Turbo Vision Snake Example

README.md

This is an extremely basic Snake example using Turbo Vision. It doesn't even implement the game logic; it just shows a snake emoji that can be moved with the arrow keys or the mouse.

To build on Unix:

1. Make sure the following are installed:
   • A C++ compiler (e.g. GCC or Clang).
   • A build generator (e.g. Make or Ninja).
   • git, CMake and Ncurses.
2. Run:

   git clone https://github.com/magiblot/tvision && (
       cd tvision &&
       cmake . -B ./build -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX=$HOME/.local &&
       cmake --build ./build -- -j$(nproc) &&
       cmake --install ./build
   )

3. Place snake.cc and CMakeLists.txt in a clean directory. Then run:

   cmake . -B ./build -DCMAKE_BUILD_TYPE=RelWithDebInfo &&
   cmake --build ./build -- -j$(nproc)

4. Run ./build/snake.

CMakeLists.txt

cmake_minimum_required(VERSION 3.5)

project(snake)

add_executable(snake snake.cc)

find_package(tvision CONFIG)
target_link_libraries(snake tvision::tvision)

snake.cc

#define Uses_TKeys
#define Uses_TApplication
#define Uses_TDeskTop
#define Uses_TEvent
#define Uses_TMenuBar
#define Uses_TSubMenu
#define Uses_TMenuItem
#define Uses_TStatusLine
#define Uses_TStatusItem
#define Uses_TStatusDef
#include <tvision/tv.h>

class SnakeApp : public TApplication
{

public:

    SnakeApp();

    static TMenuBar *initMenuBar(TRect);
    static TStatusLine *initStatusLine(TRect);

};

class SnakeView : public TView
{

    TPoint pos;

public:

    SnakeView(const TRect &bounds);

    void handleEvent(TEvent &ev) override;
    void draw() override;

};

SnakeApp::SnakeApp() :
    TProgInit( &SnakeApp::initStatusLine,
               &SnakeApp::initMenuBar,
               &TApplication::initDeskTop )
{
    // Create an instance of our Snake game and place it on the desktop.
    TRect r = deskTop->getExtent().grow(-2, -1);
    auto *snakeView = new SnakeView(r);
    deskTop->insert(snakeView);
}

TMenuBar *SnakeApp::initMenuBar(TRect r)
{
    r.b.y = r.a.y + 1;
    return new TMenuBar(r,
        *new TSubMenu("~F~ile", kbAltF) +
            *new TMenuItem("E~x~it", cmQuit, kbNoKey, hcNoContext, "Alt-X")
    );
}

TStatusLine *SnakeApp::initStatusLine(TRect r)
{
    r.a.y = r.b.y - 1;
    return new TStatusLine(r,
        *new TStatusDef(0, 0xFFFF) +
            *new TStatusItem("~Alt-X~ Exit", kbAltX, cmQuit) +
            *new TStatusItem(0, kbF10, cmMenu)
            );
}

SnakeView::SnakeView(const TRect &bounds) :
    TView(bounds)
{
    growMode = gfGrowHiX | gfGrowHiY; // So that it gets resized along the desktop.
    options |= ofSelectable; // Otherwise it won't react to key/mouse events.
    eventMask |= evKeyDown | evMouseDown | evMouseMove;
    pos.x = (bounds.b.x - bounds.a.x)/2; // Display the snake at the center of the screen.
    pos.y = (bounds.b.y - bounds.a.y)/2;
}

void SnakeView::handleEvent(TEvent &event)
{
    TView::handleEvent(event);
    bool handled = true;
    switch (event.what)
    {
        case evKeyDown:
        {
            switch (event.keyDown.keyCode)
            {   // Arrow keys move the snake by one position.
                case kbUp:
                    pos.y = max(pos.y - 1, 0);
                    break;
                case kbDown:
                    pos.y = min(pos.y + 1, size.y - 1);
                    break;
                case kbLeft:
                    pos.x = max(pos.x - 2, 0); // The snake emoji is two columns wide,
                    break;                     // so it moves by two horizontal positions.
                case kbRight:
                    pos.x = min(pos.x + 2, size.x - 2);
                    break;
                default:
                    handled = false;
                    break;
            }
            break;
        }
        // Mouse press and drag also move the snake:
        case evMouseDown:
        case evMouseMove:
            pos = makeLocal(event.mouse.where);
            break;
        default:
            handled = false;
            break;
    }
    if (handled)
    {
        drawView();
        clearEvent(event);
    }
}

void SnakeView::draw()
{
    if (0 <= size.x && 0 <= size.y)
    {
        TDrawBuffer b;

        TColorAttr cSnake {0xcc33ff, 0x33cc33}; // {foreground, background} in RGB.
        TColorAttr cBgrnd {0xffcc00, 0xccff33};

        for (int x = 0; x < size.x; ++x)
            b.moveStr(x, "░", cBgrnd);

        writeLine(0, 0, size.x, size.y, b); // Draw the background.

        b.moveStr(0, "🐍", cSnake);
        writeLine(pos.x, pos.y, 2, 1, b); // Draw the snake.
    }
}

int main()
{
    SnakeApp app;
    app.run();
    app.shutDown();
}