Алгоритмы растрирования. Алгоритм Брезенхема

/* Simple Windows API program */
 
#include <windows.h>
#include <tchar.h>
 
/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);
 
/*  Make the class name into a global variable  */
//char szClassName[] = "WindowsApp";
static TCHAR szClassName[] = _T("DesktopApp");
static TCHAR szTitle[] = _T("Windows Desktop Guided Tour Application");
 
void setPixel(HWND hWnd, int x, int y, COLORREF& color) {
 
   HDC hdc = GetDC(hWnd);
 
    SetPixel(hdc, x, y, color);
 
    ReleaseDC(hWnd, hdc);
 
    return;
 
    // NEVERREACH //
 
}
 
void Display(HWND hWnd, int x1, int y1, int x2, int y2) {
    // Get window context
    HDC hDc = GetDC(hWnd);
   
    const int deltaX = abs(x2 - x1);
    const int deltaY = abs(y2 - y1);
    const int signX = x1 < x2 ? 1 : -1;
    const int signY = y1 < y2 ? 1 : -1;
    //
    int error = deltaX - deltaY;
    //
    SetPixel(hDc, x2, y2, 0);
    while (x1 != x2 || y1 != y2)
    {
       SetPixel(hDc, x1, y1, 0);
       const int error2 = error * 2;
       //
       if (error2 > -deltaY)
       {
           error -= deltaY;
           x1 += signX;
        }
        if (error2 < deltaX)
        {
            error += deltaX;
            y1 += signY;
        }
    }
}
 
int WINAPI
WinMain(HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nFunsterStil)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */
 
    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof(WNDCLASSEX);
 
    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor(NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH)COLOR_BACKGROUND;
 
    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx(&wincl))
        return 0;
 
    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx(
        0,                   /* Extended possibilites for variation */
        szClassName,         /* Classname */
        szTitle,       /* Title Text */
        WS_OVERLAPPEDWINDOW, /* default window */
        CW_USEDEFAULT,       /* Windows decides the position */
        CW_USEDEFAULT,       /* where the window ends up on the screen */
        544,                 /* The programs width */
        375,                 /* and height in pixels */
        HWND_DESKTOP,        /* The window is a child-window to desktop */
        NULL,                /* No menu */
        hThisInstance,       /* Program Instance handler */
        NULL                 /* No Window Creation data */
        );
 
    /* Make the window visible on the screen */
    ShowWindow(hwnd, nFunsterStil);
 
    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage(&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }
 
    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}
 
 
/*  This function is called by the Windows function DispatchMessage()  */
 
LRESULT CALLBACK
WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {
    case WM_DESTROY:
        PostQuitMessage(0);       /* send a WM_QUIT to the message queue */
        break;
    case WM_PAINT:
        Display(hwnd, 10, 20, 250, 300);
        break;
    default:                      /* for messages that we don't deal with */
        return DefWindowProc(hwnd, message, wParam, lParam);
    }
 
    return 0;
}

        for(int i = 0; i < 12; ++ i)
            Display(250, 300, 250 + 250 * cos((float)i / 2), 300 + 250 * sin((float)i / 2));