implement id24 demoloop specification

src/CMakeLists.txt

@@ -3,6 +3,7 @@ include(WoofSettings)
 set(WOOF_SOURCES
     am_map.c               am_map.h
     d_deh.c                d_deh.h
+    d_demoloop.c           d_demoloop.h
                            d_englsh.h
                            d_event.h
                            d_french.h

src/d_demoloop.c

@@ -0,0 +1,306 @@
+//
+//  Copyright (C) 2025 Guilherme Miranda
+//
+//  This program is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU General Public License
+//  as published by the Free Software Foundation; either version 2
+//  of the License, or (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  DESCRIPTION:
+//    ID24 DemoLoop
+
+#include "doomdef.h"
+#include "doomstat.h"
+
+#include "i_printf.h"
+#include "m_array.h"
+#include "m_json.h"
+#include "w_wad.h"
+
+#include "d_demoloop.h"
+
+// DEMO1 lump playback.
+static const demoloop_entry_t dl_demo1 = {
+    "DEMO1",
+    "",
+    0,
+    TYPE_DEMO_LUMP,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// DEMO2 lump playback.
+static const demoloop_entry_t dl_demo2 = {
+    "DEMO2",
+    "",
+    0,
+    TYPE_DEMO_LUMP,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// DEMO3 lump playback.
+static const demoloop_entry_t dl_demo3 = {
+    "DEMO3",
+    "",
+    0,
+    TYPE_DEMO_LUMP,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// DEMO4 lump, only present in Ultimate Doom.
+// The DEMO4 entry crashed in the original Final Doom EXE's loop.
+static const demoloop_entry_t dl_demo4 = {
+    "DEMO4",
+    "",
+    0,
+    TYPE_DEMO_LUMP,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// Oddly, Doom's TITLEPIC lasts for a brifer period than Doom II.
+// About ~4.857 seconds, as opposed to Doom II's exact 11 seconds.
+static const demoloop_entry_t dl_doom1_titlepic = {
+    "TITLEPIC",
+    "D_INTRO",
+    170,
+    TYPE_ART_SCREEN,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// HELP2 titlescreen lasts for about ~5.714 seconds.
+// Used only in Registered mode.
+static const demoloop_entry_t dl_help2 = {
+    "HELP2",
+    "",
+    200,
+    TYPE_ART_SCREEN,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// Plain Doom II, Commercial mode, TITLEPIC lasts for exactly 11.0 seconds.
+static const demoloop_entry_t dl_doom2_titlepic = {
+    "TITLEPIC",
+    "D_DM2TTL",
+    385,
+    TYPE_ART_SCREEN,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// CREDIT titlescreen lasts for about ~5.714 seconds.
+// Used in Retail and Commercial mode.
+static const demoloop_entry_t dl_credit = {
+    "CREDIT",
+    "",
+    200,
+    TYPE_ART_SCREEN,
+    OUTRO_WIPE_SCREEM_MELT,
+};
+
+// Used to check for fault tolerance
+static const demoloop_entry_t dl_none = {
+    "",
+    "",
+    0,
+    TYPE_NONE,
+    OUTRO_WIPE_NONE,
+};
+
+// Doom
+demoloop_entry_t demoloop_registered[6] = {
+    dl_doom1_titlepic,
+    dl_demo1,
+    dl_credit,
+    dl_demo2,
+    dl_help2,
+    dl_demo3,
+};
+
+// Ultiamte Doom
+demoloop_entry_t demoloop_retail[7] = {
+    dl_doom1_titlepic,
+    dl_demo1,
+    dl_credit,
+    dl_demo2,
+    dl_credit,
+    dl_demo3,
+    dl_demo4,
+};
+
+// Doom II & fixed Final Doom
+demoloop_entry_t demoloop_commercial[6] = {
+    dl_doom2_titlepic,
+    dl_demo1,
+    dl_credit,
+    dl_demo2,
+    dl_doom2_titlepic,
+    dl_demo3,
+};
+
+// TNT: Evilution & The Plutonia Experiement
+demoloop_entry_t demoloop_final[7] = {
+    dl_doom2_titlepic,
+    dl_demo1,
+    dl_credit,
+    dl_demo2,
+    dl_doom2_titlepic,
+    dl_demo3,
+    dl_demo4,
+};
+
+// For local parsing purposes only.
+static demoloop_entry_t current_entry;
+
+demoloop_t demoloop;
+int        demoloop_count = 0;
+int        demoloop_current = -1;
+
+
+// TODO: actually finish this and make it work
+demoloop_entry_t D_ParseDemoLoopEntry(json_t *entry)
+{
+    const char* primary_lump   = JS_GetStringValue(entry, "primarylump");
+    const char* secondary_lump = JS_GetStringValue(entry, "secondarylump");
+    double      seconds        = JS_GetNumberValue(entry, "duration");
+    int         type           = JS_GetIntegerValue(entry, "type");
+    int         outro_wipe     = JS_GetIntegerValue(entry, "outro_wipe");
+
+    // We don't want a malformed entry to creep in, and break the titlescreen.
+    // If one such entry does exist, skip it.
+    // TODO: modify later to check locally for lump type.
+    if (type <= TYPE_NONE || type > TYPE_DEMO_LUMP)
+    {
+        return dl_none;
+    }
+
+    // Similarly, but this time it isn't game-breaking.
+    // Let it gracefully default to "closest vanilla behavior".
+    if (outro_wipe <= OUTRO_WIPE_NONE || outro_wipe > OUTRO_WIPE_SCREEM_MELT)
+    {
+        outro_wipe = OUTRO_WIPE_SCREEM_MELT;
+    }
+
+    // Providing the time in seconds is much more intuitive for the end users.
+    int duration = seconds * TICRATE;
+
+    demoloop_entry_t demoloop_entry = {
+        primary_lump,
+        secondary_lump,
+        duration,
+        type,
+        outro_wipe,
+    };
+
+    return demoloop_entry;
+}
+
+void D_ParseDemoLoop(void)
+{
+    // Does the JSON lump even exist?
+    json_t *json = JS_Open("DEMOLOOP", "demoloop", (version_t){1, 0, 0});
+    if (json == NULL)
+    {
+        return;
+    }
+
+    // Does lump actually have any data?
+    json_t *data = JS_GetObject(json, "data");
+    if (JS_IsNull(data) || !JS_IsObject(data))
+    {
+        I_Printf(VB_WARNING, "DEMOLOOP: data object not defined");
+        JS_Close("DEMOLOOP");
+        return;
+    }
+
+    // Does is it even have the definitions we are looking for?
+    json_t *entry_list = JS_GetObject(data, "entries");
+    if (JS_IsNull(entry_list) || !JS_IsArray(entry_list))
+    {
+        I_Printf(VB_WARNING, "DEMOLOOP: no entries defined");
+        JS_Close("DEMOLOOP");
+        return;
+    }
+
+    // If so, now parse them.
+    json_t *entry;
+
+    JS_ArrayForEach(entry, entry_list)
+    {
+        current_entry = D_ParseDemoLoopEntry(entry);
+
+        // Should there be a malformed entry, discard it.
+        if (current_entry.type == TYPE_NONE)
+        {
+            continue;
+        }
+
+        array_push(demoloop, current_entry);
+        demoloop_count++;
+    }
+
+    return;
+}
+
+void D_GetDefaultDemoLoop(GameMission_t mission, GameMode_t mode)
+{
+    switch(mission) {
+        case doom:
+            // The versions of Doom that have HELP2, instead.
+            if (mode == registered || mode == shareware) {
+                demoloop = demoloop_registered;
+                demoloop_count = 6;
+                break;
+            }
+        case pack_chex3v:
+            // Check for chex3d2.wad, "Chex Quest 3: Modding Edition".
+            if (mode == commercial) {
+                demoloop = demoloop_commercial;
+                demoloop_count = 6;
+                break;
+            }
+        case pack_rekkr:
+        case pack_chex:
+            // Plain Ultimate Doom
+            demoloop = demoloop_retail;
+            demoloop_count = 7;
+            break;
+
+        case doom2:
+        case pack_hacx:
+            // Plain Doom II
+            demoloop = demoloop_commercial;
+            demoloop_count = 6;
+            break;
+
+        case pack_tnt:
+        case pack_plut:
+            // Plain Final Doom
+            demoloop = demoloop_final;
+            demoloop_count = 7;
+            break;
+
+        case none:
+        default:
+            // How did we get here?
+            demoloop = NULL;
+            demoloop_count = 0;
+            break;
+    }
+
+    return;
+}
+
+void D_SetupDemoLoop(void) {
+    if (W_CheckNumForName("DEMOLOOP") >= 0)
+    {
+        D_ParseDemoLoop();
+    }
+
+    if (demoloop == NULL)
+    {
+        D_GetDefaultDemoLoop(gamemission, gamemode);
+    }
+}

src/d_demoloop.h

@@ -0,0 +1,59 @@
+//
+//  Copyright (C) 2025 Guilherme Miranda
+//
+//  This program is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU General Public License
+//  as published by the Free Software Foundation; either version 2
+//  of the License, or (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  DESCRIPTION:
+//    ID24 DemoLoop
+
+#include "doomdef.h"
+
+// Screen graphic or DEMO lump, NONE is used for fault tolerance.
+typedef enum
+{
+    TYPE_NONE = -1,
+    TYPE_ART_SCREEN,
+    TYPE_DEMO_LUMP,
+} dl_type_t;
+
+// Immediate switch or screen melt, NONE is used for fault tolerance.
+typedef enum
+{
+    OUTRO_WIPE_NONE = -1,
+    OUTRO_WIPE_IMMEDIATE,
+    OUTRO_WIPE_SCREEM_MELT,
+} dl_outro_wipe_t;
+
+// Individual demoloop units.
+typedef struct
+{
+    const char*     primary_lump;   // Screen graphic or DEMO lump.
+    const char*     secondary_lump; // Music lump for screen graphic.
+    int             duration;       // Game tics.
+    dl_type_t       type;
+    dl_outro_wipe_t outro_wipe;
+} demoloop_entry_t;
+
+typedef demoloop_entry_t* demoloop_t;
+
+// Actual DemoLoop data structure.
+extern demoloop_t demoloop;
+// Formerly 7 for Ultimate Doom & Final Doom, 6 otherwise.
+extern int        demoloop_count;
+// Formerly "demosequence".
+extern int        demoloop_current;
+
+// Parse the DEMOLOOP, returning NULL to "demoloop" should any errors occur.
+void D_ParseDemoLoop(void);
+// If "demoloop" is NULL, check for defaults using mission and mode.
+void D_GetDefaultDemoLoop(GameMission_t mission, GameMode_t mode);
+// Perform both "D_ParseDemoLoop" and "D_GetDefaultDemoLoop".
+void D_SetupDemoLoop(void);