Cross-Platform Game Development for C++ Developers, Part IV: ClanLib SDK

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Inside the ClanLib Feature Set

Before digging into the API, take a quick glance at its major features:

• Basic cross-platform runtime (GUI, threading, file I/O, and so forth)
• Template-based C++ signal/slots library (type-safe callbacks/delegates)
• Integrated resource management
• Sound mixer supporting .WAV files, Ogg Vorbis, and anything supported by the MikMod library (MOD, S3M, XM, and so on)
• Document Object Model (DOM) XML parser support
• High-level 2D graphics API supporting OpenGL, DirectX, and SDL as render targets
• Batch rendering engine for best performance when rendering 2D with OpenGL
• 2D collision detection
• 2D sprite animation support
• Highly customizable GUI framework
• Network library with low- to high-level interfaces

The Basic Gaming Model of ClanLib

Now, examine the ClanLib API model from the inside out. I’ve always found that the best tutorial is a fully explained example program. Specifically, you’ll look inside Luke Worth’s boxes, an electronic version of the two-player, paper-and-pencil game (see Figure 2). The boxes game consists of a grid of points between which players alternately draw lines. Whoever encloses a square with the final line, scores one point and gets to play another turn. (If you’re eager to see the API reference first, by all means do so.)

Figure 2. A Boxes Game in Progress with a Score of Blue 8 and Red 3

I purposely kept the main program as short as possible to better highlight the “game loop:”

 1 #include <iostream>
 2 #include <ClanLib/application.h>
 3 #include <ClanLib/core.h>
 4 #include <ClanLib/display.h>
 5 #include <ClanLib/gl.h>
 6 #include <ClanLib/sound.h>
 7 #include <ClanLib/vorbis.h>
 8
 9 const int boardsize = 6, spacing = 50, border = 20;
10 const int numsquares = int(pow(float(boardsize - 1), 2));
11
12 enum coloursquare { off, blue, red };
13 struct cursor {
14    int x, y;
15    bool vert;
16 };
17
18 class Boxes: public CL_ClanApplication {
19    bool ver[boardsize][boardsize - 1];
20    bool hor[boardsize - 1][boardsize];
21    coloursquare squares[boardsize - 1][boardsize - 1];
22    bool redturn;
23    bool fullup;
24    cursor curs;
25
26    void inputHandler(const CL_InputEvent &i);
27    bool findsquares(void);
28    inline int numaroundsquare(int x, int y);
29    void init();
30    void drawBoard();
31    void endOfGame();
32
33 public:
34    virtual int Boxes::main(int, char **);
35 } app;
36
37 using namespace std;

40
41 int Boxes::main(int, char **)
42 {
43    int winsize = spacing * (boardsize - 1) + border * 2;
44    try {
45       Boxes::init();
46       while (!CL_Keyboard::get_keycode(CL_KEY_ESCAPE)) {
47          Boxes::drawBoard();
48          if (fullup) break;
49          CL_System::keep_alive(20);
50    }
51    Boxes::endOfGame();
52
53    CL_SetupVorbis::deinit();
54    CL_SetupSound::deinit();
55    CL_SetupGL::deinit();
56    CL_SetupDisplay::deinit();
57    CL_SetupCore::deinit();
58    }
59    catch (CL_Error err) {
60       std::cout << "Exception caught: "
                   << err.message.c_str()
                   << std::endl;
61    }
62
63 return 0;
64 }