Implement ID24 DemoLoop specification (#2141)

* implement id24 demoloop specification * fixed various assorted issues from draft PR * added further fixes and simplifications to demoloop system * cleaner demoloop internals * implement outro_wipe field functionality * Revert "implement outro_wipe field functionality" This reverts commit 1dba7b2. * added demoloop TODO notice --------- Co-authored-by: Fabian Greffrath <fabian@greffrath.com>
fabiangreffrath · Jan 16, 2025 · f9b9f23 · f9b9f23
1 parent ffa9a39
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diff --git a/README.md b/README.md
@@ -162,7 +162,8 @@ Copyright:
  © 2022-2024 Alaux;  
  © 2022-2024 ceski;  
  © 2023 Andrew Apted;  
- © 2023 liPillON.  
+ © 2023 liPillON;  
+ © 2025 Guilherme Miranda.  
 License: [GPL-2.0+](https://www.gnu.org/licenses/old-licenses/gpl-2.0.html)
 
 Files: `src/i_flickstick.*, src/i_gyro.*`  

diff --git a/src/CMakeLists.txt b/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

diff --git a/src/d_demoloop.c b/src/d_demoloop.c
@@ -0,0 +1,187 @@
+//
+//  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 Specification - User customizable title screen sequence.
+//    Though originally hardcoded on the original Doom engine this allows
+//    for Doom modders to define custom sequences, using any provided custom
+//    graphic-and-music, or DEMO lump.
+//
+
+#include "doomdef.h"
+#include "doomstat.h"
+
+#include "i_printf.h"
+#include "m_array.h"
+#include "m_json.h"
+#include "m_misc.h"
+
+#include "d_demoloop.h"
+
+// Doom
+static demoloop_entry_t demoloop_registered[] = {
+    { "TITLEPIC", "D_INTRO",  170, TYPE_ART,  WIPE_MELT },
+    { "DEMO1",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "CREDIT",   "",         200, TYPE_ART,  WIPE_MELT },
+    { "DEMO2",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "HELP2",    "",         200, TYPE_ART,  WIPE_MELT },
+    { "DEMO3",    "",         0,   TYPE_DEMO, WIPE_MELT },
+};
+
+// Ultimate Doom
+static demoloop_entry_t demoloop_retail[] = {
+    { "TITLEPIC", "D_INTRO",  170, TYPE_ART,  WIPE_MELT },
+    { "DEMO1",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "CREDIT",   "",         200, TYPE_ART,  WIPE_MELT },
+    { "DEMO2",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "CREDIT",   "",         200, TYPE_ART,  WIPE_MELT },
+    { "DEMO3",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "DEMO4",    "",         0,   TYPE_DEMO, WIPE_MELT },
+};
+
+// Doom II & Final Doom
+static demoloop_entry_t demoloop_commercial[] = {
+    { "TITLEPIC", "D_DM2TTL", 385, TYPE_ART,  WIPE_MELT },
+    { "DEMO1",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "CREDIT",   "",         200, TYPE_ART,  WIPE_MELT },
+    { "DEMO2",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "TITLEPIC", "D_DM2TTL", 385, TYPE_ART,  WIPE_MELT },
+    { "DEMO3",    "",         0,   TYPE_DEMO, WIPE_MELT },
+    { "DEMO4",    "",         0,   TYPE_DEMO, WIPE_MELT },
+};
+
+demoloop_t demoloop = NULL;
+int        demoloop_count = 0;
+
+void D_ParseDemoLoopEntry(json_t *entry)
+{
+    const char* primary_buffer   = JS_GetStringValue(entry, "primarylump");
+    const char* secondary_buffer = 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 (primary_buffer == NULL || type <= TYPE_NONE || type > TYPE_DEMO)
+    {
+        primary_buffer = "";
+        type = TYPE_NONE;
+    }
+
+    // Similarly, but this time it isn't game-breaking.
+    // Let it gracefully default to "closest vanilla behavior".
+    if (outro_wipe <= WIPE_NONE || outro_wipe > WIPE_MELT)
+    {
+        outro_wipe = WIPE_MELT;
+    }
+
+    demoloop_entry_t current_entry = {0};
+
+    // Remove pointer reference to in-memory JSON data.
+    M_CopyLumpName(current_entry.primary_lump, primary_buffer);
+    M_CopyLumpName(current_entry.secondary_lump, secondary_buffer);
+    // Providing the time in seconds is much more intuitive for the end users.
+    current_entry.duration   = seconds * TICRATE;
+    current_entry.type       = type;
+    current_entry.outro_wipe = outro_wipe;
+
+    // Should there be a malformed entry, discard it.
+    if (current_entry.type == TYPE_NONE)
+    {
+        return;
+    }
+
+    array_push(demoloop, current_entry);
+}
+
+static 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)
+    {
+        D_ParseDemoLoopEntry(entry);
+    }
+    demoloop_count = array_size(demoloop);
+
+    // No need to keep in memory
+    JS_Close("DEMOLOOP");
+}
+
+static void D_GetDefaultDemoLoop(GameMode_t mode)
+{
+    switch(mode)
+    {
+        case shareware:
+        case registered:
+            demoloop = demoloop_registered;
+            demoloop_count = arrlen(demoloop_registered);
+            break;
+
+        case retail:
+            demoloop = demoloop_retail;
+            demoloop_count = arrlen(demoloop_retail);
+            break;
+
+        case commercial:
+            demoloop = demoloop_commercial;
+            demoloop_count = arrlen(demoloop_commercial);
+            break;
+
+        case indetermined:
+        default:
+            // How did we get here?
+            demoloop = NULL;
+            demoloop_count = 0;
+            break;
+    }
+
+    return;
+}
+
+void D_SetupDemoLoop(void)
+{
+    D_ParseDemoLoop();
+
+    if (demoloop == NULL)
+    {
+        D_GetDefaultDemoLoop(gamemode);
+    }
+}
diff --git a/src/d_demoloop.h b/src/d_demoloop.h
@@ -0,0 +1,61 @@
+//
+//  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 Specification - User customizable title screen sequence.
+//    Though originally hardcoded on the original Doom engine this allows
+//    for Doom modders to define custom sequences, using any provided custom
+//    graphic, music or DEMO lump.
+//
+
+#ifndef _D_DEMOLOOP_
+#define _D_DEMOLOOP_
+
+// Screen graphic or DEMO lump, NONE is used for fault tolerance.
+typedef enum
+{
+    TYPE_NONE = -1,
+    TYPE_ART,
+    TYPE_DEMO,
+} dl_type_t;
+
+// Immediate switch or screen melt, NONE is used for fault tolerance.
+// TODO: reimplement more cleanly at a later, more relevant moment
+typedef enum
+{
+    WIPE_NONE = -1,
+    WIPE_IMMEDIATE,
+    WIPE_MELT,
+} dl_wipe_t;
+
+// Individual demoloop units.
+typedef struct
+{
+    char      primary_lump[9];   // Screen graphic or DEMO lump.
+    char      secondary_lump[9]; // Music lump for screen graphic.
+    int       duration;          // Game tics.
+    dl_type_t type;
+    dl_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;
+
+// Perform both "D_ParseDemoLoop" and "D_GetDefaultDemoLoop".
+void D_SetupDemoLoop(void);
+
+#endif // _D_DEMOLOOP_