I am trying to make a game engine that can switch between editor mode(wxWidget) and normal WinMain mode. That is to say, I will pass the hWnd of a wxWidget GLCanvas over to create a GL Window so that it will render stuffs inside the GLCanvas. However, it prompts an error when I try to render a triangle on screen. In WinMain mode, it is fine:
However, if I switch it to wxWidget mode, it will prompt an error:
If I disable this line :
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glDrawArrays(GL_TRIANGLES, 0, 3);
Hopefully someone can have a solution to this!! Thanks!!
Some Code:
GLCanvas:
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HWND g_hWnd;
TestGLCanvas::TestGLCanvas(wxWindow *parent,
wxWindowID id,
const wxPoint& pos,
const wxSize& size,
long style,
const wxString& name)
: wxGLCanvas(parent, id, NULL, pos, size,
style | wxFULL_REPAINT_ON_RESIZE, name)
{
// Explicitly create a new rendering context instance for this canvas.
m_Init = false;
g_hWnd = (HWND)GetHWND();
m_glRC = new wxGLContext(this);
}
void TestGLCanvas::OnPaint(wxPaintEvent& WXUNUSED(event))
{
// must always be here
wxPaintDC dc(this);
if (!m_Init)
{
CreateGLWindow(L"Wx OpenL", 640, 480, 16, false, g_hWnd);
gEngine = new GraphicEngine();
m_Init = true;
SetCurrent(*m_glRC);
}
else
{
ResetProjectionMode();
gEngine->Render();
//DrawGLScene(); // Draw The Scene
glFlush();
SwapBuffers(); // Swap Buffers (Double Buffering)
}
}
void TestGLCanvas::OnIdle(wxIdleEvent& event WXUNUSED(event))
{
event.RequestMore(true);
gEngine->Render();
//DrawGLScene(); // Draw The Scene
SwapBuffers(); // Swap Buffers (Double Buffering)
}
void TestGLCanvas::OnSize(wxSizeEvent& WXUNUSED(event))
{
// Reset the OpenGL view aspect.
// This is OK only because there is only one canvas that uses the context.
// See the cube sample for that case that multiple canvases are made current with one context.
ResetProjectionMode();
}
void TestGLCanvas::ResetProjectionMode()
{
if (!IsShownOnScreen())
return;
// This is normally only necessary if there is more than one wxGLCanvas
// or more than one wxGLContext in the application.
SetCurrent(*m_glRC);
int w, h;
GetClientSize(&w, &h);
// It's up to the application code to update the OpenGL viewport settings.
// In order to avoid extensive context switching, consider doing this in
// OnPaint() rather than here, though.
glViewport(0, 0, (GLint)w, (GLint)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//gluPerspective(45.0f, (GLfloat)w / h, 1.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
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BOOL CreateGLWindow(LPCWSTR title, int width, int height, int bits, bool fullscreenflag, HWND hWnd2)
{
hWnd = hWnd2 ? hWnd2 : hWnd;
GLuint PixelFormat; // Holds The Results After Searching For A Match
WNDCLASS wc; // Windows Class Structure
DWORD dwExStyle; // Window Extended Style
DWORD dwStyle; // Window Style
RECT WindowRect; // Grabs Rectangle Upper Left / Lower Right Values
WindowRect.left = (long)0; // Set Left Value To 0
WindowRect.right = (long)width; // Set Right Value To Requested Width
WindowRect.top = (long)0; // Set Top Value To 0
WindowRect.bottom = (long)height; // Set Bottom Value To Requested Height
fullscreen = fullscreenflag; // Set The Global Fullscreen Flag
hInstance = GetModuleHandle(NULL); // Grab An Instance For Our Window
wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Size, And Own DC For Window.
wc.lpfnWndProc = (WNDPROC)WndProc; // WndProc Handles Messages
wc.cbClsExtra = 0; // No Extra Window Data
wc.cbWndExtra = 0; // No Extra Window Data
wc.hInstance = hInstance; // Set The Instance
wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load The Default Icon
wc.hCursor = LoadCursor(NULL, IDC_ARROW); // Load The Arrow Pointer
wc.hbrBackground = NULL; // No Background Required For GL
wc.lpszMenuName = NULL; // We Don't Want A Menu
wc.lpszClassName = L"OpenGL"; // Set The Class Name
if (!RegisterClass(&wc)) // Attempt To Register The Window Class
{
MessageBox(NULL, L"Failed To Register The Window Class.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (fullscreen) // Attempt Fullscreen Mode?
{
DEVMODE dmScreenSettings; // Device Mode
memset(&dmScreenSettings, 0, sizeof(dmScreenSettings)); // Makes Sure Memory's Cleared
dmScreenSettings.dmSize = sizeof(dmScreenSettings); // Size Of The Devmode Structure
dmScreenSettings.dmPelsWidth = width; // Selected Screen Width
dmScreenSettings.dmPelsHeight = height; // Selected Screen Height
dmScreenSettings.dmBitsPerPel = bits; // Selected Bits Per Pixel
dmScreenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT;
// Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.
if (ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL)
{
// If The Mode Fails, Offer Two Options. Quit Or Use Windowed Mode.
if (MessageBox(NULL, L"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?", L"NeHe GL", MB_YESNO | MB_ICONEXCLAMATION) == IDYES)
{
fullscreen = FALSE; // Windowed Mode Selected. Fullscreen = FALSE
}
else
{
// Pop Up A Message Box Letting User Know The Program Is Closing.
MessageBox(NULL, L"Program Will Now Close.", L"ERROR", MB_OK | MB_ICONSTOP);
return FALSE; // Return FALSE
}
}
}
if (fullscreen) // Are We Still In Fullscreen Mode?
{
dwExStyle = WS_EX_APPWINDOW; // Window Extended Style
dwStyle = WS_POPUP; // Windows Style
ShowCursor(FALSE); // Hide Mouse Pointer
}
else
{
dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // Window Extended Style
dwStyle = WS_OVERLAPPEDWINDOW; // Windows Style
}
AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle); // Adjust Window To True Requested Size
// Create The Window
if (!(hWnd = CreateWindowEx(dwExStyle, // Extended Style For The Window
L"OpenGL", // Class Name
title, // Window Title
dwStyle | // Defined Window Style
WS_CLIPSIBLINGS | // Required Window Style
WS_CLIPCHILDREN, // Required Window Style
0, 0, // Window Position
WindowRect.right - WindowRect.left, // Calculate Window Width
WindowRect.bottom - WindowRect.top, // Calculate Window Height
NULL, // No Parent Window
NULL, // No Menu
hInstance, // Instance
NULL))) // Dont Pass Anything To WM_CREATE
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Window Creation Error.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be
{
sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor
1, // Version Number
PFD_DRAW_TO_WINDOW | // Format Must Support Window
PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
PFD_DOUBLEBUFFER, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
bits, // Select Our Color Depth
0, 0, 0, 0, 0, 0, // Color Bits Ignored
0, // No Alpha Buffer
0, // Shift Bit Ignored
0, // No Accumulation Buffer
0, 0, 0, 0, // Accumulation Bits Ignored
16, // 16Bit Z-Buffer (Depth Buffer)
0, // No Stencil Buffer
0, // No Auxiliary Buffer
PFD_MAIN_PLANE, // Main Drawing Layer
0, // Reserved
0, 0, 0 // Layer Masks Ignored
};
if (!(hDC = GetDC(hWnd))) // Did We Get A Device Context?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Can't Create A GL Device Context.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) // Did Windows Find A Matching Pixel Format?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Can't Find A Suitable PixelFormat.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!SetPixelFormat(hDC, PixelFormat, &pfd)) // Are We Able To Set The Pixel Format?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Can't Set The PixelFormat.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!(hRC = wglCreateContext(hDC))) // Are We Able To Get A Rendering Context?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Can't Create A GL Rendering Context.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!wglMakeCurrent(hDC, hRC)) // Try To Activate The Rendering Context
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Can't Activate The GL Rendering Context.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!hWnd2)
ShowWindow(hWnd, SW_SHOW); // Show The Window
SetForegroundWindow(hWnd); // Slightly Higher Priority
SetFocus(hWnd); // Sets Keyboard Focus To The Window
ReSizeGLScene(width, height); // Set Up Our Perspective GL Screen
if (!InitGL()) // Initialize Our Newly Created GL Window
{
KillGLWindow(); // Reset The Display
MessageBox(NULL, L"Initialization Failed.", L"ERROR", MB_OK | MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
return TRUE; // Success
}
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// This will identify our vertex buffer
GLuint vertexbuffer;
GraphicEngine::GraphicEngine()
{
/* GL3W Initialization */
if (gl3wInit())
{
std::cerr << "Failed to initialize OpenGL.\n";
exit(1);
}
if (!gl3wIsSupported(3, 3))
{
std::cerr << "OpenGL 3.3 not supported.\n";
exit(1);
}
std::cout << "OpenGL version: " << glGetString(GL_VERSION) << "\n";
std::cout << "GLSL version : " << glGetString(GL_SHADING_LANGUAGE_VERSION) << "\n";
SetUp();
}
GraphicEngine::~GraphicEngine()
{
}
void GraphicEngine::SetUp()
{
static const GLfloat g_vertex_buffer_data[] = {
-1.0f, -1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
};
// Generate 1 buffer, put the resulting identifier in vertexbuffer
glGenBuffers(1, &vertexbuffer);
// The following commands will talk about our 'vertexbuffer' buffer
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
// Give our vertices to OpenGL.
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
}
void GraphicEngine::Render()
{
// 1rst attribute buffer : vertices
glClearColor(1.0f, 0.0f, 0.0f, 0.5f); // Black Background
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(
0, // attribute 0. No particular reason for 0, but must match the layout in the shader.
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
// Draw the triangle !
glDrawArrays(GL_TRIANGLES, 0, 3); // Starting from vertex 0; 3 vertices total -> 1 triangle
glDisableVertexAttribArray(0);
}