From 120e75d275988c5d723ac827e141d4ea5195e461 Mon Sep 17 00:00:00 2001
From: sphericalice <sphericalice@outlook.com>
Date: Mon, 25 Oct 2021 18:03:14 +0100
Subject: [PATCH] Document the CloseBattlePikeCurtain special

---
 include/constants/metatile_labels.h |  1 +
 include/global.fieldmap.h           |  5 +++++
 src/field_specials.c                | 34 +++++++++++++++++++----------
 3 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/include/constants/metatile_labels.h b/include/constants/metatile_labels.h
index b4ee3eacf..519120082 100644
--- a/include/constants/metatile_labels.h
+++ b/include/constants/metatile_labels.h
@@ -352,6 +352,7 @@
 #define METATILE_InsideShip_IntactDoor_Bottom_Interior 0x297
 
 // gTileset_BattlePike
+#define METATILE_BattlePike_CurtainFrames_Start  0x201
 #define METATILE_BattlePike_Curtain_Stage0_Tile0 0x24A
 #define METATILE_BattlePike_Curtain_Stage0_Tile1 0x251
 #define METATILE_BattlePike_Curtain_Stage0_Tile2 0x252
diff --git a/include/global.fieldmap.h b/include/global.fieldmap.h
index 41b8539ff..a1e752415 100644
--- a/include/global.fieldmap.h
+++ b/include/global.fieldmap.h
@@ -36,6 +36,11 @@ struct Tileset
     /*0x14*/ TilesetCB callback;
 };
 
+// Tilesets do not actually have s strict width.
+// This constant is simply used for the offset between rows of metatiles for
+// large tiles, such as the Battle Pike's curtain tile.
+#define TILESET_WIDTH 8
+
 struct MapLayout
 {
     /*0x00*/ s32 width;
diff --git a/src/field_specials.c b/src/field_specials.c
index ab02f9938..17790532b 100644
--- a/src/field_specials.c
+++ b/src/field_specials.c
@@ -3931,13 +3931,18 @@ static void Task_LoopWingFlapSE(u8 taskId)
 #undef playCount
 #undef delay
 
+#define CURTAIN_HEIGHT 4
+#define CURTAIN_WIDTH 3
+#define tFrameTimer   data
+#define tCurrentFrame data[3]
+
 void CloseBattlePikeCurtain(void)
 {
     u8 taskId = CreateTask(Task_CloseBattlePikeCurtain, 8);
-    gTasks[taskId].data[0] = 4;
-    gTasks[taskId].data[1] = 4;
-    gTasks[taskId].data[2] = 4;
-    gTasks[taskId].data[3] = 0;
+    gTasks[taskId].tFrameTimer[0] = 4;
+    gTasks[taskId].tFrameTimer[1] = 4;
+    gTasks[taskId].tFrameTimer[2] = 4;
+    gTasks[taskId].tCurrentFrame = 0;
 }
 
 static void Task_CloseBattlePikeCurtain(u8 taskId)
@@ -3945,19 +3950,21 @@ static void Task_CloseBattlePikeCurtain(u8 taskId)
     u8 x, y;
     s16 *data = gTasks[taskId].data;
 
-    data[data[3]]--;
-    if (data[data[3]] == 0)
+    tFrameTimer[tCurrentFrame]--;
+    if (tFrameTimer[tCurrentFrame] == 0)
     {
-        for (y = 0; y < 4; y++)
+        for (y = 0; y < CURTAIN_HEIGHT; y++)
         {
-            for (x = 0; x < 3; x++)
+            for (x = 0; x < CURTAIN_WIDTH; x++)
             {
-                MapGridSetMetatileIdAt(gSaveBlock1Ptr->pos.x + x + 6, gSaveBlock1Ptr->pos.y + y + 4, x + 513 + y * 8 + data[3] * 32);
+                MapGridSetMetatileIdAt(gSaveBlock1Ptr->pos.x + x + MAP_OFFSET - 1,
+                                       gSaveBlock1Ptr->pos.y + y + MAP_OFFSET - 3,
+                                       (x + METATILE_BattlePike_CurtainFrames_Start) + (y * TILESET_WIDTH) + (tCurrentFrame * CURTAIN_HEIGHT * TILESET_WIDTH));
             }
         }
         DrawWholeMapView();
-        data[3]++;
-        if (data[3] == 3)
+        tCurrentFrame++;
+        if (tCurrentFrame == 3)
         {
             DestroyTask(taskId);
             EnableBothScriptContexts();
@@ -3965,6 +3972,11 @@ static void Task_CloseBattlePikeCurtain(u8 taskId)
     }
 }
 
+#undef CURTAIN_HEIGHT
+#undef CURTAIN_WIDTH
+#undef tFrameTimer
+#undef tCurrentFrame
+
 void GetBattlePyramidHint(void)
 {
     gSpecialVar_Result = gSpecialVar_0x8004 / 7;