OpenGl 기본 창 생성

프로젝트 생성 후 다음 파일을 작성한다.
프로젝트 Property -> Linker ->Input 에서 opengl32.lib glu32.lib glut32.lib 을 Additonal Dependencies에 추가해 준다.

#include <windows.h>

#include <gl/gl.h>

#include <gl/glu.h>

// global variables

char *szClassName = "Computer Graphics";

HWND MyWND = 0;

HDC MyDC;

HGLRC MyRC;

LRESULT CALLBACK WndProc( HWND, UINT, WPARAM, LPARAM );

bool bSetupPixelFormat(void);

void Resize(const int cx, const int cy);

void DrawScene(void);

/*

* WinMain

*/

int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE, LPSTR, int nShowCmd )

{

// Registers the window class

WNDCLASS wc;

wc.style = CS_HREDRAW | CS_VREDRAW;

wc.lpfnWndProc = (WNDPROC)WndProc;

wc.cbClsExtra = 0;

wc.cbWndExtra = 0;

wc.hInstance = hInstance;

wc.hIcon = LoadIcon( hInstance, IDI_APPLICATION );

wc.hCursor = LoadCursor( 0, IDC_ARROW );

wc.hbrBackground = (HBRUSH)GetStockObject( WHITE_BRUSH );

wc.lpszMenuName = NULL;

wc.lpszClassName = szClassName;

RegisterClass(&wc);

// Create the main window

MyWND = CreateWindow( szClassName, 

"Simple OpenGL Example", 

WS_OVERLAPPEDWINDOW, 

CW_USEDEFAULT, 

CW_USEDEFAULT, 

CW_USEDEFAULT, 

CW_USEDEFAULT, 

0, 

0, 

hInstance, 

0 );

// Make sure that window was created 

if( !MyWND )

return false;

ShowWindow( MyWND, nShowCmd );

UpdateWindow( MyWND );

// Main message loop

MSG msg;

while( GetMessage( &msg, 0, 0, 0 ) ) 

{

TranslateMessage( &msg );

DispatchMessage (&msg );

}

UnregisterClass( szClassName, wc.hInstance );

return msg.wParam;

}

/*

* WndProc: to process messages for the main window

*/

LRESULT CALLBACK WndProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )

{

RECT rect;

switch( msg ) 

{

case WM_CREATE: 

// Initialize for the OpenGL rendering

MyDC = GetDC(hWnd); 

if( !bSetupPixelFormat() ) 

PostQuitMessage (0); 

MyRC = wglCreateContext(MyDC); 

wglMakeCurrent(MyDC, MyRC); 

break; 

        // 창 크기 변경시

case WM_SIZE: 

GetClientRect(hWnd, &rect); 

Resize(rect.right, rect.bottom); 

                // 창을 다시 그려준다.

InvalidateRect(hWnd, NULL, FALSE);

break; 

case WM_DESTROY:

// Destroy all about OpenGL

if( MyRC ) 

wglDeleteContext(MyRC); 

if( MyDC ) 

ReleaseDC(hWnd, MyDC); 

PostQuitMessage(0);

break;

case WM_PAINT:

DrawScene();

ValidateRect(hWnd, NULL);

break;

case WM_KEYDOWN:

if( wParam == VK_ESCAPE ) 

{

DestroyWindow( MyWND );

}

break;

default:

return DefWindowProc( hWnd, msg, wParam, lParam );

}

return 0;

}

/*

* bSetupPixelFormat : to setup the format of pixel for OpenGL

*/

bool bSetupPixelFormat(void) 

{ 

PIXELFORMATDESCRIPTOR pfd; 

int pixelformat; 

pfd.nSize= sizeof( PIXELFORMATDESCRIPTOR ); 

pfd.nVersion= 1; 

pfd.dwFlags= PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL; 

pfd.dwLayerMask= PFD_MAIN_PLANE; 

pfd.iPixelType= PFD_TYPE_RGBA; 

pfd.cColorBits= 24;

pfd.cDepthBits= 16; 

pfd.cAccumBits= 0; 

pfd.cStencilBits= 0;

if( (pixelformat= ChoosePixelFormat( MyDC, &pfd ))==0 ) { 

MessageBox( NULL, "ChoosePixelFormat failed", "Error", MB_OK ); 

return false; 

} 

if( SetPixelFormat( MyDC, pixelformat, &pfd )==false ) { 

MessageBox( NULL, "SetPixelFormat failed", "Error", MB_OK ); 

return false; 

}

return true; 

}

/*

* Resize : to re-initialize 

*/

void Resize(const int cx, const int cy) 

{ 

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

glViewport(0,0,cx,cy);

// 2D orthographic viewing

gluOrtho2D(0, 500, 0, 500);

return;

}    

/*

* DrawScene : to draw a scene

*/

void DrawScene(void)

{

glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

glClear(GL_COLOR_BUFFER_BIT);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();
 

// 사각형

glColor3f(0.0f, 1.0f, 0.0f);

glBegin(GL_POLYGON);

       // openGL은 오른손 좌표계와 데카르트 좌표계를 사용하여
       //  좌측 하단부터 0, 0 으로 시작한다.

glVertex2f(100, 100);

glVertex2f(100, 200);

glVertex2f(200, 200);

glVertex2f(200, 100);

glEnd();

glFlush();

return;

}