opengl/pyramid/pyramid.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:        pyramid.cpp
// Purpose:     OpenGL version >= 3.2 sample
// Author:      Manuel Martin
// Created:     2015/11/16
// Copyright:   (c) 2015 Manuel Martin
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ============================================================================
// declarations
// ============================================================================

// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------

// For compilers that support precompilation, includes "wx/wx.h".
#include "wx/wxprec.h"


#ifndef WX_PRECOMP
    #include "wx/wx.h"
#endif

#if !wxUSE_GLCANVAS
    #error "OpenGL required: set wxUSE_GLCANVAS to 1 and rebuild the library"
#endif

// Due to oglpfuncs.h needs to be included before gl.h (to avoid some declarations),
// we include glcanvas.h after oglstuff.h
#include "oglstuff.h"
#include "wx/glcanvas.h"
#include "pyramid.h"

// the application icon (under Windows and OS/2 it is in resources and even
// though we could still include the XPM here it would be unused)
#ifndef wxHAS_IMAGES_IN_RESOURCES
    #include "../../sample.xpm"
#endif

wxBEGIN_EVENT_TABLE(MyFrame, wxFrame)
    EVT_MENU(Pyramid_Quit,  MyFrame::OnQuit)
    EVT_MENU(Pyramid_About, MyFrame::OnAbout)
#if wxUSE_LOGWINDOW
    EVT_MENU(Pyramid_LogW,  MyFrame::OnLogWindow)
#endif // wxUSE_LOGWINDOW
wxEND_EVENT_TABLE()

wxIMPLEMENT_APP(MyApp);

// ============================================================================
// implementation
// ============================================================================

// ----------------------------------------------------------------------------
// the application class
// ----------------------------------------------------------------------------

// 'Main program' equivalent: the program execution "starts" here
bool MyApp::OnInit()
{
    if ( !wxApp::OnInit() )
        return false;

    // create the main application window
    MyFrame* frame = new MyFrame("wxWidgets OpenGL Pyramid Sample");

    //Exit if the required visual attributes or OGL context couldn't be created
    if ( ! frame->OGLAvailable() )
        return false;

    // As of October 2015 GTK+ needs the frame to be shown before we call SetCurrent()
    frame->Show(true);

    return true;
}

// ----------------------------------------------------------------------------
// main frame
// ----------------------------------------------------------------------------

// frame constructor
MyFrame::MyFrame(const wxString& title)
       : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(500, 400))
{
    // set the frame icon
    SetIcon(wxICON(sample));

#if wxUSE_MENUS
    // create a menu bar
    wxMenu *fileMenu = new wxMenu;

    // the "About" item should be in the help menu
    wxMenu *helpMenu = new wxMenu;
    helpMenu->Append(Pyramid_About, "&About\tF1", "Show about dialog");

#if wxUSE_LOGWINDOW
    fileMenu->Append(Pyramid_LogW, "&Log window", "Open the log window");
    fileMenu->AppendSeparator();
#endif // wxUSE_LOGWINDOW
    fileMenu->Append(Pyramid_Quit, "E&xit\tAlt-X", "Quit this program");

    // now append the freshly created menu to the menu bar...
    wxMenuBar *menuBar = new wxMenuBar();
    menuBar->Append(fileMenu, "&File");
    menuBar->Append(helpMenu, "&Help");

    // ... and attach this menu bar to the frame
    SetMenuBar(menuBar);
#endif // wxUSE_MENUS

#if wxUSE_STATUSBAR
    // create a status bar just for fun (by default with 1 pane only)
    CreateStatusBar(2);
    SetStatusText("Welcome to wxWidgets!");
#endif // wxUSE_STATUSBAR

#if wxUSE_LOGWINDOW
    //Open a log window, don't show it though
    m_LogWin = new wxLogWindow(NULL, "Pyramid log window", false, false);
    wxLog::SetActiveTarget(m_LogWin);
#endif // wxUSE_LOGWINDOW

    // The canvas
    m_mycanvas = NULL;
    wxGLAttributes vAttrs;
    // Defaults should be accepted
    vAttrs.PlatformDefaults().Defaults().EndList();
    bool accepted = wxGLCanvas::IsDisplaySupported(vAttrs) ;

    if ( accepted )
    {
#if wxUSE_LOGWINDOW
        wxLogMessage("The display supports required visual attributes.");
#endif // wxUSE_LOGWINDOW
    }
    else
    {
#if wxUSE_LOGWINDOW
        wxLogMessage("First try with OpenGL default visual attributes failed.");
#endif // wxUSE_LOGWINDOW
        // Try again without sample buffers
        vAttrs.Reset();
        vAttrs.PlatformDefaults().RGBA().DoubleBuffer().Depth(16).EndList();
        accepted = wxGLCanvas::IsDisplaySupported(vAttrs) ;

        if ( !accepted )
        {
            wxMessageBox("Visual attributes for OpenGL are not accepted.\nThe app will exit now.",
                         "Error with OpenGL", wxOK | wxICON_ERROR);
        }
        else
        {
#if wxUSE_LOGWINDOW
            wxLogMessage("Second try with other visual attributes worked.");
#endif // wxUSE_LOGWINDOW
        }
    }

    if ( accepted )
        m_mycanvas = new MyGLCanvas(this, vAttrs);

    SetMinSize(wxSize(250, 200));
}


// event handlers

void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
{
    // true is to force the frame to close
    Close(true);
}

void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
{
    wxMessageBox(wxString::Format
                 (
                    "Welcome to %s!\n"
                    "\n"
                    "This is the wxWidgets OpenGL Pyramid sample.\n"
                    "%s\n",
                    wxVERSION_STRING,
                    m_OGLString
                 ),
                 "About wxWidgets pyramid sample",
                 wxOK | wxICON_INFORMATION,
                 this);
}

#if wxUSE_LOGWINDOW
void MyFrame::OnLogWindow(wxCommandEvent& WXUNUSED(event))
{
    if ( m_LogWin->GetFrame()->IsIconized() )
        m_LogWin->GetFrame()->Restore();

    if ( ! m_LogWin->GetFrame()->IsShown() )
        m_LogWin->Show();

    m_LogWin->GetFrame()->SetFocus();
}
#endif // wxUSE_LOGWINDOW

bool MyFrame::OGLAvailable()
{
    //Test if visual attributes were accepted.
    if ( ! m_mycanvas )
        return false;

    //Test if OGL context could be created.
    return m_mycanvas->OglCtxAvailable();
}

// ----------------------------------------------------------------------------
// Function for receiving messages from OGLstuff and passing them to the log window
// ----------------------------------------------------------------------------
void fOGLErrHandler(int err, int glerr, const GLchar* glMsg)
{
#if wxUSE_LOGWINDOW
    wxString msg;

    switch (err)
    {
    case myoglERR_SHADERCREATE:
        msg = _("Error in shader creation.");
        break;
    case myoglERR_SHADERCOMPILE:
        msg = _("Error in shader compilation.");
        break;
    case myoglERR_SHADERLINK:
        msg = _("Error in shader linkage.");
        break;
    case myoglERR_SHADERLOCATION:
        msg = _("Error: Can't get uniforms locations.");
        break;
    case myoglERR_BUFFER:
        msg = _("Error: Can't load buffer. Likely out of GPU memory.");
        break;
    case myoglERR_TEXTIMAGE:
        msg = _("Error: Can't load texture. Likely out of GPU memory.");
        break;
    case myoglERR_DRAWING_TRI:
        msg = _("Error: Can't draw the triangles.");
        break;
    case myoglERR_DRAWING_STR:
        msg = _("Error: Can't draw the string.");
        break;
    case myoglERR_JUSTLOG:
        msg = _("Log info: ");
        break;
    default:
        msg = _("Not a GL message.");
    }

    if ( glerr != GL_NO_ERROR )
        msg += wxString::Format(_(" GL error %d. "), glerr);
    else if ( err == 0 )
        msg = _("Information: ");
    else if ( err != myoglERR_JUSTLOG )
        msg += _(" GL reports: ");

    if ( glMsg != NULL )
        msg += wxString::FromUTF8( reinterpret_cast<const char *>(glMsg) );

    wxLogMessage(msg);
#endif // wxUSE_LOGWINDOW
}

// ----------------------------------------------------------------------------
// These two functions allow us to convert a wxString into a RGBA pixels array
// ----------------------------------------------------------------------------

// Creates a 4-bytes-per-pixel, RGBA array from a wxImage.
// If the image has alpha channel, it's used. If not, pixels with 'cTrans' color
// get 'cAlpha' alpha; an the rest of pixels get alpha=255 (opaque).
//
// NOTE: The returned pointer must be deleted somewhere in the app.
unsigned char* MyImgToArray(const wxImage& img, const wxColour& cTrans, unsigned char cAlpha)
{
    int w = img.GetWidth();
    int h = img.GetHeight();
    int siz = w * h;
    unsigned char *resArr = new unsigned char [siz * 4];
    unsigned char *res = resArr;
    unsigned char *sdata = img.GetData();
    unsigned char *alpha = NULL;
    if ( img.HasAlpha() )
        alpha = img.GetAlpha();
    // Pixel by pixel
    for ( int i = 0; i < siz; i++ )
    {   //copy the colour
        res[0] = sdata[0] ;
        res[1] = sdata[1] ;
        res[2] = sdata[2] ;
        if ( alpha != NULL )
        {   //copy alpha
            res[3] = alpha[i] ;
        }
        else
        {   // Colour cTrans gets cAlpha transparency
            if ( res[0] == cTrans.Red() && res[1] == cTrans.Green() && res[2] == cTrans.Blue() )
                res[3] = cAlpha;
            else
                res[3] = 255 ;
        }
        sdata += 3 ;
        res += 4 ;
    }

    return resArr;
}

// Creates an array of bytes that defines the pixels of the string.
// The background color has cAlpha transparency. 0=transparent, 255=opaque
//
// NOTE: The returned pointer must be deleted somewhere in the app.
unsigned char* MyTextToPixels(const wxString& sText,     // The string
                              const wxFont& sFont,       // Font to use
                              const wxColour& sForeColo, // Foreground colour
                              const wxColour& sBackColo, // Background colour
                              unsigned char cAlpha,      // Background transparency
                              int* width, int* height)   // Image sizes
{
    if ( sText.IsEmpty() )
        return NULL;

    // The dc where we temporally draw
    wxMemoryDC mdc;

    mdc.SetFont(sFont);

    // Measure
    mdc.GetMultiLineTextExtent(sText, width, height);

    /* This code should be used for old graphics cards.
       But this sample uses OGL Core Profile, so the card is not that old.

    // Adjust sizes to power of two. Needed for old cards.
    int sizP2 = 4;
    while ( sizP2 < *width )
        sizP2 *= 2;
    *width = sizP2;
    sizP2 = 4;
    while ( sizP2 < *height )
        sizP2 *= 2;
    *height = sizP2;
    */

    // Now we know dimensions, let's draw into a memory dc
    wxBitmap bmp(*width, *height, 24);
    mdc.SelectObject(bmp);
    // If we have multiline string, perhaps not all of the bmp is used
    wxBrush brush(sBackColo);
    mdc.SetBackground(brush);
    mdc.Clear(); // Make sure all of bmp is cleared
    // Colours
    mdc.SetBackgroundMode(wxPENSTYLE_SOLID);
    mdc.SetTextBackground(sBackColo);
    mdc.SetTextForeground(sForeColo);
    // We draw the string and get it as an image.
    // NOTE: OpenGL axis are bottom to up. Be aware when setting the texture coords.
    mdc.DrawText(sText, 0, 0);
    mdc.SelectObject(wxNullBitmap); // bmp must be detached from wxMemoryDC

    // Bytes from the image. Background pixels become transparent with the
    // cAlpha transparency value.
    unsigned char *res = MyImgToArray(bmp.ConvertToImage(), sBackColo, cAlpha);

    return res;
}


// ----------------------------------------------------------------------------
// The canvas inside the frame. Our OpenGL connection
// ----------------------------------------------------------------------------

wxBEGIN_EVENT_TABLE(MyGLCanvas, wxGLCanvas)
    EVT_PAINT(MyGLCanvas::OnPaint)
    EVT_SIZE(MyGLCanvas::OnSize)
    EVT_MOUSE_EVENTS(MyGLCanvas::OnMouse)
wxEND_EVENT_TABLE()

//We create a wxGLContext in this constructor.
//We do OGL initialization at OnSize().
MyGLCanvas::MyGLCanvas(MyFrame* parent, const wxGLAttributes& canvasAttrs)
                       : wxGLCanvas(parent, canvasAttrs)
{
    m_parent = parent;

    m_oglManager = NULL;
    m_winHeight = 0; // We have not been sized yet

    // Explicitly create a new rendering context instance for this canvas.
    wxGLContextAttrs ctxAttrs;
#ifndef __WXMAC__
    // An impossible context, just to test IsOk()
    ctxAttrs.PlatformDefaults().OGLVersion(99, 2).EndList();
    m_oglContext = new wxGLContext(this, NULL, &ctxAttrs);

    if ( !m_oglContext->IsOK() )
    {
#if wxUSE_LOGWINDOW
        wxLogMessage("Trying to set OpenGL 99.2 failed, as expected.");
#endif // wxUSE_LOGWINDOW
        delete m_oglContext;
        ctxAttrs.Reset();
#endif //__WXMAC__
        ctxAttrs.PlatformDefaults().CoreProfile().OGLVersion(3, 2).EndList();
        m_oglContext = new wxGLContext(this, NULL, &ctxAttrs);
#ifndef __WXMAC__
    }
#endif //__WXMAC__

    if ( !m_oglContext->IsOK() )
    {
        wxMessageBox("This sample needs an OpenGL 3.2 capable driver.\nThe app will end now.",
                     "OpenGL version error", wxOK | wxICON_INFORMATION, this);
        delete m_oglContext;
        m_oglContext = NULL;
    }
    else
    {
#if wxUSE_LOGWINDOW
        wxLogMessage("OpenGL Core Profile 3.2 successfully set.");
#endif // wxUSE_LOGWINDOW
    }

}

MyGLCanvas::~MyGLCanvas()
{
    if ( m_oglContext )
        SetCurrent(*m_oglContext);

    if ( m_oglManager )
    {
        delete m_oglManager;
        m_oglManager = NULL;
    }

    if ( m_oglContext )
    {
        delete m_oglContext;
        m_oglContext = NULL;
    }
}

bool MyGLCanvas::oglInit()
{
    if ( !m_oglContext )
        return false;

    // The current context must be set before we get OGL pointers
    SetCurrent(*m_oglContext);

    // Initialize our OGL pointers
    if ( !myOGLManager::Init() )
    {
        wxMessageBox("Error: Some OpenGL pointer to function failed.",
            "OpenGL initialization error", wxOK | wxICON_INFORMATION, this);
        return false;
    }

    // Create our OGL manager, pass our OGL error handler
    m_oglManager = new myOGLManager(&fOGLErrHandler);

    // Get the GL version for the current OGL context
    wxString sglVer = "\nUsing OpenGL version: ";
    sglVer += wxString::FromUTF8(
                reinterpret_cast<const char *>(m_oglManager->GetGLVersion()) );
    // Also Vendor and Renderer
    sglVer += "\nVendor: ";
    sglVer += wxString::FromUTF8(
                reinterpret_cast<const char *>(m_oglManager->GetGLVendor()) );
    sglVer += "\nRenderer: ";
    sglVer += wxString::FromUTF8(
                reinterpret_cast<const char *>(m_oglManager->GetGLRenderer()) );
    // For the menu "About" info
    m_parent->SetOGLString(sglVer);

    // Load some data into GPU
    m_oglManager->SetShadersAndTriangles();

    // This string will be placed on a face of the pyramid
    int swi = 0, shi = 0; //Image sizes
    wxString stg("wxWidgets");
    // Set the font. Use a big pointsize so as to smoothing edges.
    wxFont font(wxFontInfo(48).Family(wxFONTFAMILY_MODERN));
    if ( !font.IsOk() )
        font = *wxSWISS_FONT;
    wxColour bgrdColo(*wxBLACK);
    wxColour foreColo(160, 0, 200); // Dark purple
    // Build an array with the pixels. Background fully transparent
    unsigned char* sPixels = MyTextToPixels(stg, font, foreColo, bgrdColo, 0,
                                            &swi, &shi);
    // Send it to GPU
    m_oglManager->SetStringOnPyr(sPixels, swi, shi);
    delete[] sPixels; // That memory was allocated at MyTextToPixels

    // This string is placed at left bottom of the window. Its size doesn't
    // change with window size.
    stg = "Rotate the pyramid with\nthe left mouse button";
    font.SetPointSize(14);
    bgrdColo = wxColour(40, 40, 255);
    foreColo = wxColour(*wxWHITE);
    unsigned char* stPixels = MyTextToPixels(stg, font, foreColo, bgrdColo, 80,
                                             &swi, &shi);
    m_oglManager->SetImmutableString(stPixels, swi, shi);
    delete[] stPixels;

    return true;
}

void MyGLCanvas::OnPaint( wxPaintEvent& WXUNUSED(event) )
{
    // This is a dummy, to avoid an endless succession of paint messages.
    // OnPaint handlers must always create a wxPaintDC.
    wxPaintDC dc(this);

    // Avoid painting when we have not yet a size
    if ( m_winHeight < 1 || !m_oglManager )
        return;

    // This should not be needed, while we have only one canvas
    SetCurrent(*m_oglContext);

    // Do the magic
    m_oglManager->Render();

    SwapBuffers();
}

//Note:
// You may wonder why OpenGL initialization was not done at wxGLCanvas ctor.
// The reason is due to GTK+/X11 working asynchronously, we can't call
// SetCurrent() before the window is shown on screen (GTK+ doc's say that the
// window must be realized first).
// In wxGTK, window creation and sizing requires several size-events. At least
// one of them happens after GTK+ has notified the realization. We use this
// circumstance and do initialization then.

void MyGLCanvas::OnSize(wxSizeEvent& event)
{
    event.Skip();

    // If this window is not fully initialized, dismiss this event
    if ( !IsShownOnScreen() )
        return;

    if ( !m_oglManager )
    {
        //Now we have a context, retrieve pointers to OGL functions
        if ( !oglInit() )
            return;
        //Some GPUs need an additional forced paint event
        PostSizeEvent();
    }

    // This is normally only necessary if there is more than one wxGLCanvas
    // or more than one wxGLContext in the application.
    SetCurrent(*m_oglContext);

    // It's up to the application code to update the OpenGL viewport settings.
    const wxSize size = event.GetSize() * GetContentScaleFactor();
    m_winHeight = size.y;
    m_oglManager->SetViewport(0, 0, size.x, m_winHeight);

    // Generate paint event without erasing the background.
    Refresh(false);
}

void MyGLCanvas::OnMouse(wxMouseEvent& event)
{
    event.Skip();

    // GL 0 Y-coordinate is at bottom of the window
    int oglwinY = m_winHeight - event.GetY();

    if ( event.LeftIsDown() )
    {
        if ( ! event.Dragging() )
        {
            // Store positions
            m_oglManager->OnMouseButDown(event.GetX(), oglwinY);
        }
        else
        {
            // Rotation
            m_oglManager->OnMouseRotDragging( event.GetX(), oglwinY );

            // Generate paint event without erasing the background.
            Refresh(false);
        }
    }
}