mandel.c

mandel.c

#include <windows.h>

#define W 640
#define H 400

const double xCentre = -0.75;
const double yCentre = +0.0;
const int    nx      = W;
const int    ny      = H;

const double dxy     = 0.005;

#define UCHAR_MAX 255

void draw_fractal(HDC hdc)
{
    double cx, cy;
    double zx, zy, new_zx;
    unsigned char n;
    int i, j;

    for (j = 0; j < ny; j++)
    {
        cy = yCentre + (j - ny / 2) * dxy;
        for (i = 0; i < nx; i++)
        {
            cx = xCentre + (i - nx / 2) * dxy;
            zx = 0.0;
            zy = 0.0;
            n = 0;
            while ((zx * zx + zy * zy < 4.0) && (n != UCHAR_MAX))
            {
                new_zx = zx * zx - zy * zy + cx;
                zy = 2.0 * zx * zy + cy;
                zx = new_zx;
                n++;
            }
            UINT col;
            n -= 255;
            if (n < UCHAR_MAX/2-1)
                col = RGB(n*6, n*2, n*8);
            else
                col = RGB(255, n/10, n/2);

            SetPixel(hdc, i, j, col);
        }
    }
}


HWND g_hWnd;

LRESULT CALLBACK WinProc(HWND hWnd,UINT msg, WPARAM wParam,LPARAM lParam)
{
    HDC hDc;
    PAINTSTRUCT pt;

    switch (msg) {
        case WM_PAINT:
            hDc = GetDC(hWnd);
            BeginPaint(hWnd,&pt);
            draw_fractal(hDc);
            EndPaint(hWnd, &pt);
            ReleaseDC(hWnd, hDc);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        
        default:
            return DefWindowProc(hWnd, msg, wParam, lParam);
    }
    return 0;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
    WNDCLASS wc;
    MSG msg;

    ZeroMemory(&wc, sizeof(wc));
    wc.style = CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WinProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDC_ICON);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH) GetStockObject(COLOR_WINDOW);
    wc.lpszMenuName = NULL;

    wc.lpszClassName = "GDI_TEST";
    if (!RegisterClass(&wc))
        return 0;

    g_hWnd = CreateWindow("GDI_TEST", "Foo", WS_OVERLAPPED | WS_SYSMENU,
        0, 0, W, H, NULL, NULL, hInstance, NULL);

    if (!g_hWnd)
        return 0;

    ShowWindow(g_hWnd, SW_SHOW);

    while (GetMessage(&msg, g_hWnd, 0, 0) > 0)
    {
        if (msg.message == WM_QUIT)
            return msg.wParam;
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

int foo()
{
    WinMain(NULL, NULL, NULL, 0);
}