OpenGL modernization: compile and link basic shaders

CMakeLists.txt

@@ -117,7 +117,8 @@ set(sdrbase_SOURCES
 	sdrbase/gui/colormapper.cpp
 	sdrbase/gui/glscope.cpp
 	sdrbase/gui/glscopegui.cpp
-	sdrbase/gui/glspectrum.cpp
+	sdrbase/gui/glshadersources.cpp
+    sdrbase/gui/glspectrum.cpp
 	sdrbase/gui/glspectrumgui.cpp
 	sdrbase/gui/indicator.cpp
 	sdrbase/gui/pluginsdialog.cpp
@@ -199,7 +200,8 @@ set(sdrbase_HEADERS
 	include/gui/colormapper.h
 	include/gui/glscope.h
 	include/gui/glscopegui.h
-	include/gui/glspectrum.h
+	include/gui/glshadersources.h
+    include/gui/glspectrum.h
 	include/gui/glspectrumgui.h
 	include/gui/indicator.h
 	include/gui/physicalunit.h

include/gui/glshadersources.h

@@ -23,13 +23,11 @@
 class GLShaderSources
 {
 public:
-	static const QString& getVertexShaderSourceSimple();
-	static const QString& getFragmentShaderSourceColored();
+	static const QString& getVertexShaderSourceSimple() { return m_vertexShaderSourceSimple; }
+	static const QString& getFragmentShaderSourceColored() { return m_fragmentShaderSourceColored; }
 private:
 	static const QString m_vertexShaderSourceSimple;
 	static const QString m_fragmentShaderSourceColored;
 };
 
-
-
 #endif /* INCLUDE_GUI_GLSHADERSOURCES_H_ */

include/gui/glspectrum.h

@@ -21,11 +21,15 @@
 #include <QGLWidget>
 #include <QTimer>
 #include <QMutex>
+#include <QOpenGLBuffer>
+#include <QOpenGLVertexArrayObject>
 #include "dsp/dsptypes.h"
 #include "gui/scaleengine.h"
 #include "dsp/channelmarker.h"
 #include "util/export.h"
 
+class QOpenGLShaderProgram;
+
 class SDRANGEL_API GLSpectrum : public QGLWidget {
 	Q_OBJECT
 
@@ -150,6 +154,12 @@ private:
 
 	bool m_displayChanged;
 
+	QOpenGLVertexArrayObject m_vao;
+	QOpenGLBuffer m_vbo;
+	QOpenGLShaderProgram *m_program;
+	int m_matrixLoc;
+	int m_colorLoc;
+
 	void updateWaterfall(const std::vector<Real>& spectrum);
 	void updateHistogram(const std::vector<Real>& spectrum);
 
@@ -167,6 +177,8 @@ private:
 	void enterEvent(QEvent* event);
 	void leaveEvent(QEvent* event);
 
+	void cleanup();
+
 private slots:
 	void tick();
 	void channelMarkerChanged();

sdrbase/gui/glshadersources.cpp

@@ -18,16 +18,14 @@
 #include "gui/glshadersources.h"
 
 const QString GLShaderSources::m_vertexShaderSourceSimple = QString(
-	    "#version 150\n"
 		"uniform mat4 uMatrix;\n"
-		"in vec4 vertex\n"
+		"attribute vec4 vertex;\n"
 		"void main() {\n"
 		"    gl_Position = uMatrix * vertex;\n"
 		"}\n"
 		);
 
 const QString GLShaderSources::m_fragmentShaderSourceColored = QString(
-	    "#version 150\n"
 		"uniform mediump vec4 uColour;\n"
 		"void main() {\n"
 		"    gl_FragColor = uColour;\n"

sdrbase/gui/glspectrum.cpp

@@ -20,7 +20,9 @@
 #endif
 
 #include <QMouseEvent>
+#include <QOpenGLShaderProgram>
 #include "gui/glspectrum.h"
+#include "gui/glshadersources.h"
 
 #include <QDebug>
 
@@ -58,7 +60,8 @@ GLSpectrum::GLSpectrum(QWidget* parent) :
 	m_histogramHoldoff(NULL),
 	m_histogramTextureAllocated(false),
 	m_displayHistogram(true),
-	m_displayChanged(false)
+	m_displayChanged(false),
+	m_program(0)
 {
 	setAutoFillBackground(false);
 	setAttribute(Qt::WA_OpaquePaintEvent, true);
@@ -110,6 +113,12 @@ GLSpectrum::GLSpectrum(QWidget* parent) :
 	m_frequencyScale.setFont(font());
 	m_frequencyScale.setOrientation(Qt::Horizontal);
 
+	m_vao.create();
+	QOpenGLVertexArrayObject::Binder vaoBinder(&m_vao);
+	m_vbo.create();
+	m_vbo.bind();
+	// TODO: allocate VBO
+
 	connect(&m_timer, SIGNAL(timeout()), this, SLOT(tick()));
 	m_timer.start(50);
 }
@@ -154,6 +163,10 @@ GLSpectrum::~GLSpectrum()
 		deleteTexture(m_frequencyTexture);
 		m_frequencyTextureAllocated = false;
 	}
+
+    makeCurrent(); // TODO: move to cleanup() wnem inheriting from QOpenGLWidget
+    m_vbo.destroy();
+    doneCurrent();
 }
 
 void GLSpectrum::setCenterFrequency(quint64 frequency)
@@ -484,7 +497,18 @@ void GLSpectrum::updateHistogram(const std::vector<Real>& spectrum)
 
 void GLSpectrum::initializeGL()
 {
-	 glDisable(GL_DEPTH_TEST);
+	//connect(context(), &QOpenGLContext::aboutToBeDestroyed, this, &GLSpectrum::cleanup); // TODO: when migrating to QOpenGLWidget
+	glDisable(GL_DEPTH_TEST);
+
+	m_program = new QOpenGLShaderProgram;
+	m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, GLShaderSources::getVertexShaderSourceSimple());
+	m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, GLShaderSources::getFragmentShaderSourceColored());
+	m_program->bindAttributeLocation("vertex", 0);
+	m_program->link();
+	m_program->bind();
+	m_matrixLoc = m_program->uniformLocation("uMatrix");
+	m_colorLoc = m_program->uniformLocation("uColor");
+	m_program->release();
 }
 
 void GLSpectrum::resizeGL(int width, int height)
@@ -2041,3 +2065,14 @@ void GLSpectrum::connectTimer(const QTimer& timer)
 	connect(&timer, SIGNAL(timeout()), this, SLOT(tick()));
 	m_timer.stop();
 }
+
+void GLSpectrum::cleanup()
+{
+	makeCurrent();
+    if (m_program) {
+    	delete m_program;
+    	m_program = 0;
+    }
+    m_program = 0;
+    doneCurrent();
+}