Rendering rtl-sdr I/Q data to the GL canvas

src/AppFrame.cpp

@@ -23,7 +23,7 @@ wxEND_EVENT_TABLE()
 AppFrame::AppFrame() :
         wxFrame(NULL, wxID_ANY, wxT("CubicSDR")) {
 
-    new TestGLCanvas(this, NULL);
+    canvas = new TestGLCanvas(this, NULL);
 
 //    SetIcon(wxICON(sample));
 
@@ -57,9 +57,11 @@ void AppFrame::OnNewWindow(wxCommandEvent& WXUNUSED(event)) {
 }
 
 void AppFrame::OnEventInput(wxThreadEvent& event) {
-    std::vector<unsigned char> *new_buffer = event.GetPayload<std::vector<unsigned char> *>();
+    std::vector<signed char> *new_buffer = event.GetPayload<std::vector<signed char> *>();
 
-    std::cout << "Got IQ buffer, length: " << new_buffer->size() << std::endl;
+//    std::cout << "Got IQ buffer, length: " << new_buffer->size() << std::endl;
+
+    canvas->setData(new_buffer);
 
     delete new_buffer;
 }

src/AppFrame.h

@@ -14,5 +14,7 @@ private:
     void OnNewWindow(wxCommandEvent& event);
     void OnIdle(wxIdleEvent& event);
 
+    TestGLCanvas *canvas;
+
 wxDECLARE_EVENT_TABLE();
 };

src/IQBufferThread.cpp

@@ -1,7 +1,6 @@
 #include "IQBufferThread.h"
 #include <cstring>
 
-
 #include "wx/wxprec.h"
 
 #ifndef WX_PRECOMP
@@ -12,8 +11,6 @@
 #error "OpenGL required: set wxUSE_GLCANVAS to 1 and rebuild the library"
 #endif
 
-
-
 #define BUF_SIZE (16 * 32 * 512)
 
 IQBufferThread::IQBufferThread(wxApp *app) :
@@ -24,7 +21,7 @@ IQBufferThread::~IQBufferThread() {
 
 }
 wxThread::ExitCode IQBufferThread::Entry() {
-    unsigned char *buf = (unsigned char*) malloc(BUF_SIZE);
+    signed char *buf = (signed char*) malloc(BUF_SIZE);
 
     int n_read;
     int i = 0;
@@ -40,7 +37,7 @@ wxThread::ExitCode IQBufferThread::Entry() {
 //                iq_buffer.pop();
 //                delete old_buffer;
 //            }
-            std::cout << "#";
+//            std::cout << "#";
 //        }
         this->Sleep(100);
     }

src/IQBufferThread.h

@@ -10,19 +10,17 @@
 #include "SDRThread.h"
 #include <queue>
 
-
 class IQBufferThread: public wxThread {
 public:
 
     IQBufferThread(wxApp *app);
     ~IQBufferThread();
 
-    void OnEventInput(wxEvent& event)
-    {
-       std::cout << "event !" << std::endl;
+    void OnEventInput(wxEvent& event) {
+        std::cout << "event !" << std::endl;
     }
 protected:
     virtual ExitCode Entry();
     wxApp *handler;
-    std::queue<std::vector<unsigned char> *> iq_buffer;
+    std::queue<std::vector<signed char> *> iq_buffer;
 };

src/PrimaryGLContext.cpp

@@ -59,23 +59,45 @@ PrimaryGLContext::PrimaryGLContext(wxGLCanvas *canvas) :
     CheckGLError();
 }
 
-void PrimaryGLContext::PlotIQ() {
+void PrimaryGLContext::PlotIQ(std::vector<float> &i_points, std::vector<float> &q_points) {
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();
 
-    glBegin(GL_LINE_STRIP);
-    glColor3f(1.0f, 1.0f, 1.0f);
-    glVertex3f(-1.0f, -0.5f, 0.0f);
-    glVertex3f(1.0f, -0.5f, 0.0f);
-    glEnd();
+    glPushMatrix();
+    glTranslatef(0.0f, 0.5f, 0.0f);
+    if (q_points.size()) {
+        glScalef(10.0f, 1.0f, 1.0f);
+        glEnableClientState(GL_VERTEX_ARRAY);
+        glVertexPointer(2, GL_FLOAT, 0, &q_points[0]);
+        glDrawArrays(GL_LINE_STRIP, 0, q_points.size() / 2);
+        glDisableClientState(GL_VERTEX_ARRAY);
+    } else {
+        glBegin(GL_LINE_STRIP);
+        glColor3f(1.0f, 1.0f, 1.0f);
+        glVertex3f(-1.0f, 0.0f, 0.0f);
+        glVertex3f(1.0f, 0.0f, 0.0f);
+        glEnd();
+    }
+    glPopMatrix();
 
-    glBegin(GL_LINE_STRIP);
-    glColor3f(1.0f, 1.0f, 1.0f);
-    glVertex3f(-1.0f, 0.5f, 0.0f);
-    glVertex3f(1.0f, 0.5f, 0.0f);
-    glEnd();
+    glPushMatrix();
+    glTranslatef(0.0f, -0.5f, 0.0f);
+    if (i_points.size()) {
+        glScalef(10.0f, 1.0f, 1.0f);
+        glEnableClientState(GL_VERTEX_ARRAY);
+        glVertexPointer(2, GL_FLOAT, 0, &i_points[0]);
+        glDrawArrays(GL_LINE_STRIP, 0, i_points.size() / 2);
+        glDisableClientState(GL_VERTEX_ARRAY);
+    } else {
+        glBegin(GL_LINE_STRIP);
+        glColor3f(1.0f, 1.0f, 1.0f);
+        glVertex3f(-1.0f, 0.0f, 0.0f);
+        glVertex3f(1.0f, 0.0f, 0.0f);
+        glEnd();
+    }
+    glPopMatrix();
 
     glFlush();
 
@@ -84,6 +106,7 @@ void PrimaryGLContext::PlotIQ() {
 
 wxBEGIN_EVENT_TABLE(TestGLCanvas, wxGLCanvas) EVT_PAINT(TestGLCanvas::OnPaint)
 EVT_KEY_DOWN(TestGLCanvas::OnKeyDown)
+EVT_IDLE(TestGLCanvas::OnIdle)
 wxEND_EVENT_TABLE()
 
 TestGLCanvas::TestGLCanvas(wxWindow *parent, int *attribList) :
@@ -99,7 +122,7 @@ void TestGLCanvas::OnPaint(wxPaintEvent& WXUNUSED(event)) {
     PrimaryGLContext& canvas = wxGetApp().GetContext(this);
     glViewport(0, 0, ClientSize.x, ClientSize.y);
 
-    canvas.PlotIQ();
+    canvas.PlotIQ(i_points, q_points);
 
     SwapBuffers();
 }
@@ -124,3 +147,24 @@ void TestGLCanvas::OnKeyDown(wxKeyEvent& event) {
     }
 }
 
+void TestGLCanvas::setData(std::vector<signed char> *data) {
+    if (data && data->size()) {
+        if (i_points.size() < data->size()) {
+            i_points.resize(data->size());
+        }
+        if (q_points.size() < data->size()) {
+            q_points.resize(data->size());
+        }
+
+        for (int i = 0, iMax = data->size() / 2; i < iMax; i++) {
+            i_points[i * 2 + 1] = (float) (*data)[i * 2] / 127.0f;
+            q_points[i * 2 + 1] = (float) (*data)[i * 2 + 1] / 127.0f;
+            i_points[i * 2] = q_points[i * 2] = 2.0f * ((float) i / (float) iMax) - 1.0f;
+        }
+    }
+}
+
+void TestGLCanvas::OnIdle(wxIdleEvent &event) {
+    Refresh(false);
+}
+;

src/PrimaryGLContext.h

@@ -3,12 +3,14 @@
 #include "wx/glcanvas.h"
 #include "wx/timer.h"
 
+#include <vector>
+
 class PrimaryGLContext : public wxGLContext
 {
 public:
     PrimaryGLContext(wxGLCanvas *canvas);
 
-    void PlotIQ();
+    void PlotIQ(std::vector<float> &i_points, std::vector<float> &q_points);
 
 private:
     // textures for the cube faces
@@ -20,9 +22,16 @@ class TestGLCanvas : public wxGLCanvas
 public:
     TestGLCanvas(wxWindow *parent, int *attribList = NULL);
 
+    void setData(std::vector<signed char> *data);
+
+    std::vector<float> i_points;
+    std::vector<float> q_points;
+
 private:
     void OnPaint(wxPaintEvent& event);
     void OnKeyDown(wxKeyEvent& event);
 
+    void OnIdle(wxIdleEvent &event);
+
     wxDECLARE_EVENT_TABLE();
 };

src/SDRThread.cpp

@@ -3,7 +3,6 @@
 
 #define BUF_SIZE (16 * 32 * 512)
 
-
 //wxDEFINE_EVENT(wxEVT_COMMAND_SDRThread_INPUT, wxThreadEvent);
 
 SDRThread::SDRThread(AppFrame *frame) :
@@ -91,6 +90,8 @@ wxThread::ExitCode SDRThread::Entry() {
     rtlsdr_open(&dev, 0);
     rtlsdr_set_sample_rate(dev, 2500000);
     rtlsdr_set_center_freq(dev, 105700000);
+    rtlsdr_set_agc_mode(dev, 1);
+    rtlsdr_set_offset_tuning(dev, 1);
     rtlsdr_reset_buffer(dev);
 
     int n_read;
@@ -100,7 +101,11 @@ wxThread::ExitCode SDRThread::Entry() {
 
         rtlsdr_read_sync(dev, buf, BUF_SIZE, &n_read);
         if (!TestDestroy()) {
-            std::vector<unsigned char> *new_buffer = new std::vector<unsigned char>(buf, buf + n_read);
+            std::vector<signed char> *new_buffer = new std::vector<signed char>();
+
+            for (int i = 0; i < n_read; i++) {
+                new_buffer->push_back(buf[i] - 127);
+            }
 
             wxThreadEvent event(wxEVT_THREAD, EVENT_SDR_INPUT);
             event.SetPayload(new_buffer);