 255);
     }
@@ -108,6 +111,7 @@ VolumetricModifier::VolumetricModifier(Q3DScatter *scatter)
     m_volumeItem->setColorTable(m_colorTable1);
 
     m_graph->addCustomItem(m_volumeItem);
+
     m_timer.start(0);
 #else
     // OpenGL ES2 doesn't support 3D textures, so show a warning label instead
@@ -152,6 +156,17 @@ void VolumetricModifier::setHighDetailRB(QRadioButton *button)
     m_highDetailRB = button;
 }
 
+void VolumetricModifier::setSliceLabels(QLabel *xLabel, QLabel *yLabel, QLabel *zLabel)
+{
+    m_sliceLabelX = xLabel;
+    m_sliceLabelY = yLabel;
+    m_sliceLabelZ = zLabel;
+
+    adjustSliceX(m_sliceSliderX->value());
+    adjustSliceY(m_sliceSliderY->value());
+    adjustSliceZ(m_sliceSliderZ->value());
+}
+
 void VolumetricModifier::sliceX(int enabled)
 {
     if (m_volumeItem)
@@ -173,22 +188,40 @@ void VolumetricModifier::sliceZ(int enabled)
 void VolumetricModifier::adjustSliceX(int value)
 {
     m_sliceIndexX = value / (1024 / m_volumeItem->textureWidth());
-    if (m_volumeItem && m_volumeItem->sliceIndexX() != -1)
-        m_volumeItem->setSliceIndexX(m_sliceIndexX);
+    if (m_sliceIndexX == m_volumeItem->textureWidth())
+        m_sliceIndexX--;
+    if (m_volumeItem) {
+        if (m_volumeItem->sliceIndexX() != -1)
+            m_volumeItem->setSliceIndexX(m_sliceIndexX);
+        m_sliceLabelX->setPixmap(QPixmap::fromImage(
+                                     m_volumeItem->renderSlice(Qt::XAxis, m_sliceIndexX)));
+    }
 }
 
 void VolumetricModifier::adjustSliceY(int value)
 {
     m_sliceIndexY = value / (1024 / m_volumeItem->textureHeight());
-    if (m_volumeItem && m_volumeItem->sliceIndexY() != -1)
-        m_volumeItem->setSliceIndexY(m_sliceIndexY);
+    if (m_sliceIndexY == m_volumeItem->textureHeight())
+        m_sliceIndexY--;
+    if (m_volumeItem) {
+        if (m_volumeItem->sliceIndexY() != -1)
+            m_volumeItem->setSliceIndexY(m_sliceIndexY);
+        m_sliceLabelY->setPixmap(QPixmap::fromImage(
+                                     m_volumeItem->renderSlice(Qt::YAxis, m_sliceIndexY)));
+    }
 }
 
 void VolumetricModifier::adjustSliceZ(int value)
 {
     m_sliceIndexZ = value / (1024 / m_volumeItem->textureDepth());
-    if (m_volumeItem && m_volumeItem->sliceIndexZ() != -1)
-        m_volumeItem->setSliceIndexZ(m_sliceIndexZ);
+    if (m_sliceIndexZ == m_volumeItem->textureDepth())
+        m_sliceIndexZ--;
+    if (m_volumeItem)  {
+        if (m_volumeItem->sliceIndexZ() != -1)
+            m_volumeItem->setSliceIndexZ(m_sliceIndexZ);
+        m_sliceLabelZ->setPixmap(QPixmap::fromImage(
+                                     m_volumeItem->renderSlice(Qt::ZAxis, m_sliceIndexZ)));
+    }
 }
 
 void VolumetricModifier::handleZoomLevelChange()
@@ -282,6 +315,11 @@ void VolumetricModifier::changeColorTable(int enabled)
         m_volumeItem->setColorTable(m_colorTable2);
     else
         m_volumeItem->setColorTable(m_colorTable1);
+
+    // Rerender image labels
+    adjustSliceX(m_sliceSliderX->value());
+    adjustSliceY(m_sliceSliderY->value());
+    adjustSliceZ(m_sliceSliderZ->value());
 }
 
 int VolumetricModifier::createVolume(int textureSize, int startIndex, int count,
diff --git a/examples/datavisualization/volumetric/volumetric.h b/examples/datavisualization/volumetric/volumetric.h
index bb7fb3fe..eb8a4172 100644
--- a/examples/datavisualization/volumetric/volumetric.h
+++ b/examples/datavisualization/volumetric/volumetric.h
@@ -40,6 +40,7 @@ public:
     void setFpsLabel(QLabel *fpsLabel);
     void setMediumDetailRB(QRadioButton *button);
     void setHighDetailRB(QRadioButton *button);
+    void setSliceLabels(QLabel *xLabel, QLabel *yLabel, QLabel *zLabel);
 
 public slots:
     void sliceX(int enabled);
@@ -82,6 +83,9 @@ private:
     QSlider *m_sliceSliderZ;
     QVector<QRgb> m_colorTable1;
     QVector<QRgb> m_colorTable2;
+    QLabel *m_sliceLabelX;
+    QLabel *m_sliceLabelY;
+    QLabel *m_sliceLabelZ;
 };
 
 #endif
diff --git a/src/datavisualization/data/qcustom3dvolume.cpp b/src/datavisualization/data/qcustom3dvolume.cpp
index a7bbae9b..cab79ac0 100644
--- a/src/datavisualization/data/qcustom3dvolume.cpp
+++ b/src/datavisualization/data/qcustom3dvolume.cpp
@@ -577,6 +577,86 @@ QImage::Format QCustom3DVolume::textureFormat() const
     return dptrc()->m_textureFormat;
 }
 
+/*!
+ * Renders the slice specified by \a index along \a axis into an image.
+ * The texture format of this object is used.
+ *
+ * \return the rendered image of the slice, or a null image if invalid index is specified.
+ *
+ * \sa textureFormat
+ */
+QImage QCustom3DVolume::renderSlice(Qt::Axis axis, int index)
+{
+    if (index < 0)
+        return QImage();
+
+    int x;
+    int y;
+    if (axis == Qt::XAxis) {
+        if (index >= textureWidth())
+            return QImage();
+        x = textureDepth();
+        y = textureHeight();
+    } else if (axis == Qt::YAxis) {
+        if (index >= textureHeight())
+            return QImage();
+        x = textureWidth();
+        y = textureDepth();
+    } else {
+        if (index >= textureDepth())
+            return QImage();
+        x = textureWidth();
+        y = textureHeight();
+    }
+
+    int padding = 0;
+    int pixelWidth = 4;
+    if (textureFormat() == QImage::Format_Indexed8) {
+        padding = x % 4;
+        pixelWidth = 1;
+    }
+    QVector<uchar> data((x + padding) * y * pixelWidth);
+    int frameSize = textureDataWidth() * textureHeight();
+
+    int dataIndex = 0;
+    if (axis == Qt::XAxis) {
+        for (int i = 0; i < y; i++) {
+            const uchar *p = textureData()->constData()
+                    + (index * pixelWidth) + (textureDataWidth() * i);
+            for (int j = 0; j < x; j++) {
+                data[dataIndex++] = *p;
+                for (int k = 1; k < pixelWidth; k++)
+                    data[dataIndex++] = *(p + k);
+                p += frameSize;
+            }
+        }
+    } else if (axis == Qt::YAxis) {
+        for (int i = 0; i < y; i++) {
+            const uchar *p = textureData()->constData() + (index * textureDataWidth())
+                    + (frameSize * i);
+            for (int j = 0; j < (x * pixelWidth); j++) {
+                data[dataIndex++] = *p;
+                p++;
+            }
+        }
+    } else {
+        for (int i = 0; i < y; i++) {
+            const uchar *p = textureData()->constData() + (index * frameSize)
+                    + (textureDataWidth() * i);
+            for (int j = 0; j < (x * pixelWidth); j++) {
+                data[dataIndex++] = *p;
+                p++;
+            }
+        }
+    }
+
+    QImage image(data.constData(), x, y, x * pixelWidth, textureFormat());
+    image.bits(); // Call bits() to detach the new image from local data
+    if (textureFormat() == QImage::Format_Indexed8)
+        image.setColorTable(colorTable());
+
+    return image;
+}
 
 /*!
  * \internal
@@ -637,9 +717,6 @@ QCustom3DVolumePrivate::QCustom3DVolumePrivate(QCustom3DVolume *q, const QVector
     if (m_textureDepth < 0)
         m_textureDepth = 0;
 
-    if (m_colorTable.size() != 256)
-        m_colorTable.clear();
-
     if (m_textureFormat != QImage::Format_Indexed8)
         m_textureFormat = QImage::Format_ARGB32;
 
diff --git a/src/datavisualization/data/qcustom3dvolume.h b/src/datavisualization/data/qcustom3dvolume.h
index 498922e8..00733d17 100644
--- a/src/datavisualization/data/qcustom3dvolume.h
+++ b/src/datavisualization/data/qcustom3dvolume.h
@@ -80,6 +80,8 @@ public:
     void setTextureFormat(QImage::Format format);
     QImage::Format textureFormat() const;
 
+    QImage renderSlice(Qt::Axis axis, int index);
+
 signals:
     void textureWidthChanged(int value);
     void textureHeightChanged(int value);
diff --git a/src/datavisualization/engine/shaders/texture3dslice.frag b/src/datavisualization/engine/shaders/texture3dslice.frag
index 409ab41d..8870b26d 100644
--- a/src/datavisualization/engine/shaders/texture3dslice.frag
+++ b/src/datavisualization/engine/shaders/texture3dslice.frag
@@ -33,8 +33,8 @@ void main() {
         if (rayDir.z < 0)
             boxBounds.z = -1.0;
         highp vec3 t = (boxBounds - rayStart) * invRayDir;
-        tFar = max(t.x, t.y);
-        tFar = max(tFar, t.z);
+        tFar = min(t.x, t.y);
+        tFar = min(tFar, t.z);
     }
 
     highp vec3 xPoint = vec3(volumeSliceIndices.x, 0, 0);
diff --git a/tests/volumetrictest/main.cpp b/tests/volumetrictest/main.cpp
index a15caf88..e838c43a 100644
--- a/tests/volumetrictest/main.cpp
+++ b/tests/volumetrictest/main.cpp
@@ -77,16 +77,37 @@ int main(int argc, char **argv)
 
     QLabel *fpsLabel = new QLabel(QStringLiteral("Fps: "), widget);
 
+    QLabel *sliceImageXLabel = new QLabel(widget);
+    QLabel *sliceImageYLabel = new QLabel(widget);
+    QLabel *sliceImageZLabel = new QLabel(widget);
+    sliceImageXLabel->setMinimumSize(QSize(200, 100));
+    sliceImageYLabel->setMinimumSize(QSize(200, 200));
+    sliceImageZLabel->setMinimumSize(QSize(200, 100));
+    sliceImageXLabel->setMaximumSize(QSize(200, 100));
+    sliceImageYLabel->setMaximumSize(QSize(200, 200));
+    sliceImageZLabel->setMaximumSize(QSize(200, 100));
+    sliceImageXLabel->setFrameShape(QFrame::Box);
+    sliceImageYLabel->setFrameShape(QFrame::Box);
+    sliceImageZLabel->setFrameShape(QFrame::Box);
+    sliceImageXLabel->setScaledContents(true);
+    sliceImageYLabel->setScaledContents(true);
+    sliceImageZLabel->setScaledContents(true);
+
     vLayout->addWidget(fpsLabel);
     vLayout->addWidget(sliceXCheckBox);
     vLayout->addWidget(sliceXSlider);
+    vLayout->addWidget(sliceImageXLabel);
     vLayout->addWidget(sliceYCheckBox);
     vLayout->addWidget(sliceYSlider);
+    vLayout->addWidget(sliceImageYLabel);
     vLayout->addWidget(sliceZCheckBox);
-    vLayout->addWidget(sliceZSlider, 1, Qt::AlignTop);
+    vLayout->addWidget(sliceZSlider);
+    vLayout->addWidget(sliceImageZLabel, 1, Qt::AlignTop);
+
 
     VolumetricModifier *modifier = new VolumetricModifier(graph);
     modifier->setFpsLabel(fpsLabel);
+    modifier->setSliceLabels(sliceImageXLabel, sliceImageYLabel, sliceImageZLabel);
 
     QObject::connect(sliceXCheckBox, &QCheckBox::stateChanged, modifier,
                      &VolumetricModifier::sliceX);
diff --git a/tests/volumetrictest/volumetrictest.cpp b/tests/volumetrictest/volumetrictest.cpp
index 701cfc04..3485dd24 100644
--- a/tests/volumetrictest/volumetrictest.cpp
+++ b/tests/volumetrictest/volumetrictest.cpp
@@ -66,6 +66,8 @@ VolumetricModifier::VolumetricModifier(Q3DScatter *scatter)
     m_graph->addCustomItem(m_plainItem);
     //m_graph->setMeasureFps(true);
 
+
+
     QObject::connect(m_graph, &QAbstract3DGraph::currentFpsChanged, this,
                      &VolumetricModifier::handleFpsChange);
 //    QObject::connect(m_graph->scene(), &Q3DScene::viewportChanged, this,
@@ -110,6 +112,9 @@ void VolumetricModifier::adjustSliceX(int value)
         m_volumeItem->setSliceIndexX(m_sliceIndexX);
         m_volumeItem2->setSliceIndexX(m_sliceIndexX);
     }
+    m_sliceLabelX->setPixmap(QPixmap::fromImage(
+                                 m_volumeItem2->renderSlice(Qt::XAxis, m_sliceIndexX)));
+
 }
 
 void VolumetricModifier::adjustSliceY(int value)
@@ -122,6 +127,8 @@ void VolumetricModifier::adjustSliceY(int value)
         m_volumeItem->setSliceIndexY(m_sliceIndexY);
         m_volumeItem2->setSliceIndexY(m_sliceIndexY);
     }
+    m_sliceLabelY->setPixmap(QPixmap::fromImage(
+                                 m_volumeItem2->renderSlice(Qt::YAxis, m_sliceIndexY)));
 }
 
 void VolumetricModifier::adjustSliceZ(int value)
@@ -134,6 +141,8 @@ void VolumetricModifier::adjustSliceZ(int value)
         m_volumeItem->setSliceIndexZ(m_sliceIndexZ);
         m_volumeItem2->setSliceIndexZ(m_sliceIndexZ);
     }
+    m_sliceLabelZ->setPixmap(QPixmap::fromImage(
+                                 m_volumeItem2->renderSlice(Qt::ZAxis, m_sliceIndexZ)));
 }
 
 void VolumetricModifier::handleFpsChange()
@@ -208,8 +217,8 @@ void VolumetricModifier::createVolume()
     uchar *p = data;
 
     // Change one picture using subtexture replacement
-//    QImage flipped = logo.mirrored();
-//    m_volumeItem->setSubTextureData(101, flipped);
+    QImage flipped = logo.mirrored();
+    m_volumeItem->setSubTextureData(100, flipped);
 
     // Clean up the two extra pixels
     p = data + width - 1;
@@ -337,7 +346,7 @@ void VolumetricModifier::createAnotherVolume()
 
     // Change one picture using subtexture replacement
     QImage flipped = logo.mirrored();
-    m_volumeItem2->setSubTextureData(101, flipped);
+    m_volumeItem2->setSubTextureData(100, flipped);
 }
 
 void VolumetricModifier::createYetAnotherVolume()
@@ -485,3 +494,13 @@ void VolumetricModifier::createYetAnotherVolume()
 
 }
 
+void VolumetricModifier::setSliceLabels(QLabel *xLabel, QLabel *yLabel, QLabel *zLabel)
+{
+    m_sliceLabelX = xLabel;
+    m_sliceLabelY = yLabel;
+    m_sliceLabelZ = zLabel;
+
+    adjustSliceX(512);
+    adjustSliceY(512);
+    adjustSliceZ(512);
+}
diff --git a/tests/volumetrictest/volumetrictest.h b/tests/volumetrictest/volumetrictest.h
index 40d88192..f21fd528 100644
--- a/tests/volumetrictest/volumetrictest.h
+++ b/tests/volumetrictest/volumetrictest.h
@@ -35,6 +35,7 @@ public:
     ~VolumetricModifier();
 
     void setFpsLabel(QLabel *fpsLabel);
+    void setSliceLabels(QLabel *xLabel, QLabel *yLabel, QLabel *zLabel);
 
 public slots:
     void sliceX(int enabled);
@@ -59,6 +60,9 @@ private:
     int m_sliceIndexY;
     int m_sliceIndexZ;
     QLabel *m_fpsLabel;
+    QLabel *m_sliceLabelX;
+    QLabel *m_sliceLabelY;
+    QLabel *m_sliceLabelZ;
 };
 
 #endif