I’ve just started to learn openGL. I bought this big thick book that should show me how to make it all work. The problem is that I can’t get this first script to work. Aparently, it’s supposed to display a rotating triangle in a Windows display. This is what I have. Any help will be really helpful
// Includes
#include <windows.h>
#include <gl/gl.h>
// Function Declarations
LRESULT CALLBACK WndProc( HWND hWnd,
UINT message,
WPARAM wParam,
LPARAM lParam );
VOID EnableOpenGL( HWND hWnd, HDC * hDC, HGLRC * hRC );
VOID DisableOpenGL( HWND hWnd, HDC hDC, HGLRC hRC );
HDC g_HDC;
// WinMain
int WINAPI WinMain( HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int iCmdShow )
{
WNDCLASS wc;
HWND hWnd;
HDC hDC;
HGLRC hRC;
MSG msg;
BOOL bQuit = FALSE;
float angle = 0.0f;
// register window class
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon( NULL, IDI_APPLICATION );
wc.hCursor = LoadCursor( NULL, IDC_ARROW );
wc.hbrBackground = (HBRUSH)GetStockObject( BLACK_BRUSH );
wc.lpszMenuName = NULL;
wc.lpszClassName = "GLSample";
RegisterClass( &wc );
// create main window
hWnd = CreateWindow( "GLSample",
"My OpenGL Program",
WS_CAPTION | WS_POPUPWINDOW | WS_VISIBLE,
100, 100, 400, 400,
NULL, NULL, hInstance, NULL );
ShowWindow(hWnd, SW_SHOW);
UpdateWindow(hWnd);
// program main loop
while ( !bQuit )
{
// check for messages
if ( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) )
{
// handle or dispatch messages
if ( msg.message == WM_QUIT )
{
bQuit = TRUE;
}
else
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
}
else
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
angle = angle + 0.1f;
if (angle >= 360.0f)
angle = 0.0f;
glTranslatef(0.0f, 0.0f, -5.0f);
glRotatef(angle, 0.0f, 0.0f, 1.0f);
glColor3f(1.0f, 0.0f, 0.0f);
glBegin(GL_TRIANGLES);
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(1.0f, 0.0f, 0.0f);
glVertex3f(1.0f, 1.0f, 0.0f);
glEnd();
SwapBuffers(g_HDC);
}
}
// shutdown OpenGL
DisableOpenGL( hWnd, hDC, hRC );
// destroy the window explicitly
DestroyWindow( hWnd );
return msg.wParam;
}
// Window Procedure
LRESULT CALLBACK WndProc( HWND hWnd,
UINT message,
WPARAM wParam,
LPARAM lParam )
{
static HGLRC hRC;
static HDC hDC;
switch( message )
{
case WM_CREATE:
hDC = GetDC(hWnd);
g_HDC = hDC;
// enable OpenGL for the window
EnableOpenGL( hWnd, &hDC, &hRC );
hRC = wglCreateContext(hDC);
wglMakeCurrent(hDC, hRC);
return 0;
break;
case WM_CLOSE:
wglMakeCurrent(hDC, NULL);
wglDeleteContext(hRC);
PostQuitMessage( 0 );
return 0;
break;
case WM_KEYDOWN:
switch ( wParam )
{
case VK_ESCAPE:
PostQuitMessage( 0 );
break;
}
break;
default:
return DefWindowProc( hWnd, message, wParam, lParam );
}
}
// Enable OpenGL
VOID EnableOpenGL( HWND hWnd, HDC * hDC, HGLRC * hRC )
{
PIXELFORMATDESCRIPTOR pfd;
int iFormat;
// get the device context (DC)
*hDC = GetDC( hWnd );
// set the pixel format for the DC
ZeroMemory( &pfd, sizeof( pfd ) );
pfd.nSize = sizeof( pfd );
pfd.nVersion = 1;
pfd.dwFlags = PFD_DRAW_TO_WINDOW |
PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER;
pfd.cColorBits = 24;
pfd.cDepthBits = 16;
pfd.iLayerType = PFD_MAIN_PLANE;
iFormat = ChoosePixelFormat( *hDC, &pfd );
SetPixelFormat( *hDC, iFormat, &pfd );
// create and enable the render context (RC)
*hRC = wglCreateContext( *hDC );
wglMakeCurrent( *hDC, *hRC );
}
// Disable OpenGL
VOID DisableOpenGL( HWND hWnd, HDC hDC, HGLRC hRC )
{
wglMakeCurrent( NULL, NULL );
wglDeleteContext( hRC );
ReleaseDC( hWnd, hDC );
}