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  <title>Architecture — Free Eggbert Documentation</title>
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        <h1>Architecture Overview</h1>
        <p>
          Free Eggbert's architecture closely mirrors the original Win32/DirectX 3 game structure,
          reconstructed from binary analysis. The codebase is structured as a set of cooperating
          C++ classes managed through a classic Win32 application model.
        </p>

        <h2 id="layered-architecture">Layered Architecture</h2>
        <pre><code>┌──────────────────────────────────────┐
│       Game Logic (C++20)             │
│  blupi.cpp / CDecor / CEvent / …     │
├──────────────────────────────────────┤
│  Free API  (Win32 → cross-platform)  │
│  Free Direct (DirectX → SDL3)        │
├──────────────────────────────────────┤
│  SDL3 / SDL_image / SDL_mixer        │
└──────────────────────────────────────┘</code></pre>
        <p>
          Game code only includes WinAPI-like and DirectX-like compatibility headers
          (<code>windows.h</code>, <code>ddraw.h</code>, <code>dsound.h</code>, etc.).
          SDL is never included directly by game source files.
        </p>

        <h2 id="main-entry">Main Entry Point</h2>
        <p>
          <strong>Source file:</strong> <code>src/blupi.cpp</code><br>
          <strong>Entry function:</strong> <code>WinMain()</code> (Win32-style)
        </p>
        <p>
          <code>blupi.cpp</code> contains the application bootstrap, window creation,
          message loop, and top-level object instantiation.
        </p>

        <h3 id="init-sequence">Initialization Sequence</h3>
        <ol>
          <li>Create the application window</li>
          <li>Instantiate <strong>CPixmap</strong> — DirectDraw surface manager</li>
          <li>Call <code>CPixmap::Create()</code> — initialize display surfaces</li>
          <li>Call <code>CPixmap::CacheAll(TRUE, …)</code> — load all image assets</li>
          <li>Instantiate <strong>CSound</strong> — audio system</li>
          <li>Instantiate <strong>CNetwork</strong> — DirectPlay (fails silently in most configs)</li>
          <li>Instantiate <strong>CDecor</strong> — game world and logic engine</li>
          <li>Instantiate <strong>CEvent</strong> — input handler and game phase dispatcher</li>
          <li>Start multimedia timer for game tick updates</li>
          <li>Enter the main message loop</li>
        </ol>

        <div class="callout warning">
          <span class="callout-icon">⚠️</span>
          <div class="callout-body">
            <div class="callout-title">Known Initialization Issue</div>
            The decompiled code calls <code>CPixmap::Create()</code> twice during startup —
            once directly, and once inside <code>CPixmap::CacheAll(TRUE, …)</code>.
            This is a suspected decompilation artifact. Real DirectDraw may reject the
            second initialization. See <a href="development/known-issues.html">Known Issues</a>.
          </div>
        </div>

        <h2 id="main-loop">Main Game Loop</h2>
        <p>The application uses a classic Win32 message loop with a multimedia timer:</p>
        <pre><code><span class="cmt">// WinMain (blupi.cpp) — simplified</span>
g_updateTimer = timeSetEvent(g_timerInterval, g_timerInterval / 4,
                             TimerStep, NULL, TIME_PERIODIC);

<span class="kw">while</span> (TRUE) {
    <span class="kw">if</span> (PeekMessage(&amp;msg, NULL, 0, 0, PM_NOREMOVE)) {
        <span class="kw">if</span> (!GetMessage(&amp;msg, NULL, 0, 0))
            <span class="kw">return</span> msg.wParam;
        TranslateMessage(&amp;msg);
        DispatchMessage(&amp;msg);
    } <span class="kw">else</span> {
        <span class="kw">if</span> (!g_bActive) WaitMessage();
    }
}</code></pre>

        <p>
          The timer callback posts update messages. The window procedure handles
          <code>WM_UPDATE</code> by calling:
        </p>
        <pre><code>UpdateFrame();
SetDecor();
g_pPixmap-&gt;Display();</code></pre>

        <h2 id="core-classes">Core Classes</h2>
        <div class="table-wrap">
          <table>
            <thead><tr><th>Class</th><th>Header</th><th>Source(s)</th><th>Responsibility</th></tr></thead>
            <tbody>
              <tr>
                <td><a href="modules/cdecor.html"><code>CDecor</code></a></td>
                <td><code>include/decor.hpp</code></td>
                <td><code>src/decor*.cpp</code></td>
                <td>Central game engine — world state, all game logic</td>
              </tr>
              <tr>
                <td><a href="modules/cevent.html"><code>CEvent</code></a></td>
                <td><code>include/event.hpp</code></td>
                <td><code>src/event.cpp</code></td>
                <td>Input handling, game phase dispatch, keyboard/mouse</td>
              </tr>
              <tr>
                <td><a href="modules/cpixmap.html"><code>CPixmap</code></a></td>
                <td><code>include/pixmap.hpp</code></td>
                <td><code>src/pixmap.cpp</code></td>
                <td>DirectDraw surface manager, sprite blitting</td>
              </tr>
              <tr>
                <td><a href="modules/csound.html"><code>CSound</code></a></td>
                <td><code>include/sound.hpp</code></td>
                <td><code>src/sound.cpp</code>, <code>src/soundbass.cpp</code></td>
                <td>Audio playback — DirectSound or BASS backend</td>
              </tr>
              <tr>
                <td><a href="modules/cnetwork.html"><code>CNetwork</code></a></td>
                <td><code>include/network.hpp</code></td>
                <td><code>src/network.cpp</code></td>
                <td>DirectPlay session management, multiplayer</td>
              </tr>
              <tr>
                <td><code>CButton</code></td>
                <td><code>include/button.hpp</code></td>
                <td><code>src/button.cpp</code></td>
                <td>UI button rendering and hit-testing</td>
              </tr>
              <tr>
                <td><code>CJauge</code></td>
                <td><code>include/jauge.hpp</code></td>
                <td><code>src/jauge.cpp</code></td>
                <td>Progress/gauge bar rendering</td>
              </tr>
              <tr>
                <td><code>CMenu</code></td>
                <td><code>include/menu.hpp</code></td>
                <td><code>src/menu.cpp</code></td>
                <td>Menu rendering and navigation</td>
              </tr>
            </tbody>
          </table>
        </div>

        <h2 id="cdecor-decomposition">CDecor Source File Decomposition</h2>
        <p>
          <code>CDecor</code> is the most important class. Its implementation is split
          across 8 source files by responsibility:
        </p>
        <div class="table-wrap">
          <table>
            <thead><tr><th>File</th><th>Responsibility</th></tr></thead>
            <tbody>
              <tr><td><code>src/decor.cpp</code></td><td>Initialization, rendering, main step loop, region/music</td></tr>
              <tr><td><code>src/decblupi.cpp</code></td><td>Player movement, jumping, vehicle logic, physics</td></tr>
              <tr><td><code>src/decblock.cpp</code></td><td>Block/crate interaction, push/pull, door logic</td></tr>
              <tr><td><code>src/decmove.cpp</code></td><td>Moving object (enemy/bomb/effect) step logic</td></tr>
              <tr><td><code>src/decnet.cpp</code></td><td>Network game synchronization and event dispatch</td></tr>
              <tr><td><code>src/decdesign.cpp</code></td><td>Level editor — place/remove tiles and objects</td></tr>
              <tr><td><code>src/decio.cpp</code></td><td>Save/load game state to .blp files</td></tr>
              <tr><td><code>src/dectables.cpp</code></td><td>Static lookup tables for decor</td></tr>
            </tbody>
          </table>
        </div>

        <h2 id="world-grid">World Grid System</h2>
        <p>
          The game world is a <strong>100×100 grid</strong> of cells.
          Each cell stores a sprite index into the background/decor spritesheet.
        </p>
        <ul>
          <li>Grid dimensions: <code>MAXCELX</code> × <code>MAXCELY</code> = 100×100</li>
          <li>Object sprites: 64×64 px (<code>DIMOBJX</code>, <code>DIMOBJY</code>)</li>
          <li>Player sprites: 60×60 px (<code>DIMBLUPIX</code>, <code>DIMBLUPIY</code>)</li>
          <li>Explosion sprites: 128×128 px (<code>DIMEXPLOX</code>, <code>DIMEXPLOY</code>)</li>
        </ul>

        <h2 id="render-channels">Render Channel System</h2>
        <p>
          <code>CPixmap</code> manages <strong>15 independent DirectDraw surfaces</strong>,
          each identified by a channel constant. Layers are composited in order to build the
          final frame:
        </p>
        <div class="table-wrap">
          <table>
            <thead><tr><th>Channel</th><th>Value</th><th>Content</th></tr></thead>
            <tbody>
              <tr><td><code>CHBACK</code></td><td>0</td><td>Background terrain</td></tr>
              <tr><td><code>CHOBJECT</code></td><td>1</td><td>Foreground objects and pickups</td></tr>
              <tr><td><code>CHBLUPI</code></td><td>2</td><td>Player character</td></tr>
              <tr><td><code>CHDECOR</code></td><td>3</td><td>Decorative overlays</td></tr>
              <tr><td><code>CHBUTTON</code></td><td>4</td><td>UI buttons</td></tr>
              <tr><td><code>CHJAUGE</code></td><td>5</td><td>Gauge/progress bars</td></tr>
              <tr><td><code>CHTEXT</code></td><td>6</td><td>Normal text characters</td></tr>
              <tr><td><code>CHLITTLE</code></td><td>7</td><td>Small text characters</td></tr>
              <tr><td><code>CHMAP</code></td><td>8</td><td>Minimap</td></tr>
              <tr><td><code>CHEXPLO</code></td><td>9</td><td>Explosion sprites</td></tr>
              <tr><td><code>CHELEMENT</code></td><td>10</td><td>Particle/element effects</td></tr>
              <tr><td><code>CHBLUPI1–3</code></td><td>11–13</td><td>Player character variants (multiplayer)</td></tr>
              <tr><td><code>CHTEMP</code></td><td>14</td><td>Temporary scratch surface</td></tr>
            </tbody>
          </table>
        </div>
        <p>See <a href="reference/image-channels.html">Image Channels</a> for the full reference.</p>

        <h2 id="game-phases">Game Phase System</h2>
        <p>
          Game state is controlled by <strong>game phases</strong>, dispatched as Windows messages
          (<code>WM_USER + N</code>) and handled by <code>CEvent</code>. Examples:
        </p>
        <ul>
          <li><code>WM_PHASE_INIT</code> — startup initialization</li>
          <li><code>WM_PHASE_PLAY</code> — normal gameplay</li>
          <li><code>WM_PHASE_WIN</code> / <code>WM_PHASE_LOST</code> — end of level</li>
          <li><code>WM_PHASE_SETUP</code> — settings screen</li>
          <li><code>WM_PHASE_BUILD</code> — level editor</li>
          <li><code>WM_PHASE_SERVICE</code> / <code>SESSION</code> / <code>MULTI</code> — multiplayer lobby</li>
        </ul>
        <p>See <a href="reference/game-phases.html">Game Phases Reference</a> for all 60+ phases.</p>

        <h2 id="object-system">Moving Object System</h2>
        <p>
          Up to <strong>200 moving objects</strong> (<code>MAXMOVEOBJECT</code>) can be active
          simultaneously. They are tracked in a fixed-size <code>MoveObject[200]</code> array
          within <code>CDecor</code>. Each object has a type (<code>TYPE_*</code>),
          position, animation state, and motion trajectory.
        </p>
        <p>
          Object types include enemies (fish, bird, wasp), vehicles, bombs,
          collectibles, and visual effects. See <a href="reference/object-types.html">Object Types</a>.
        </p>

        <h2 id="player-state">Player State</h2>
        <p>
          Unlike the Planet Blupi engine which uses a <code>Blupi[100]</code> array,
          Free Eggbert stores the player state as individual member fields directly in
          <code>CDecor</code> (<code>m_blupiPos</code>, <code>m_blupiAction</code>,
          <code>m_blupiDir</code>, etc.).
        </p>
        <p>In multiplayer, up to 4 players are tracked via network packets.</p>

        <h2 id="audio-arch">Audio Architecture</h2>
        <p>
          Audio is managed by <code>CSound</code> with two selectable backends
          controlled by the <code>_BASS</code> compile flag:
        </p>
        <ul>
          <li><strong>Default (<code>_BASS=FALSE</code>)</strong>: <code>src/sound.cpp</code> — DirectSound/MCI path</li>
          <li><strong>BASS library (<code>_BASS=TRUE</code>)</strong>: <code>src/soundbass.cpp</code> — BASS + BASSMIDI</li>
        </ul>
        <p>See <a href="audio.html">Audio System</a> for full documentation.</p>

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