Example of the Minimal Win32 & OpenGL program

Published July 25, 1999 by Unknown Author, posted by Myopic Rhino
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/* An example of the minimal Win32 & OpenGL program. It only works in
16 bit color modes or higher (since it doesn't create a
palette). */


#include /* must include this before GL/gl.h */
#include /* OpenGL header file */
#include /* OpenGL utilities header file */
#include


void
display()
{
/* rotate a triangle around */
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_TRIANGLES);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex2i(0, 1);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex2i(-1, -1);
glColor3f(0.0f, 0.0f, 1.0f);
glVertex2i(1, -1);
glEnd();
glFlush();
}


LONG WINAPI
WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
static PAINTSTRUCT ps;

switch(uMsg) {
case WM_PAINT:
display();
BeginPaint(hWnd, &ps);
EndPaint(hWnd, &ps);
return 0;

case WM_SIZE:
glViewport(0, 0, LOWORD(lParam), HIWORD(lParam));
PostMessage(hWnd, WM_PAINT, 0, 0);
return 0;

case WM_CHAR:
switch (wParam) {
case 27: /* ESC key */
PostQuitMessage(0);
break;
}
return 0;

case WM_CLOSE:
PostQuitMessage(0);
return 0;
}

return DefWindowProc(hWnd, uMsg, wParam, lParam);
}

HWND
CreateOpenGLWindow(char* title, int x, int y, int width, int height,
BYTE type, DWORD flags)
{
int pf;
HDC hDC;
HWND hWnd;
WNDCLASS wc;
PIXELFORMATDESCRIPTOR pfd;
static HINSTANCE hInstance = 0;

/* only register the window class once - use hInstance as a flag. */
if (!hInstance) {
hInstance = GetModuleHandle(NULL);
wc.style = CS_OWNDC;
wc.lpfnWndProc = (WNDPROC)WindowProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(NULL, IDI_WINLOGO);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = NULL;
wc.lpszMenuName = NULL;
wc.lpszClassName = "OpenGL";

if (!RegisterClass(&wc)) {
MessageBox(NULL, "RegisterClass() failed: "
"Cannot register window class.", "Error", MB_OK);
return NULL;
}
}

hWnd = CreateWindow("OpenGL", title, WS_OVERLAPPEDWINDOW |
WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
x, y, width, height, NULL, NULL, hInstance, NULL);

if (hWnd == NULL) {
MessageBox(NULL, "CreateWindow() failed: Cannot create a window.",
"Error", MB_OK);
return NULL;
}

hDC = GetDC(hWnd);

/* there is no guarantee that the contents of the stack that become
the pfd are zeroed, therefore _make sure_ to clear these bits. */
memset(&pfd, 0, sizeof(pfd));
pfd.nSize = sizeof(pfd);
pfd.nVersion = 1;
pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | flags;
pfd.iPixelType = type;
pfd.cColorBits = 32;

pf = ChoosePixelFormat(hDC, &pfd);
if (pf == 0) {
MessageBox(NULL, "ChoosePixelFormat() failed: "
"Cannot find a suitable pixel format.", "Error", MB_OK);
return 0;
}

if (SetPixelFormat(hDC, pf, &pfd) == FALSE) {
MessageBox(NULL, "SetPixelFormat() failed: "
"Cannot set format specified.", "Error", MB_OK);
return 0;
}

DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd);

ReleaseDC(hWnd, hDC);

return hWnd;
}

int APIENTRY
WinMain(HINSTANCE hCurrentInst, HINSTANCE hPreviousInst,
LPSTR lpszCmdLine, int nCmdShow)
{
HDC hDC; /* device context */
HGLRC hRC; /* opengl context */
HWND hWnd; /* window */
MSG msg; /* message */

hWnd = CreateOpenGLWindow("minimal", 0, 0, 256, 256, PFD_TYPE_RGBA, 0);
if (hWnd == NULL)
exit(1);

hDC = GetDC(hWnd);
hRC = wglCreateContext(hDC);
wglMakeCurrent(hDC, hRC);

ShowWindow(hWnd, nCmdShow);

while(GetMessage(&msg, hWnd, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}

wglMakeCurrent(NULL, NULL);
ReleaseDC(hWnd, hDC);
wglDeleteContext(hRC);
DestroyWindow(hWnd);

return msg.wParam;
}

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An example of the minimal Win32 & OpenGL program. It only works in 16 bit color modes or higher (since it doesn't create a palette).

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