Implement volume rendering support

New subclass of QCustom3DItem, QCustom3DVolume is provided.
The documentation for the example will be done in a separate commit.

Change-Id: Idb3fdb0654c6bec7606ca012b75852a5a8412397
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>

4 files changed, 117 insertions, 0 deletions

diff --git a/src/datavisualization/utils/shaderhelper.cpp b/src/datavisualization/utils/shaderhelper.cpp
index 7fb237c6..3c3d93ac 100644
--- a/src/datavisualization/utils/shaderhelper.cpp
+++ b/src/datavisualization/utils/shaderhelper.cpp
@@ -93,6 +93,10 @@ void ShaderHelper::initialize()
     m_gradientMinUniform = m_program->uniformLocation("gradMin");
     m_gradientHeightUniform = m_program->uniformLocation("gradHeight");
     m_lightColorUniform = m_program->uniformLocation("lightColor");
+    m_volumeSliceIndices = m_program->uniformLocation("volumeSliceIndices");
+    m_colorIndex = m_program->uniformLocation("colorIndex");
+    m_cameraPositionRelativeToModel = m_program->uniformLocation("cameraPositionRelativeToModel");
+    m_color8Bit = m_program->uniformLocation("color8Bit");
     m_initialized = true;
 }
 
@@ -150,6 +154,11 @@ void ShaderHelper::setUniformValue(GLuint uniform, GLint value)
     m_program->setUniformValue(uniform, value);
 }
 
+void ShaderHelper::setUniformValueArray(GLuint uniform, const QVector4D *values, int count)
+{
+    m_program->setUniformValueArray(uniform, values, count);
+}
+
 GLuint ShaderHelper::MVP()
 {
     if (!m_initialized)
@@ -255,6 +264,34 @@ GLuint ShaderHelper::lightColor()
     return m_lightColorUniform;
 }
 
+GLuint ShaderHelper::volumeSliceIndices()
+{
+    if (!m_initialized)
+        qFatal("Shader not initialized");
+    return m_volumeSliceIndices;
+}
+
+GLuint ShaderHelper::colorIndex()
+{
+    if (!m_initialized)
+        qFatal("Shader not initialized");
+    return m_colorIndex;
+}
+
+GLuint ShaderHelper::cameraPositionRelativeToModel()
+{
+    if (!m_initialized)
+        qFatal("Shader not initialized");
+    return m_cameraPositionRelativeToModel;
+}
+
+GLuint ShaderHelper::color8Bit()
+{
+    if (!m_initialized)
+        qFatal("Shader not initialized");
+    return m_color8Bit;
+}
+
 GLuint ShaderHelper::posAtt()
 {
     if (!m_initialized)
diff --git a/src/datavisualization/utils/shaderhelper_p.h b/src/datavisualization/utils/shaderhelper_p.h
index fdef0dff..67e8a2f3 100644
--- a/src/datavisualization/utils/shaderhelper_p.h
+++ b/src/datavisualization/utils/shaderhelper_p.h
@@ -57,6 +57,7 @@ class ShaderHelper
     void setUniformValue(GLuint uniform, const QMatrix4x4 &value);
     void setUniformValue(GLuint uniform, GLfloat value);
     void setUniformValue(GLuint uniform, GLint value);
+    void setUniformValueArray(GLuint uniform,  const QVector4D *values, int count);
 
     GLuint MVP();
     GLuint view();
@@ -73,6 +74,10 @@ class ShaderHelper
     GLuint gradientMin();
     GLuint gradientHeight();
     GLuint lightColor();
+    GLuint volumeSliceIndices();
+    GLuint colorIndex();
+    GLuint cameraPositionRelativeToModel();
+    GLuint color8Bit();
 
     GLuint posAtt();
     GLuint uvAtt();
@@ -107,6 +112,10 @@ class ShaderHelper
     GLuint m_gradientMinUniform;
     GLuint m_gradientHeightUniform;
     GLuint m_lightColorUniform;
+    GLuint m_volumeSliceIndices;
+    GLuint m_colorIndex;
+    GLuint m_cameraPositionRelativeToModel;
+    GLuint m_color8Bit;
 
     GLboolean m_initialized;
 };
diff --git a/src/datavisualization/utils/texturehelper.cpp b/src/datavisualization/utils/texturehelper.cpp
index 616c1981..5e21b5cd 100644
--- a/src/datavisualization/utils/texturehelper.cpp
+++ b/src/datavisualization/utils/texturehelper.cpp
@@ -21,11 +21,25 @@
 
 #include <QtGui/QImage>
 #include <QtGui/QPainter>
+#include <QtCore/QTime>
 
 QT_BEGIN_NAMESPACE_DATAVISUALIZATION
 
+// Defined in shaderhelper.cpp
+extern void discardDebugMsgs(QtMsgType type, const QMessageLogContext &context, const QString &msg);
+
 TextureHelper::TextureHelper()
 {
+#if !defined(QT_OPENGL_ES_2)
+    // Discard warnings about deprecated functions
+    QtMessageHandler handler = qInstallMessageHandler(discardDebugMsgs);
+
+    m_openGlFunctions_2_1 = new QOpenGLFunctions_2_1;
+    m_openGlFunctions_2_1->initializeOpenGLFunctions();
+
+    // Restore original message handler
+    qInstallMessageHandler(handler);
+#endif
     initializeOpenGLFunctions();
 }
 
@@ -73,8 +87,54 @@ GLuint TextureHelper::create2DTexture(const QImage &image, bool useTrilinearFilt
     if (clampY)
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glBindTexture(GL_TEXTURE_2D, 0);
+
+    return textureId;
+}
+
+#if !defined(QT_OPENGL_ES_2)
+GLuint TextureHelper::create3DTexture(const QVector<uchar> *data, int width, int height, int depth,
+                                      QImage::Format dataFormat)
+{
+    if (!width || !height || !depth)
+        return 0;
+
+    glEnable(GL_TEXTURE_3D);
+
+    GLuint textureId;
+    glGenTextures(1, &textureId);
+    glBindTexture(GL_TEXTURE_3D, textureId);
+    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+
+    GLenum status = glGetError();
+    // glGetError docs advise to call glGetError in loop to clear all error flags
+    while (status)
+        status = glGetError();
+
+    GLint internalFormat = 4;
+    GLint format = GL_BGRA;
+    if (dataFormat == QImage::Format_Indexed8) {
+        internalFormat = 1;
+        format = GL_RED;
+        // Align width to 32bits
+        width = width + width % 4;
+    }
+    m_openGlFunctions_2_1->glTexImage3D(GL_TEXTURE_3D, 0, internalFormat, width, height, depth, 0,
+                                        format, GL_UNSIGNED_BYTE, data->constData());
+
+    status = glGetError();
+    if (status)
+        qWarning() << __FUNCTION__ << "3D texture creation failed:" << status;
+
+    glBindTexture(GL_TEXTURE_3D, 0);
+    glDisable(GL_TEXTURE_3D);
+
     return textureId;
 }
+#endif
 
 GLuint TextureHelper::createCubeMapTexture(const QImage &image, bool useTrilinearFiltering)
 {
diff --git a/src/datavisualization/utils/texturehelper_p.h b/src/datavisualization/utils/texturehelper_p.h
index c20f293c..c1dfe8c9 100644
--- a/src/datavisualization/utils/texturehelper_p.h
+++ b/src/datavisualization/utils/texturehelper_p.h
@@ -32,6 +32,10 @@
 #include "datavisualizationglobal_p.h"
 #include <QtGui/QRgb>
 #include <QtGui/QLinearGradient>
+#if !defined(QT_OPENGL_ES_2)
+// 3D Textures are not supported by ES set
+#  include <QtGui/QOpenGLFunctions_2_1>
+#endif
 
 QT_BEGIN_NAMESPACE_DATAVISUALIZATION
 
@@ -44,6 +48,10 @@ class TextureHelper : protected QOpenGLFunctions
     // Ownership of created texture is transferred to caller
     GLuint create2DTexture(const QImage &image, bool useTrilinearFiltering = false,
                            bool convert = true, bool smoothScale = true, bool clampY = false);
+#if !defined(QT_OPENGL_ES_2)
+    GLuint create3DTexture(const QVector<uchar> *data, int width, int height, int depth,
+                           QImage::Format dataFormat);
+#endif
     GLuint createCubeMapTexture(const QImage &image, bool useTrilinearFiltering = false);
     // Returns selection texture and inserts generated framebuffers to framebuffer parameters
     GLuint createSelectionTexture(const QSize &size, GLuint &frameBuffer, GLuint &depthBuffer);
@@ -61,6 +69,9 @@ class TextureHelper : protected QOpenGLFunctions
     void convertToGLFormatHelper(QImage &dstImage, const QImage &srcImage, GLenum texture_format);
     QRgb qt_gl_convertToGLFormatHelper(QRgb src_pixel, GLenum texture_format);
 
+#if !defined(QT_OPENGL_ES_2)
+    QOpenGLFunctions_2_1 *m_openGlFunctions_2_1;
+#endif
     friend class Bars3DRenderer;
     friend class Surface3DRenderer;
     friend class Scatter3DRenderer;