Merge pull request #3 from saurabhb17/master

secondary files

1 files changed, 1204 insertions, 0 deletions

diff --git a/common/gal/opengl/opengl_gal.cpp b/common/gal/opengl/opengl_gal.cpp
new file mode 100644
index 0000000..945161f
--- /dev/null
+++ b/common/gal/opengl/opengl_gal.cpp
@@ -0,0 +1,1204 @@
+/*
+ * This program source code file is part of KICAD, a free EDA CAD application.
+ *
+ * Copyright (C) 2012 Torsten Hueter, torstenhtr <at> gmx.de
+ * Copyright (C) 2012 Kicad Developers, see change_log.txt for contributors.
+ * Copyright (C) 2013-2016 CERN
+ * @author Maciej Suminski <maciej.suminski@cern.ch>
+ *
+ * Graphics Abstraction Layer (GAL) for OpenGL
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include <gal/opengl/opengl_gal.h>
+#include <gal/definitions.h>
+
+#include <wx/log.h>
+#include <macros.h>
+#ifdef __WXDEBUG__
+#include <profile.h>
+#endif /* __WXDEBUG__ */
+
+#include <limits>
+#include <boost/bind.hpp>
+
+using namespace KIGFX;
+
+static void InitTesselatorCallbacks( GLUtesselator* aTesselator );
+const int glAttributes[] = { WX_GL_RGBA, WX_GL_DOUBLEBUFFER, WX_GL_DEPTH_SIZE, 8, 0 };
+wxGLContext* OPENGL_GAL::glContext = NULL;
+
+OPENGL_GAL::OPENGL_GAL( wxWindow* aParent, wxEvtHandler* aMouseListener,
+                        wxEvtHandler* aPaintListener, const wxString& aName ) :
+    wxGLCanvas( aParent, wxID_ANY, (int*) glAttributes, wxDefaultPosition, wxDefaultSize,
+                wxEXPAND, aName ),
+    mouseListener( aMouseListener ),
+    paintListener( aPaintListener ),
+    cachedManager( true ),
+    nonCachedManager( false ),
+    overlayManager( false )
+{
+    if( glContext == NULL )
+        glContext = new wxGLContext( this );
+
+    // Check if OpenGL requirements are met
+    runTest();
+
+    // Make VBOs use shaders
+    cachedManager.SetShader( shader );
+    nonCachedManager.SetShader( shader );
+    overlayManager.SetShader( shader );
+
+    // Initialize the flags
+    isFramebufferInitialized = false;
+    isGrouping               = false;
+    groupCounter             = 0;
+
+#ifdef RETINA_OPENGL_PATCH
+    SetViewWantsBestResolution( true );
+#endif
+
+    // Connecting the event handlers
+    Connect( wxEVT_PAINT,           wxPaintEventHandler( OPENGL_GAL::onPaint ) );
+
+    // Mouse events are skipped to the parent
+    Connect( wxEVT_MOTION,          wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_LEFT_DOWN,       wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_LEFT_UP,         wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_LEFT_DCLICK,     wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_MIDDLE_DOWN,     wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_MIDDLE_UP,       wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_MIDDLE_DCLICK,   wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_RIGHT_DOWN,      wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_RIGHT_UP,        wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_RIGHT_DCLICK,    wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+    Connect( wxEVT_MOUSEWHEEL,      wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+#ifdef USE_OSX_MAGNIFY_EVENT
+    Connect( wxEVT_MAGNIFY,         wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+#endif
+#if defined _WIN32 || defined _WIN64
+    Connect( wxEVT_ENTER_WINDOW,    wxMouseEventHandler( OPENGL_GAL::skipMouseEvent ) );
+#endif
+
+    SetSize( aParent->GetSize() );
+    screenSize = VECTOR2I( aParent->GetSize() );
+
+    // Grid color settings are different in Cairo and OpenGL
+    SetGridColor( COLOR4D( 0.8, 0.8, 0.8, 0.1 ) );
+
+    // Tesselator initialization
+    tesselator = gluNewTess();
+    InitTesselatorCallbacks( tesselator );
+
+    if( tesselator == NULL )
+        throw std::runtime_error( "Could not create the tesselator" );
+
+    gluTessProperty( tesselator, GLU_TESS_WINDING_RULE, GLU_TESS_WINDING_POSITIVE );
+
+    currentManager = &nonCachedManager;
+}
+
+
+OPENGL_GAL::~OPENGL_GAL()
+{
+    glFlush();
+
+    gluDeleteTess( tesselator );
+    ClearCache();
+}
+
+
+void OPENGL_GAL::BeginDrawing()
+{
+    if( !IsShownOnScreen() )
+        return;
+
+    SetCurrent( *glContext );
+    clientDC = new wxClientDC( this );
+
+#ifdef RETINA_OPENGL_PATCH
+    const float scaleFactor = GetBackingScaleFactor();
+#else
+    const float scaleFactor = 1.0f;
+#endif
+
+    // Set up the view port
+    glMatrixMode( GL_PROJECTION );
+    glLoadIdentity();
+    glViewport( 0, 0, (GLsizei) screenSize.x * scaleFactor, (GLsizei) screenSize.y * scaleFactor );
+
+    // Create the screen transformation
+    glOrtho( 0, (GLint) screenSize.x, 0, (GLsizei) screenSize.y,
+             -depthRange.x, -depthRange.y );
+
+    if( !isFramebufferInitialized )
+    {
+        // Prepare rendering target buffers
+        compositor.Initialize();
+        mainBuffer = compositor.CreateBuffer();
+        overlayBuffer = compositor.CreateBuffer();
+
+        isFramebufferInitialized = true;
+    }
+
+    // Disable 2D Textures
+    glDisable( GL_TEXTURE_2D );
+
+    // Enable the depth buffer
+    glEnable( GL_DEPTH_TEST );
+    glDepthFunc( GL_LESS );
+
+    // Setup blending, required for transparent objects
+    glEnable( GL_BLEND );
+    glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
+
+    glMatrixMode( GL_MODELVIEW );
+
+    // Set up the world <-> screen transformation
+    ComputeWorldScreenMatrix();
+    GLdouble matrixData[16] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };
+    matrixData[0]   = worldScreenMatrix.m_data[0][0];
+    matrixData[1]   = worldScreenMatrix.m_data[1][0];
+    matrixData[2]   = worldScreenMatrix.m_data[2][0];
+    matrixData[4]   = worldScreenMatrix.m_data[0][1];
+    matrixData[5]   = worldScreenMatrix.m_data[1][1];
+    matrixData[6]   = worldScreenMatrix.m_data[2][1];
+    matrixData[12]  = worldScreenMatrix.m_data[0][2];
+    matrixData[13]  = worldScreenMatrix.m_data[1][2];
+    matrixData[14]  = worldScreenMatrix.m_data[2][2];
+    glLoadMatrixd( matrixData );
+
+    // Set defaults
+    SetFillColor( fillColor );
+    SetStrokeColor( strokeColor );
+
+    // Unbind buffers - set compositor for direct drawing
+    compositor.SetBuffer( OPENGL_COMPOSITOR::DIRECT_RENDERING );
+
+    // Remove all previously stored items
+    nonCachedManager.Clear();
+    overlayManager.Clear();
+
+    cachedManager.BeginDrawing();
+    nonCachedManager.BeginDrawing();
+    overlayManager.BeginDrawing();
+}
+
+
+void OPENGL_GAL::EndDrawing()
+{
+    // Cached & non-cached containers are rendered to the same buffer
+    compositor.SetBuffer( mainBuffer );
+    nonCachedManager.EndDrawing();
+    cachedManager.EndDrawing();
+
+    // Overlay container is rendered to a different buffer
+    compositor.SetBuffer( overlayBuffer );
+    overlayManager.EndDrawing();
+
+    // Be sure that the framebuffer is not colorized (happens on specific GPU&drivers combinations)
+    glColor4d( 1.0, 1.0, 1.0, 1.0 );
+
+    // Draw the remaining contents, blit the rendering targets to the screen, swap the buffers
+    compositor.DrawBuffer( mainBuffer );
+    compositor.DrawBuffer( overlayBuffer );
+    blitCursor();
+
+    glFlush();
+    SwapBuffers();
+
+    delete clientDC;
+}
+
+
+void OPENGL_GAL::DrawLine( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint )
+{
+    const VECTOR2D  startEndVector = aEndPoint - aStartPoint;
+    double          lineAngle = startEndVector.Angle();
+
+    currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+    drawLineQuad( aStartPoint, aEndPoint );
+
+    // Line caps
+    if( lineWidth > 1.0 )
+    {
+        drawFilledSemiCircle( aStartPoint, lineWidth / 2, lineAngle + M_PI / 2 );
+        drawFilledSemiCircle( aEndPoint,   lineWidth / 2, lineAngle - M_PI / 2 );
+    }
+}
+
+
+void OPENGL_GAL::DrawSegment( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint,
+                              double aWidth )
+{
+    VECTOR2D startEndVector = aEndPoint - aStartPoint;
+    double   lineAngle      = startEndVector.Angle();
+
+    if( isFillEnabled )
+    {
+        // Filled tracks
+        currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+
+        SetLineWidth( aWidth );
+        drawLineQuad( aStartPoint, aEndPoint );
+
+        // Draw line caps
+        drawFilledSemiCircle( aStartPoint, aWidth / 2, lineAngle + M_PI / 2 );
+        drawFilledSemiCircle( aEndPoint,   aWidth / 2, lineAngle - M_PI / 2 );
+    }
+    else
+    {
+        // Outlined tracks
+        double lineLength = startEndVector.EuclideanNorm();
+
+        currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+        Save();
+
+        currentManager->Translate( aStartPoint.x, aStartPoint.y, 0.0 );
+        currentManager->Rotate( lineAngle, 0.0f, 0.0f, 1.0f );
+
+        drawLineQuad( VECTOR2D( 0.0,         aWidth / 2.0 ),
+                      VECTOR2D( lineLength,  aWidth / 2.0 ) );
+
+        drawLineQuad( VECTOR2D( 0.0,        -aWidth / 2.0 ),
+                      VECTOR2D( lineLength, -aWidth / 2.0 ) );
+
+        // Draw line caps
+        drawStrokedSemiCircle( VECTOR2D( 0.0, 0.0 ), aWidth / 2, M_PI / 2 );
+        drawStrokedSemiCircle( VECTOR2D( lineLength, 0.0 ), aWidth / 2, -M_PI / 2 );
+
+        Restore();
+    }
+}
+
+
+void OPENGL_GAL::DrawCircle( const VECTOR2D& aCenterPoint, double aRadius )
+{
+    if( isFillEnabled )
+    {
+        currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+
+        /* Draw a triangle that contains the circle, then shade it leaving only the circle.
+         *  Parameters given to setShader are indices of the triangle's vertices
+         *  (if you want to understand more, check the vertex shader source [shader.vert]).
+         *  Shader uses this coordinates to determine if fragments are inside the circle or not.
+         *       v2
+         *       /\
+         *      //\\
+         *  v0 /_\/_\ v1
+         */
+        currentManager->Shader( SHADER_FILLED_CIRCLE, 1.0 );
+        currentManager->Vertex( aCenterPoint.x - aRadius * sqrt( 3.0f ),            // v0
+                                aCenterPoint.y - aRadius, layerDepth );
+
+        currentManager->Shader( SHADER_FILLED_CIRCLE, 2.0 );
+        currentManager->Vertex( aCenterPoint.x + aRadius * sqrt( 3.0f ),             // v1
+                                aCenterPoint.y - aRadius, layerDepth );
+
+        currentManager->Shader( SHADER_FILLED_CIRCLE, 3.0 );
+        currentManager->Vertex( aCenterPoint.x, aCenterPoint.y + aRadius * 2.0f,    // v2
+                                layerDepth );
+    }
+
+    if( isStrokeEnabled )
+    {
+        currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+        /* Draw a triangle that contains the circle, then shade it leaving only the circle.
+         *  Parameters given to setShader are indices of the triangle's vertices
+         *  (if you want to understand more, check the vertex shader source [shader.vert]).
+         *  and the line width. Shader uses this coordinates to determine if fragments are
+         *  inside the circle or not.
+         *       v2
+         *       /\
+         *      //\\
+         *  v0 /_\/_\ v1
+         */
+        double outerRadius = aRadius + ( lineWidth / 2 );
+        currentManager->Shader( SHADER_STROKED_CIRCLE, 1.0, aRadius, lineWidth );
+        currentManager->Vertex( aCenterPoint.x - outerRadius * sqrt( 3.0f ),            // v0
+                                aCenterPoint.y - outerRadius, layerDepth );
+
+        currentManager->Shader( SHADER_STROKED_CIRCLE, 2.0, aRadius, lineWidth );
+        currentManager->Vertex( aCenterPoint.x + outerRadius * sqrt( 3.0f ),            // v1
+                                aCenterPoint.y - outerRadius, layerDepth );
+
+        currentManager->Shader( SHADER_STROKED_CIRCLE, 3.0, aRadius, lineWidth );
+        currentManager->Vertex( aCenterPoint.x, aCenterPoint.y + outerRadius * 2.0f,    // v2
+                                layerDepth );
+    }
+}
+
+
+void OPENGL_GAL::DrawArc( const VECTOR2D& aCenterPoint, double aRadius, double aStartAngle,
+                          double aEndAngle )
+{
+    if( aRadius <= 0 )
+        return;
+
+    // Swap the angles, if start angle is greater than end angle
+    SWAP( aStartAngle, >, aEndAngle );
+
+    Save();
+    currentManager->Translate( aCenterPoint.x, aCenterPoint.y, 0.0 );
+
+    if( isStrokeEnabled )
+    {
+        const double alphaIncrement = 2.0 * M_PI / CIRCLE_POINTS;
+        currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+        VECTOR2D p( cos( aStartAngle ) * aRadius, sin( aStartAngle ) * aRadius );
+        double alpha;
+
+        for( alpha = aStartAngle + alphaIncrement; alpha <= aEndAngle; alpha += alphaIncrement )
+        {
+            VECTOR2D p_next( cos( alpha ) * aRadius, sin( alpha ) * aRadius );
+            DrawLine( p, p_next );
+
+            p = p_next;
+        }
+
+        // Draw the last missing part
+        if( alpha != aEndAngle )
+        {
+            VECTOR2D p_last( cos( aEndAngle ) * aRadius, sin( aEndAngle ) * aRadius );
+            DrawLine( p, p_last );
+        }
+    }
+
+    if( isFillEnabled )
+    {
+        const double alphaIncrement = 2 * M_PI / CIRCLE_POINTS;
+        double alpha;
+        currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+        currentManager->Shader( SHADER_NONE );
+
+        // Triangle fan
+        for( alpha = aStartAngle; ( alpha + alphaIncrement ) < aEndAngle; )
+        {
+            currentManager->Vertex( 0.0, 0.0, 0.0 );
+            currentManager->Vertex( cos( alpha ) * aRadius, sin( alpha ) * aRadius, 0.0 );
+            alpha += alphaIncrement;
+            currentManager->Vertex( cos( alpha ) * aRadius, sin( alpha ) * aRadius, 0.0 );
+        }
+
+        // The last missing triangle
+        const VECTOR2D endPoint( cos( aEndAngle ) * aRadius, sin( aEndAngle ) * aRadius );
+        currentManager->Vertex( 0.0, 0.0, 0.0 );
+        currentManager->Vertex( cos( alpha ) * aRadius, sin( alpha ) * aRadius, 0.0 );
+        currentManager->Vertex( endPoint.x,    endPoint.y,     0.0 );
+    }
+
+    Restore();
+}
+
+
+void OPENGL_GAL::DrawRectangle( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint )
+{
+    // Compute the diagonal points of the rectangle
+    VECTOR2D diagonalPointA( aEndPoint.x, aStartPoint.y );
+    VECTOR2D diagonalPointB( aStartPoint.x, aEndPoint.y );
+
+    // Stroke the outline
+    if( isStrokeEnabled )
+    {
+        currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+        std::deque<VECTOR2D> pointList;
+        pointList.push_back( aStartPoint );
+        pointList.push_back( diagonalPointA );
+        pointList.push_back( aEndPoint );
+        pointList.push_back( diagonalPointB );
+        pointList.push_back( aStartPoint );
+        DrawPolyline( pointList );
+    }
+
+    // Fill the rectangle
+    if( isFillEnabled )
+    {
+        currentManager->Shader( SHADER_NONE );
+        currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+
+        currentManager->Vertex( aStartPoint.x, aStartPoint.y, layerDepth );
+        currentManager->Vertex( diagonalPointA.x, diagonalPointA.y, layerDepth );
+        currentManager->Vertex( aEndPoint.x, aEndPoint.y, layerDepth );
+
+        currentManager->Vertex( aStartPoint.x, aStartPoint.y, layerDepth );
+        currentManager->Vertex( aEndPoint.x, aEndPoint.y, layerDepth );
+        currentManager->Vertex( diagonalPointB.x, diagonalPointB.y, layerDepth );
+    }
+}
+
+
+void OPENGL_GAL::DrawPolyline( const std::deque<VECTOR2D>& aPointList )
+{
+    if( aPointList.size() < 2 )
+        return;
+
+    currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+    std::deque<VECTOR2D>::const_iterator it = aPointList.begin();
+
+    // Start from the second point
+    for( ++it; it != aPointList.end(); ++it )
+    {
+        const VECTOR2D startEndVector = ( *it - *( it - 1 ) );
+        double lineAngle = startEndVector.Angle();
+
+        drawLineQuad( *( it - 1 ), *it );
+
+        // There is no need to draw line caps on both ends of polyline's segments
+        drawFilledSemiCircle( *( it - 1 ), lineWidth / 2, lineAngle + M_PI / 2 );
+    }
+
+    // ..and now - draw the ending cap
+    const VECTOR2D startEndVector = ( *( it - 1 ) - *( it - 2 ) );
+    double lineAngle = startEndVector.Angle();
+    drawFilledSemiCircle( *( it - 1 ), lineWidth / 2, lineAngle - M_PI / 2 );
+}
+
+
+void OPENGL_GAL::DrawPolyline( const VECTOR2D aPointList[], int aListSize )
+{
+    if( aListSize < 2 )
+        return;
+
+    currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+
+    // Start from the second point
+    for( int i = 1; i < aListSize; ++i )
+    {
+        const VECTOR2D startEndVector = ( aPointList[i] - aPointList[i - 1] );
+        double lineAngle = startEndVector.Angle();
+
+        drawLineQuad( aPointList[i - 1], aPointList[i] );
+
+        // There is no need to draw line caps on both ends of polyline's segments
+        drawFilledSemiCircle( aPointList[i - 1], lineWidth / 2, lineAngle + M_PI / 2 );
+    }
+
+    // ..and now - draw the ending cap
+    const VECTOR2D startEndVector = ( aPointList[aListSize - 1] - aPointList[aListSize - 2] );
+    double lineAngle = startEndVector.Angle();
+    drawFilledSemiCircle( aPointList[aListSize - 1], lineWidth / 2, lineAngle - M_PI / 2 );
+}
+
+
+void OPENGL_GAL::DrawPolygon( const std::deque<VECTOR2D>& aPointList )
+{
+    currentManager->Shader( SHADER_NONE );
+    currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+
+    // Any non convex polygon needs to be tesselated
+    // for this purpose the GLU standard functions are used
+    TessParams params = { currentManager, tessIntersects };
+    gluTessBeginPolygon( tesselator, &params );
+    gluTessBeginContour( tesselator );
+
+    boost::shared_array<GLdouble> points( new GLdouble[3 * aPointList.size()] );
+    int v = 0;
+
+    for( std::deque<VECTOR2D>::const_iterator it = aPointList.begin(); it != aPointList.end(); ++it )
+    {
+        points[v]     = it->x;
+        points[v + 1] = it->y;
+        points[v + 2] = layerDepth;
+        gluTessVertex( tesselator, &points[v], &points[v] );
+        v += 3;
+    }
+
+    gluTessEndContour( tesselator );
+    gluTessEndPolygon( tesselator );
+
+    // Free allocated intersecting points
+    tessIntersects.clear();
+
+    // vertexList destroyed here
+}
+
+
+void OPENGL_GAL::DrawPolygon( const VECTOR2D aPointList[], int aListSize )
+{
+    currentManager->Shader( SHADER_NONE );
+    currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+
+    // Any non convex polygon needs to be tesselated
+    // for this purpose the GLU standard functions are used
+    TessParams params = { currentManager, tessIntersects };
+    gluTessBeginPolygon( tesselator, &params );
+    gluTessBeginContour( tesselator );
+
+    boost::shared_array<GLdouble> points( new GLdouble[3 * aListSize] );
+    int v = 0;
+    const VECTOR2D* ptr = aPointList;
+
+    for( int i = 0; i < aListSize; ++i )
+    {
+        points[v]     = ptr->x;
+        points[v + 1] = ptr->y;
+        points[v + 2] = layerDepth;
+        gluTessVertex( tesselator, &points[v], &points[v] );
+        ++ptr;
+        v += 3;
+    }
+
+    gluTessEndContour( tesselator );
+    gluTessEndPolygon( tesselator );
+
+    // Free allocated intersecting points
+    tessIntersects.clear();
+
+    // vertexList destroyed here
+}
+
+
+void OPENGL_GAL::DrawCurve( const VECTOR2D& aStartPoint, const VECTOR2D& aControlPointA,
+                            const VECTOR2D& aControlPointB, const VECTOR2D& aEndPoint )
+{
+    // FIXME The drawing quality needs to be improved
+    // FIXME Perhaps choose a quad/triangle strip instead?
+    // FIXME Brute force method, use a better (recursive?) algorithm
+
+    std::deque<VECTOR2D> pointList;
+
+    double t  = 0.0;
+    double dt = 1.0 / (double) CURVE_POINTS;
+
+    for( int i = 0; i <= CURVE_POINTS; i++ )
+    {
+        double omt  = 1.0 - t;
+        double omt2 = omt * omt;
+        double omt3 = omt * omt2;
+        double t2   = t * t;
+        double t3   = t * t2;
+
+        VECTOR2D vertex = omt3 * aStartPoint + 3.0 * t * omt2 * aControlPointA
+                          + 3.0 * t2 * omt * aControlPointB + t3 * aEndPoint;
+
+        pointList.push_back( vertex );
+
+        t += dt;
+    }
+
+    DrawPolyline( pointList );
+}
+
+
+void OPENGL_GAL::ResizeScreen( int aWidth, int aHeight )
+{
+    screenSize = VECTOR2I( aWidth, aHeight );
+
+#ifdef RETINA_OPENGL_PATCH
+    const float scaleFactor = GetBackingScaleFactor();
+#else
+    const float scaleFactor = 1.0f;
+#endif
+
+    // Resize framebuffers
+    compositor.Resize( aWidth * scaleFactor, aHeight * scaleFactor );
+    isFramebufferInitialized = false;
+
+    wxGLCanvas::SetSize( aWidth, aHeight );
+}
+
+
+bool OPENGL_GAL::Show( bool aShow )
+{
+    bool s = wxGLCanvas::Show( aShow );
+
+    if( aShow )
+        wxGLCanvas::Raise();
+
+    return s;
+}
+
+
+void OPENGL_GAL::Flush()
+{
+    glFlush();
+}
+
+
+void OPENGL_GAL::ClearScreen( const COLOR4D& aColor )
+{
+    // Clear screen
+    glClearColor( aColor.r, aColor.g, aColor.b, aColor.a );
+    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
+}
+
+
+void OPENGL_GAL::Transform( const MATRIX3x3D& aTransformation )
+{
+    GLdouble matrixData[16] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };
+
+    matrixData[0]   = aTransformation.m_data[0][0];
+    matrixData[1]   = aTransformation.m_data[1][0];
+    matrixData[2]   = aTransformation.m_data[2][0];
+    matrixData[4]   = aTransformation.m_data[0][1];
+    matrixData[5]   = aTransformation.m_data[1][1];
+    matrixData[6]   = aTransformation.m_data[2][1];
+    matrixData[12]  = aTransformation.m_data[0][2];
+    matrixData[13]  = aTransformation.m_data[1][2];
+    matrixData[14]  = aTransformation.m_data[2][2];
+
+    glMultMatrixd( matrixData );
+}
+
+
+void OPENGL_GAL::Rotate( double aAngle )
+{
+    currentManager->Rotate( aAngle, 0.0f, 0.0f, 1.0f );
+}
+
+
+void OPENGL_GAL::Translate( const VECTOR2D& aVector )
+{
+    currentManager->Translate( aVector.x, aVector.y, 0.0f );
+}
+
+
+void OPENGL_GAL::Scale( const VECTOR2D& aScale )
+{
+    currentManager->Scale( aScale.x, aScale.y, 0.0f );
+}
+
+
+void OPENGL_GAL::Save()
+{
+    currentManager->PushMatrix();
+}
+
+
+void OPENGL_GAL::Restore()
+{
+    currentManager->PopMatrix();
+}
+
+
+int OPENGL_GAL::BeginGroup()
+{
+    isGrouping = true;
+
+    boost::shared_ptr<VERTEX_ITEM> newItem( new VERTEX_ITEM( cachedManager ) );
+    int groupNumber = getNewGroupNumber();
+    groups.insert( std::make_pair( groupNumber, newItem ) );
+
+    return groupNumber;
+}
+
+
+void OPENGL_GAL::EndGroup()
+{
+    cachedManager.FinishItem();
+    isGrouping = false;
+}
+
+
+void OPENGL_GAL::DrawGroup( int aGroupNumber )
+{
+    cachedManager.DrawItem( *groups[aGroupNumber] );
+}
+
+
+void OPENGL_GAL::ChangeGroupColor( int aGroupNumber, const COLOR4D& aNewColor )
+{
+    cachedManager.ChangeItemColor( *groups[aGroupNumber], aNewColor );
+}
+
+
+void OPENGL_GAL::ChangeGroupDepth( int aGroupNumber, int aDepth )
+{
+    cachedManager.ChangeItemDepth( *groups[aGroupNumber], aDepth );
+}
+
+
+void OPENGL_GAL::DeleteGroup( int aGroupNumber )
+{
+    // Frees memory in the container as well
+    groups.erase( aGroupNumber );
+}
+
+
+void OPENGL_GAL::ClearCache()
+{
+    groups.clear();
+    cachedManager.Clear();
+}
+
+
+void OPENGL_GAL::SaveScreen()
+{
+    wxASSERT_MSG( false, wxT( "Not implemented yet" ) );
+}
+
+
+void OPENGL_GAL::RestoreScreen()
+{
+    wxASSERT_MSG( false, wxT( "Not implemented yet" ) );
+}
+
+
+void OPENGL_GAL::SetTarget( RENDER_TARGET aTarget )
+{
+    switch( aTarget )
+    {
+    default:
+    case TARGET_CACHED:
+        currentManager = &cachedManager;
+        break;
+
+    case TARGET_NONCACHED:
+        currentManager = &nonCachedManager;
+        break;
+
+    case TARGET_OVERLAY:
+        currentManager = &overlayManager;
+        break;
+    }
+
+    currentTarget = aTarget;
+}
+
+
+RENDER_TARGET OPENGL_GAL::GetTarget() const
+{
+    return currentTarget;
+}
+
+
+void OPENGL_GAL::ClearTarget( RENDER_TARGET aTarget )
+{
+    // Save the current state
+    unsigned int oldTarget = compositor.GetBuffer();
+
+    switch( aTarget )
+    {
+    // Cached and noncached items are rendered to the same buffer
+    default:
+    case TARGET_CACHED:
+    case TARGET_NONCACHED:
+        compositor.SetBuffer( mainBuffer );
+        break;
+
+    case TARGET_OVERLAY:
+        compositor.SetBuffer( overlayBuffer );
+        break;
+    }
+
+    compositor.ClearBuffer();
+
+    // Restore the previous state
+    compositor.SetBuffer( oldTarget );
+}
+
+
+void OPENGL_GAL::DrawCursor( const VECTOR2D& aCursorPosition )
+{
+    // Now we should only store the position of the mouse cursor
+    // The real drawing routines are in blitCursor()
+    VECTOR2D screenCursor = worldScreenMatrix * aCursorPosition;
+
+    cursorPosition = screenWorldMatrix * VECTOR2D( screenCursor.x, screenSize.y - screenCursor.y );
+}
+
+
+void OPENGL_GAL::drawGridLine( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint )
+{
+    compositor.SetBuffer( mainBuffer );
+
+    // We do not need a very precise comparison here (the lineWidth is set by GAL::DrawGrid())
+    if( fabs( lineWidth - 2.0 * gridLineWidth / worldScale ) < 0.1 )
+        glLineWidth( 1.0 );
+    else
+        glLineWidth( 2.0 );
+
+    glColor4d( gridColor.r, gridColor.g, gridColor.b, gridColor.a );
+
+    glBegin( GL_LINES );
+    glVertex3d( aStartPoint.x, aStartPoint.y, layerDepth );
+    glVertex3d( aEndPoint.x, aEndPoint.y, layerDepth );
+    glEnd();
+
+    // Restore the default color, so textures will be drawn properly
+    glColor4d( 1.0, 1.0, 1.0, 1.0 );
+}
+
+
+void OPENGL_GAL::drawLineQuad( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint )
+{
+    /* Helper drawing:                   ____--- v3       ^
+     *                           ____---- ...   \          \
+     *                   ____----      ...       \   end    \
+     *     v1    ____----           ...    ____----          \ width
+     *       ----                ...___----        \          \
+     *       \             ___...--                 \          v
+     *        \    ____----...                ____---- v2
+     *         ----     ...           ____----
+     *  start   \    ...      ____----
+     *           \... ____----
+     *            ----
+     *            v0
+     * dots mark triangles' hypotenuses
+     */
+
+    VECTOR2D startEndVector = aEndPoint - aStartPoint;
+    double   lineLength     = startEndVector.EuclideanNorm();
+
+    if( lineLength <= 0.0 )
+        return;
+
+    double   scale          = 0.5 * lineWidth / lineLength;
+
+    // The perpendicular vector also needs transformations
+    glm::vec4 vector = currentManager->GetTransformation() *
+                       glm::vec4( -startEndVector.y * scale, startEndVector.x * scale, 0.0, 0.0 );
+
+    // Line width is maintained by the vertex shader
+    currentManager->Shader( SHADER_LINE, vector.x, vector.y, lineWidth );
+    currentManager->Vertex( aStartPoint.x, aStartPoint.y, layerDepth );    // v0
+
+    currentManager->Shader( SHADER_LINE, -vector.x, -vector.y, lineWidth );
+    currentManager->Vertex( aStartPoint.x, aStartPoint.y, layerDepth );    // v1
+
+    currentManager->Shader( SHADER_LINE, -vector.x, -vector.y, lineWidth );
+    currentManager->Vertex( aEndPoint.x, aEndPoint.y, layerDepth );        // v3
+
+    currentManager->Shader( SHADER_LINE, vector.x, vector.y, lineWidth );
+    currentManager->Vertex( aStartPoint.x, aStartPoint.y, layerDepth );    // v0
+
+    currentManager->Shader( SHADER_LINE, -vector.x, -vector.y, lineWidth );
+    currentManager->Vertex( aEndPoint.x, aEndPoint.y, layerDepth );        // v3
+
+    currentManager->Shader( SHADER_LINE, vector.x, vector.y, lineWidth );
+    currentManager->Vertex( aEndPoint.x, aEndPoint.y, layerDepth );        // v2
+}
+
+
+void OPENGL_GAL::drawSemiCircle( const VECTOR2D& aCenterPoint, double aRadius, double aAngle )
+{
+    if( isFillEnabled )
+    {
+        currentManager->Color( fillColor.r, fillColor.g, fillColor.b, fillColor.a );
+        drawFilledSemiCircle( aCenterPoint, aRadius, aAngle );
+    }
+
+    if( isStrokeEnabled )
+    {
+        currentManager->Color( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );
+        drawStrokedSemiCircle( aCenterPoint, aRadius, aAngle );
+    }
+}
+
+
+void OPENGL_GAL::drawFilledSemiCircle( const VECTOR2D& aCenterPoint, double aRadius,
+                                       double aAngle )
+{
+    Save();
+    currentManager->Translate( aCenterPoint.x, aCenterPoint.y, 0.0f );
+    currentManager->Rotate( aAngle, 0.0f, 0.0f, 1.0f );
+
+    /* Draw a triangle that contains the semicircle, then shade it to leave only
+     * the semicircle. Parameters given to setShader are indices of the triangle's vertices
+     * (if you want to understand more, check the vertex shader source [shader.vert]).
+     * Shader uses these coordinates to determine if fragments are inside the semicircle or not.
+     *       v2
+     *       /\
+     *      /__\
+     *  v0 //__\\ v1
+     */
+    currentManager->Shader( SHADER_FILLED_CIRCLE, 4.0f );
+    currentManager->Vertex( -aRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth );     // v0
+
+    currentManager->Shader( SHADER_FILLED_CIRCLE, 5.0f );
+    currentManager->Vertex( aRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth );      // v1
+
+    currentManager->Shader( SHADER_FILLED_CIRCLE, 6.0f );
+    currentManager->Vertex( 0.0f, aRadius * 2.0f, layerDepth );                     // v2
+
+    Restore();
+}
+
+
+void OPENGL_GAL::drawStrokedSemiCircle( const VECTOR2D& aCenterPoint, double aRadius,
+                                        double aAngle )
+{
+    double outerRadius = aRadius + ( lineWidth / 2 );
+
+    Save();
+    currentManager->Translate( aCenterPoint.x, aCenterPoint.y, 0.0f );
+    currentManager->Rotate( aAngle, 0.0f, 0.0f, 1.0f );
+
+    /* Draw a triangle that contains the semicircle, then shade it to leave only
+     * the semicircle. Parameters given to setShader are indices of the triangle's vertices
+     * (if you want to understand more, check the vertex shader source [shader.vert]), the
+     * radius and the line width. Shader uses these coordinates to determine if fragments are
+     * inside the semicircle or not.
+     *       v2
+     *       /\
+     *      /__\
+     *  v0 //__\\ v1
+     */
+    currentManager->Shader( SHADER_STROKED_CIRCLE, 4.0f, aRadius, lineWidth );
+    currentManager->Vertex( -outerRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth );     // v0
+
+    currentManager->Shader( SHADER_STROKED_CIRCLE, 5.0f, aRadius, lineWidth );
+    currentManager->Vertex( outerRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth );      // v1
+
+    currentManager->Shader( SHADER_STROKED_CIRCLE, 6.0f, aRadius, lineWidth );
+    currentManager->Vertex( 0.0f, outerRadius * 2.0f, layerDepth );                     // v2
+
+    Restore();
+}
+
+
+void OPENGL_GAL::onPaint( wxPaintEvent& WXUNUSED( aEvent ) )
+{
+    PostPaint();
+}
+
+
+void OPENGL_GAL::skipMouseEvent( wxMouseEvent& aEvent )
+{
+    // Post the mouse event to the event listener registered in constructor, if any
+    if( mouseListener )
+        wxPostEvent( mouseListener, aEvent );
+}
+
+
+void OPENGL_GAL::blitCursor()
+{
+    if( !isCursorEnabled )
+        return;
+
+    compositor.SetBuffer( OPENGL_COMPOSITOR::DIRECT_RENDERING );
+
+    VECTOR2D cursorBegin  = cursorPosition - cursorSize / ( 2 * worldScale );
+    VECTOR2D cursorEnd    = cursorPosition + cursorSize / ( 2 * worldScale );
+    VECTOR2D cursorCenter = ( cursorBegin + cursorEnd ) / 2;
+
+    glDisable( GL_TEXTURE_2D );
+    glLineWidth( 1.0 );
+    glColor4d( cursorColor.r, cursorColor.g, cursorColor.b, cursorColor.a );
+
+    glBegin( GL_LINES );
+    glVertex2d( cursorCenter.x, cursorBegin.y );
+    glVertex2d( cursorCenter.x, cursorEnd.y );
+
+    glVertex2d( cursorBegin.x, cursorCenter.y );
+    glVertex2d( cursorEnd.x, cursorCenter.y );
+    glEnd();
+}
+
+
+unsigned int OPENGL_GAL::getNewGroupNumber()
+{
+    wxASSERT_MSG( groups.size() < std::numeric_limits<unsigned int>::max(),
+                  wxT( "There are no free slots to store a group" ) );
+
+    while( groups.find( groupCounter ) != groups.end() )
+    {
+        groupCounter++;
+    }
+
+    return groupCounter++;
+}
+
+
+bool OPENGL_GAL::runTest()
+{
+    wxDialog dlgtest( GetParent(), -1, wxT( "opengl test" ), wxPoint( 50, 50 ),
+                      wxDLG_UNIT( GetParent(), wxSize( 50, 50 ) ) );
+    OPENGL_TEST* test = new OPENGL_TEST( &dlgtest, this );
+
+    dlgtest.Raise();         // on Linux, on some windows managers (Unity for instance) this is needed to actually show the dialog
+    dlgtest.ShowModal();
+    bool result = test->IsOk();
+
+    if( !result )
+        throw std::runtime_error( test->GetError() );
+
+    return result;
+}
+
+
+OPENGL_GAL::OPENGL_TEST::OPENGL_TEST( wxDialog* aParent, OPENGL_GAL* aGal ) :
+    wxGLCanvas( aParent, wxID_ANY, glAttributes, wxDefaultPosition,
+                wxDefaultSize, 0, wxT( "GLCanvas" ) ),
+    m_parent( aParent ), m_gal( aGal ), m_tested( false ), m_result( false )
+{
+    m_timeoutTimer.SetOwner( this );
+    Connect( wxEVT_PAINT, wxPaintEventHandler( OPENGL_GAL::OPENGL_TEST::Render ) );
+    Connect( wxEVT_TIMER, wxTimerEventHandler( OPENGL_GAL::OPENGL_TEST::OnTimeout ) );
+    m_parent->Connect( wxEVT_PAINT, wxPaintEventHandler( OPENGL_GAL::OPENGL_TEST::OnDialogPaint ), NULL, this );
+}
+
+
+void OPENGL_GAL::OPENGL_TEST::Render( wxPaintEvent& WXUNUSED( aEvent ) )
+{
+    if( !m_tested )
+    {
+        if( !IsShownOnScreen() )
+            return;
+
+        m_timeoutTimer.Stop();
+        m_result = true;    // Assume everything is fine, until proven otherwise
+
+        // One test is enough - close the testing dialog when the test is finished
+        Disconnect( wxEVT_PAINT, wxPaintEventHandler( OPENGL_GAL::OPENGL_TEST::Render ) );
+        CallAfter( boost::bind( &wxDialog::EndModal, m_parent, wxID_NONE ) );
+
+        SetCurrent( *OPENGL_GAL::glContext );
+        GLenum err = glewInit();
+
+        if( GLEW_OK != err )
+        {
+            error( (const char*) glewGetErrorString( err ) );
+            return;
+        }
+        else
+        {
+            wxLogDebug( wxString( wxT( "Status: Using GLEW " ) ) +
+                        FROM_UTF8( (char*) glewGetString( GLEW_VERSION ) ) );
+        }
+
+        // Check the OpenGL version (minimum 2.1 is required)
+        if( GLEW_VERSION_2_1 )
+        {
+            wxLogInfo( wxT( "OpenGL 2.1 supported." ) );
+        }
+        else
+        {
+            error( "OpenGL 2.1 or higher is required!" );
+            return;
+        }
+
+        // Framebuffers have to be supported
+        if( !GLEW_EXT_framebuffer_object )
+        {
+            error( "Framebuffer objects are not supported!" );
+            return;
+        }
+
+        // Vertex buffer has to be supported
+        if( !GLEW_ARB_vertex_buffer_object )
+        {
+            error( "Vertex buffer objects are not supported!" );
+            return;
+        }
+
+        // Prepare shaders
+        if( !m_gal->shader.LoadBuiltinShader( 0, SHADER_TYPE_VERTEX ) )
+        {
+            error( "Cannot compile vertex shader!" );
+            return;
+        }
+
+        if( !m_gal->shader.LoadBuiltinShader( 1, SHADER_TYPE_FRAGMENT ) )
+        {
+            error( "Cannot compile fragment shader!" );
+            return;
+        }
+
+        if( !m_gal->shader.Link() )
+        {
+            error( "Cannot link the shaders!" );
+            return;
+        }
+
+        m_tested = true;
+    }
+}
+
+
+void OPENGL_GAL::OPENGL_TEST::OnTimeout( wxTimerEvent& aEvent )
+{
+    error( "Could not create OpenGL canvas" );
+    m_parent->EndModal( wxID_NONE );
+}
+
+
+void OPENGL_GAL::OPENGL_TEST::OnDialogPaint( wxPaintEvent& aEvent )
+{
+    // GL canvas may never appear on the screen (e.g. due to missing GL extensions), and the test
+    // will not be run. Therefore give at most a second to perform the test, otherwise we conclude
+    // it has failed.
+    // Also, wxWidgets OnShow event is triggered before a window is shown, therefore here we use
+    // OnPaint event, which is executed when a window is actually visible.
+    m_timeoutTimer.StartOnce( 1000 );
+}
+
+
+void OPENGL_GAL::OPENGL_TEST::error( const std::string& aError )
+{
+    m_timeoutTimer.Stop();
+    m_result = false;
+    m_tested = true;
+    m_error = aError;
+}
+
+// ------------------------------------- // Callback functions for the tesselator // ------------------------------------- // Compare Redbook Chapter 11
+void CALLBACK VertexCallback( GLvoid* aVertexPtr, void* aData )
+{
+    GLdouble* vertex = static_cast<GLdouble*>( aVertexPtr );
+    OPENGL_GAL::TessParams* param = static_cast<OPENGL_GAL::TessParams*>( aData );
+    VERTEX_MANAGER* vboManager = param->vboManager;
+
+    if( vboManager )
+        vboManager->Vertex( vertex[0], vertex[1], vertex[2] );
+}
+
+
+void CALLBACK CombineCallback( GLdouble coords[3],
+                               GLdouble* vertex_data[4],
+                               GLfloat weight[4], GLdouble** dataOut, void* aData )
+{
+    GLdouble* vertex = new GLdouble[3];
+    OPENGL_GAL::TessParams* param = static_cast<OPENGL_GAL::TessParams*>( aData );
+
+    // Save the pointer so we can delete it later
+    param->intersectPoints.push_back( boost::shared_array<GLdouble>( vertex ) );
+
+    memcpy( vertex, coords, 3 * sizeof(GLdouble) );
+
+    *dataOut = vertex;
+}
+
+
+void CALLBACK EdgeCallback( GLboolean aEdgeFlag )
+{
+    // This callback is needed to force GLU tesselator to use triangles only
+}
+
+
+void CALLBACK ErrorCallback( GLenum aErrorCode )
+{
+    //throw std::runtime_error( std::string( "Tessellation error: " ) +
+                              //std::string( (const char*) gluErrorString( aErrorCode ) );
+}
+
+
+static void InitTesselatorCallbacks( GLUtesselator* aTesselator )
+{
+    gluTessCallback( aTesselator, GLU_TESS_VERTEX_DATA,  ( void (CALLBACK*)() )VertexCallback );
+    gluTessCallback( aTesselator, GLU_TESS_COMBINE_DATA, ( void (CALLBACK*)() )CombineCallback );
+    gluTessCallback( aTesselator, GLU_TESS_EDGE_FLAG,    ( void (CALLBACK*)() )EdgeCallback );
+    gluTessCallback( aTesselator, GLU_TESS_ERROR,        ( void (CALLBACK*)() )ErrorCallback );
+}