Matrix Digital Rain

rain.cpp

#include <stdlib.h>
#include <windows.h>
#include <objidl.h>
#include <gdiplus.h>

using namespace Gdiplus;

wchar_t* characters =
    //Hiragana
	L"あいうえおかきくけこさしすせそたちつてとなにぬねのはひふへほまみむめもや"
	L"ゆよらりるれろわゐゑをんがぎぐげござじずぜぞだぢどばびぶべぼぱぴぷぺぽ"
	//Katakana
	L"アイウエオカキクケコガギグゲゴサシスセソザジズゼゾタチツテトダヂヅデドナ"
	L"ニヌネノハヒフヘホバビブベボパピプペポマミムメモヤユヨラリルレロワヰヱヲン"
	//80 most common japanese kanji
	L"一右雨円王音下火花学気九休金空月犬見五口校左三山子四糸字耳七車手十出女小上森人水"
	L"正生青夕石赤千川先早足村大男中虫町天田土二日入年白八百文木本名目立力林六引雲遠何";

int charlen = 224;

int width = 1440;
int height = 900;
int cw = (int) (width / 12.0);
int ch = (int) (height / 12.0);

int decay = 6; // 2.5%
int fill_start = 102; //40%
float fill_rate = 0.06; //6%
float flip_rate = 0.002; //0.2%
int tick_time = 105; //TODO implement this eventually

wchar_t *data; //character to display
int *path;

wchar_t getRandChar() {
	return characters[rand() % charlen];
}

void setupSimulation() {
	srand(time(NULL));

	data = new wchar_t[cw * ch];
	path = new int[cw * ch];

	//initialize
	for (int i = 0; i < cw * ch; ++i) {
		data[i] = getRandChar();
		path[i] = 0;
	}
}

void update() {
	for (int i = cw * ch - 1; i >= 0; --i) {
		if (i + cw < cw * ch) {
			if (path[i] == 255) {
				path[i + cw] = 255;
				data[i + cw] = getRandChar();
			}
		}
		if (path[i] > 64 && rand() < flip_rate * RAND_MAX) {
			data[i] = getRandChar();
		}
		if (path[i] > decay) {
			path[i] -= decay;
		} else {
			path[i] = 0;
		}
		if (i < cw && path[i] <= fill_start) {
			if (rand() < fill_rate * RAND_MAX) {
				path[i] = 255;
				data[i] = getRandChar();
			}
		}
	}
}

void destroySimulation() {
	delete data;
	delete path;
}

VOID OnPaint(HDC hdc) {
	Graphics gx(hdc);

	SolidBrush black(Color(0, 0, 0));
	gx.FillRectangle(&black, 0, 0, 800, 600);

	Font font(L"MS PGothic", 10);

	int y = 0;
	for (int i = 0; i < cw * ch; ++i) {
		SolidBrush brush(Color(0, path[i], 0));
		PointF p((i % cw) * 12 + 1, y);

		gx.DrawString(&data[i], 1, &font, p, &brush);

		if (i % cw == cw - 1)
			y += 12;
	}
}

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

INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, PSTR, INT iCmdShow) {
	setupSimulation();

	HWND hWnd;
	MSG msg;
	WNDCLASS wndClass;
	GdiplusStartupInput gdiplusStartupInput;
	ULONG_PTR gdiplusToken;

	// Initialize GDI+.
	GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

	wndClass.style = CS_HREDRAW | CS_VREDRAW;
	wndClass.lpfnWndProc = WndProc;
	wndClass.cbClsExtra = 0;
	wndClass.cbWndExtra = 0;
	wndClass.hInstance = hInstance;
	wndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION );
	wndClass.hCursor = LoadCursor(NULL, IDC_ARROW );
	wndClass.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
	wndClass.lpszMenuName = NULL;
	wndClass.lpszClassName = TEXT("Matrix Digital Rain");

	RegisterClass(&wndClass);

	int dwStyle = WS_MINIMIZEBOX | WS_CAPTION | WS_SYSMENU;
	int dwExStyle = 0L;

	RECT size = { 0, 0, width, height };

	AdjustWindowRectEx(&size, dwStyle, false, dwExStyle);

	hWnd = CreateWindowEx(dwExStyle, TEXT("Matrix Digital Rain"), // window class name
			TEXT("Matrix Digital Rain"),   // window caption
			dwStyle,   // window style
			CW_USEDEFAULT,   // initial x position
			CW_USEDEFAULT,   // initial y position
			size.right - size.left,   // initial x size
			size.bottom - size.top,   // initial y size
			NULL,   // parent window handle
			NULL,   // window menu handle
			hInstance,   // program instance handle
			NULL);   // creation parameters

	ShowWindow(hWnd, iCmdShow);
	UpdateWindow(hWnd);

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

	GdiplusShutdown(gdiplusToken);
	destroySimulation();

	return msg.wParam;
}  // WinMain

#define ID_TIMER 1

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
		LPARAM lParam) {
	switch (message) {
	case WM_CREATE:
		SetTimer(hWnd, ID_TIMER, tick_time, NULL);
		return 0;
	case WM_ERASEBKGND:
		return 0;
	case WM_PAINT: {
		PAINTSTRUCT ps;
		HDC hdc = BeginPaint(hWnd, &ps);
		HDC memDC = CreateCompatibleDC(hdc);
		HBITMAP memBM = CreateCompatibleBitmap(hdc, width, height);
		SelectObject(memDC, memBM);
		OnPaint(memDC);
		BitBlt(hdc, 0, 0, width, height, memDC, 0, 0, SRCCOPY);
		EndPaint(hWnd, &ps);
		return 0;
	}
	case WM_TIMER:
		update();
		InvalidateRect(hWnd, NULL, false);
		return 0;
	case WM_DESTROY:
		KillTimer(hWnd, ID_TIMER);
		PostQuitMessage(0);
		return 0;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
} // WndProc