きったんの頭_ん中☆

マンデルブロ集合 | JS版 |
/*
 * Draw Mandelbrot Set in C (Win32API)
 * https://mind.kittttttan.info/c/mandelbrot
 *
 * How to compile with GCC:
 *    $ gcc -mwindows -o mandelbrot mandelbrot.c
 */

#include <windows.h>

#define LIMIT 256
#define ZOOM 128.0
#define WIDTH 384 // (int)ZOOM * 3
#define HEIGHT 414 // WIDTH + 30

int data[WIDTH][HEIGHT];

int lim(double x, double y);
void calc(void);
HWND Create(HINSTANCE hInst);
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
      PSTR lpCmdLine, int nCmdShow) {
  HWND hwnd;
  MSG msg;

  hwnd = Create(hInstance);
  if (hwnd == NULL) { return -1; }

  calc();

  while (GetMessage(&msg, NULL, 0, 0)) {
    DispatchMessage(&msg);
  }

  return msg.wParam;
}

int lim(double x, double y) {
  int i, c;
  double px, py, nx, ny;
  c = 0;
  px = py = 0.0;
  for (i = 0; i < LIMIT; i++) {
    nx = px * px - py * py + x;
    ny = 2.0 * px * py + y;
    if (nx * nx + ny * ny > 4.0) {
      c = i + 1;
      break;
    } else {
      px = nx;
      py = ny;
    }
  }
  if (!c) { c = LIMIT; }
  return c;
}

void calc(void) {
  int i, j;
  for (i = 0; i < WIDTH; ++i) {
    for (j = 0; j < HEIGHT; ++j) {
      data[i][j] = lim(i / ZOOM - 2, j / ZOOM - 1.5);
    }
  }
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp) {
  HDC hdc;
  PAINTSTRUCT ps;
  int i, j, c;

  switch (msg) {
  case WM_DESTROY:
    PostQuitMessage(0);
    return 0;
  case WM_PAINT:
    hdc = BeginPaint(hwnd, &ps);
    for (i = 0; i < WIDTH; ++i) {
      for (j = 0; j < HEIGHT; ++j) {
        if (data[i][j] < LIMIT) {
          c = data[i][j] << 4;
          if (c > 0xff) { c = 0xff; }
        } else {
          c = 0;
        }
        SetPixel(hdc, i, j, RGB(0, 0, c));
      }
    }
    EndPaint(hwnd, &ps);
    return 0;
  }
  return DefWindowProc(hwnd, msg, wp, lp);
}

HWND Create(HINSTANCE hInstance) {
  WNDCLASS winc;

  winc.style = 0;
  winc.lpfnWndProc = WndProc;
  winc.cbClsExtra = winc.cbWndExtra = 0;
  winc.hInstance = hInstance;
  winc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
  winc.hCursor = LoadCursor(NULL, IDC_ARROW);
  winc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
  winc.lpszMenuName = NULL;
  winc.lpszClassName = TEXT("Main");

  if (!RegisterClass(&winc)) { return NULL; }

  return CreateWindow(
      TEXT("Main"), TEXT("Mandelbrot"),
      WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_VISIBLE,
      CW_USEDEFAULT, CW_USEDEFAULT,
      WIDTH, HEIGHT,
      NULL, NULL, hInstance, NULL);
}
きったんの頭ん中☆

きったんの頭_ん中☆
