open gl code

main.cpp

/**************************
 * Includes
 *
 **************************/

#include <windows.h>
#include <gl/gl.h>
#include <math.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);


/**************************
 * WinMain
 *
 **************************/
 
 
 void DrawCircle(float cx, float cy, float r, int num_segments)
{
    glBegin(GL_LINE_LOOP);
    for(int ii = 0; ii < num_segments; ii++)
    {
        float theta = 2.0f * 3.1415926f * float(ii) / float(num_segments);//get the current angle

        float x = r * cosf(theta);//calculate the x component
        float y = r * sinf(theta);//calculate the y component

        glVertex2f(x + cx, y + cy);//output vertex

    }
    glEnd();
}

void drawFilledCircle(GLfloat x, GLfloat y, GLfloat radius){
	int i;
	int triangleAmount = 1000; //# of triangles used to draw circle
	
	//GLfloat radius = 0.8f; //radius
	GLfloat twicePi = 2.0f * 3.1415926f;
	
	glBegin(GL_TRIANGLE_FAN);
	glVertex2f(x, y); // center of circle
		for(i = 0; i <= triangleAmount;i++) { 
			glVertex2f(
		            x + (radius * cos(i *  twicePi / triangleAmount)), 
			        y + (radius * sin(i * twicePi / triangleAmount))
			);
		}
	glEnd();
}



void drawTriangle(GLfloat x, GLfloat y){
      
    glBegin (GL_TRIANGLES);
    glColor3f (1.0f, 0.0f, 0.0f);   glVertex2f (0.0f, 1.0f);
    glColor3f (0.0f, 1.0f, 0.0f);   glVertex2f (0.87f, -0.5f);
    glColor3f (0.0f, 0.0f, 1.0f);   glVertex2f (-0.87f, -0.5f);
	glEnd();
}


void drawRectangle(GLfloat x, GLfloat y) {
     
    glBegin(GL_QUADS);
    glColor3f (1.0f, 0.0f, 0.0f);   glVertex2f (0.87f, 0.5f);
    glColor3f (0.0f, 1.0f, 0.0f);   glVertex2f (0.87f, -0.5f);
    glColor3f (0.0f, 0.0f, 1.0f);   glVertex2f (-0.87f, -0.5f);
    glColor3f (0.0f, 0.0f, 1.0f);   glVertex2f (-0.87f, 0.5f);
	glEnd();         
}

void drawEllipse(GLfloat xradius, GLfloat yradius)
{
	glBegin(GL_LINE_LOOP);
   const float DEG2RAD = 3.14159/180.0;

	for(int i=0; i < 360; i++)
	{
		float degInRad = i*DEG2RAD;
		glVertex2f(cos(degInRad)*xradius,sin(degInRad)*yradius);
	} 
	glEnd();
}


void drawLine(GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2) {
         glBegin(GL_LINE_LOOP);
         
         glVertex2f(x1, y1);

         glVertex2f(x2, y2);         
     
     glEnd();
}


/*

void drawCube() {
     
     glBegin(GL_QUADS);
	// top
	glColor3f(1.0f, 0.0f, 0.0f);
	glNormal3f(0.0f, 1.0f, 0.0f);
	glVertex3f(-0.5f, 0.5f, 0.5f);
	glVertex3f(0.5f, 0.5f, 0.5f);
	glVertex3f(0.5f, 0.5f, -0.5f);
	glVertex3f(-0.5f, 0.5f, -0.5f);
 
	glEnd();
 
	glBegin(GL_QUADS);
	// front
	glColor3f(0.0f, 1.0f, 0.0f);
	glNormal3f(0.0f, 0.0f, 1.0f);
	glVertex3f(0.5f, -0.5f, 0.5f);
	glVertex3f(0.5f, 0.5f, 0.5f);
	glVertex3f(-0.5f, 0.5f, 0.5f);
	glVertex3f(-0.5f, -0.5f, 0.5f);
 
	glEnd();
 
	glBegin(GL_QUADS);
	// right
	glColor3f(0.0f, 0.0f, 1.0f);
	glNormal3f(1.0f, 0.0f, 0.0f);
	glVertex3f(0.5f, 0.5f, -0.5f);
	glVertex3f(0.5f, 0.5f, 0.5f);
	glVertex3f(0.5f, -0.5f, 0.5f);
	glVertex3f(0.5f, -0.5f, -0.5f);
 
	glEnd();
 
	glBegin(GL_QUADS);
	// left
	glColor3f(0.0f, 0.0f, 0.5f);
	glNormal3f(-1.0f, 0.0f, 0.0f);
	glVertex3f(-0.5f, -0.5f, 0.5f);
	glVertex3f(-0.5f, 0.5f, 0.5f);
	glVertex3f(-0.5f, 0.5f, -0.5f);
	glVertex3f(-0.5f, -0.5f, -0.5f);
 
	glEnd();
 
	glBegin(GL_QUADS);
	// bottom
	glColor3f(0.5f, 0.0f, 0.0f);
	glNormal3f(0.0f, -1.0f, 0.0f);
	glVertex3f(0.5f, -0.5f, 0.5f);
	glVertex3f(-0.5f, -0.5f, 0.5f);
	glVertex3f(-0.5f, -0.5f, -0.5f);
	glVertex3f(0.5f, -0.5f, -0.5f);
 
	glEnd();
 
	glBegin(GL_QUADS);
	// back
	glColor3f(0.0f, 0.5f, 0.0f);
	glNormal3f(0.0f, 0.0f, -1.0f);
	glVertex3f(0.5f, 0.5f, -0.5f);
	glVertex3f(0.5f, -0.5f, -0.5f);
	glVertex3f(-0.5f, -0.5f, -0.5f);
	glVertex3f(-0.5f, 0.5f, -0.5f);
 
	glEnd();     
     
}
*/

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 theta = 0.0f;

    /* register window class */
    wc.style = CS_OWNDC;
    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", "OpenGL Sample", 
      WS_CAPTION | WS_POPUPWINDOW | WS_VISIBLE,
      0, 0, 768, 768,
      NULL, NULL, hInstance, NULL);

    /* enable OpenGL for the window */
    EnableOpenGL (hWnd, &hDC, &hRC);



    /* 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
        {

            glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
            glClear (GL_COLOR_BUFFER_BIT);                     
                        
            /* OpenGL animation code goes here */
            

            glPushMatrix ();
  //          glRotatef (theta, 0.0f, 0.0f, 1.0f);
//            glBegin (GL_TRIANGLES);
    //        glColor3f (1.0f, 0.0f, 0.0f);   glVertex2f (0.0f, 1.0f);
     //       glColor3f (0.0f, 1.0f, 0.0f);   glVertex2f (0.87f, -0.5f);
      //      glColor3f (0.0f, 0.0f, 1.0f);   glVertex2f (-0.87f, -0.5f);
              
//              drawFilledCircle(0, 0, 1);
             //DrawCircle(0, 0, 1, 1);
//             drawTriangle(0, 0);
              // drawRectangle(0, 0);
             // drawEllipse(1, 0.5);
             
              //drawCube();
              drawLine(0, 0, 0.5, 0.5);
        
//            glEnd ();
            glPopMatrix ();

            SwapBuffers (hDC);

            theta += 1.0f;
            Sleep (1);
            
        }
    }
    
   
    /* 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)
{

    switch (message)
    {
    case WM_CREATE:
        return 0;
    case WM_CLOSE:
        PostQuitMessage (0);
        return 0;

    case WM_DESTROY:
        return 0;

    case WM_KEYDOWN:
        switch (wParam)
        {
        case VK_ESCAPE:
            PostQuitMessage(0);
            return 0;
        }
        return 0;

    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.iPixelType = PFD_TYPE_RGBA;
    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);
}