重新定义OpenGL示例中的WinMain错误

Redefinition of WinMain Error in OpenGL example

本文关键字：WinMain 错误 OpenGL 新定义 定义      更新时间：2023-10-16

我正试图通过这个例子与OpenGL取得联系:

#include <windows.h>
#include <GL/GL.h>
#pragma comment (lib, "opengl32.lib")
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
int WinMain( __in HINSTANCE hInstance, __in_opt HINSTANCE hPrevInstance, __in_opt LPSTR lpCmdLine, __in int nShowCmd )
{
    MSG msg          = {0};
    WNDCLASS wc      = {0}; 
    wc.lpfnWndProc   = WndProc;
    wc.hInstance     = hInstance;
    wc.hbrBackground = (HBRUSH)(COLOR_BACKGROUND);
    wc.lpszClassName = L"oglversionchecksample";
    wc.style = CS_OWNDC;
    if( !RegisterClass(&wc) )
        return 1;
    CreateWindowW(wc.lpszClassName,L"openglversioncheck",WS_OVERLAPPEDWINDOW|WS_VISIBLE,0,0,640,480,0,0,hInstance,0);
    while( GetMessage( &msg, NULL, 0, 0 ) > 0 )
        DispatchMessage( &msg );
    return 0;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
    case WM_CREATE:
        {
        PIXELFORMATDESCRIPTOR pfd =
        {
            sizeof(PIXELFORMATDESCRIPTOR),
            1,
            PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,    //Flags
            PFD_TYPE_RGBA,            //The kind of framebuffer. RGBA or palette.
            32,                        //Colordepth of the framebuffer.
            0, 0, 0, 0, 0, 0,
            0,
            0,
            0,
            0, 0, 0, 0,
            24,                        //Number of bits for the depthbuffer
            8,                        //Number of bits for the stencilbuffer
            0,                        //Number of Aux buffers in the framebuffer.
            PFD_MAIN_PLANE,
            0,
            0, 0, 0
        };
        HDC ourWindowHandleToDeviceContext = GetDC(hWnd);
        int  letWindowsChooseThisPixelFormat;
        letWindowsChooseThisPixelFormat = ChoosePixelFormat(ourWindowHandleToDeviceContext, &pfd); 
        SetPixelFormat(ourWindowHandleToDeviceContext,letWindowsChooseThisPixelFormat, &pfd);
        HGLRC ourOpenGLRenderingContext = wglCreateContext(ourWindowHandleToDeviceContext);
        wglMakeCurrent (ourWindowHandleToDeviceContext, ourOpenGLRenderingContext);
        MessageBoxA(0,(char*)glGetString(GL_VERSION), "OPENGL VERSION",0);
        wglDeleteContext(ourOpenGLRenderingContext);
        PostQuitMessage(0);
        }
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

我正在使用最新版本的Code::Blocks (v13.12)与MinGW-TDM-GCC-4.8.1
在链接器设置中，我链接了libopengl32。a，我使用了MinGW发行版中的windows.h和gl -头文件。

但是我得到这个错误:

main.cpp|4|warning: ignoring #pragma comment  [-Wunknown-pragmas]|
main.cpp|8|error: 'int WinMain' redeclared as different kind of symbol|
codeblocksmingwincludewinbase.h|1251|error: previous declaration of 'int WinMain(HINSTANCE, HINSTANCE, LPSTR, int)'|
main.cpp|8|error: '__in' was not declared in this scope|
main.cpp|8|error: '__in_opt' was not declared in this scope|
main.cpp|8|error: '__in_opt' was not declared in this scope|
main.cpp|8|error: '__in' was not declared in this scope|

我错过什么了吗?或者这个例子只在使用Visual Studio时有效(就像pragma看起来的那样)?

编辑

我把所有的东西都剪掉了(没有opengl的东西)，只有win header和它的WinMain，有同样的错误。

然后我用它的标准main(见这里)替换了WinMain 

int main()
{
    HINSTANCE hInstance = GetModuleHandle( NULL );
    HINSTANCE hPrevInstance = 0;
    LPSTR lpCmdLine = NULL;
    int nShowCmd = 0;
    ...same as before
    return 0;
}

和它编译后没有错误，我也链接到libgdi32。，但是它只显示一个空命令提示符。

编辑2

我删除了宽字符串(L""和CreateWindowW到CreateWindow)，现在它工作了..

我猜mingw不喜欢所有MSVC特定的东西，删除#pragma comment和所有__in等。我认为，既然mingw不能解决那些它不能匹配WinMain与它所拥有的定义和失败。基本上把开头改写成这样:

#include <windows.h>
#include <GL/GL.h>
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
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