add disable auto camera offset controller

Author: aonkeeper4

Graphics/Atlases/Gameplay/objects/CommunalHelper/disableAutoCameraOffsetController/icon.png

@@ -0,0 +1,12 @@
+local controller = {}
+
+controller.name = "CommunalHelper/DisableAutoCameraOffsetController"
+controller.texture = "objects/CommunalHelper/disableAutoCameraOffsetController/icon"
+controller.placements = {
+    name = "controller",
+    data = {
+        flag = ""
+    }
+}
+
+return controller

Loenn/entities/misc/disable_auto_camera_offset_controller.lua

@@ -1,5 +1,7 @@
 mods.CommunalHelper.name=Communal Helper
 
+# ---------------------- ENTITIES --------------------------
+
 # Dream Refill
 entities.CommunalHelper/DreamRefill.placements.name.dream_refill=Dream Refill
 entities.CommunalHelper/DreamRefill.placements.name.double_dream_refill=Dream Refill (Two Dashes)
@@ -994,6 +996,9 @@ entities.CommunalHelper/DreamTunnelBlocker.placements.name.normal=Dream Tunnel B
 entities.CommunalHelper/DreamTunnelBlocker.attributes.description.blockDreamTunnelDashes=Whether to prevent dream tunneling when dashing into a solid covered by this entity.
 entities.CommunalHelper/DreamTunnelBlocker.attributes.description.blockDreamDashes=Whether to prevent dream dashing when dashing into a dream block covered by this entity.
 
+entities.CommunalHelper/DisableAutoCameraOffsetController.placements.name.controller=Disable Auto Camera Offset Controller
+entities.CommunalHelper/DisableAutoCameraOffsetController.attributes.description.flag=The flag this controller should use to determine when to disable the automatic camera offset that some player states impart.\nLeave empty for this controller to be active always.
+
 # ---------------------- TRIGGERS --------------------------
 
 # [Strawberry Jam] Show Hitbox Trigger
@@ -1115,6 +1120,8 @@ triggers.CommunalHelper/SolarElevatorLevelTrigger.placements.name.trigger=Set So
 triggers.CommunalHelper/SolarElevatorLevelTrigger.attributes.description.elevatorID=The entity ID of the elevator to modify in this room. (integer)
 triggers.CommunalHelper/SolarElevatorLevelTrigger.attributes.description.position=Determines which of the two floors the elevator is sent to.\n- Closest: the one closest to the player when entering the trigger.\n- Bottom: always the bottom floor.\n- Top: always the top floor.
 
+# ---------------------- STYLEGROUNDS --------------------------
+
 # Cloudscape
 style.effects.CommunalHelper/Cloudscape.name=Cloudscape
 style.effects.CommunalHelper/Cloudscape.description.seed=The RNG seed that this cloudscape instance will be generated with.

Loenn/lang/en_gb.lang

@@ -119,6 +119,8 @@ public override void Load()
         AffectSpriteTrigger.Load();
 
         MelvinTargetable.Load();
+        
+        DisableAutoCameraOffsetController.Load();
 
         #region Imports
 
@@ -217,6 +219,8 @@ public override void Unload()
         AffectSpriteTrigger.Unload();
 
         MelvinTargetable.Unload();
+        
+        DisableAutoCameraOffsetController.Unload();
 
         LaserEmitter.Unload();
     }

src/CommunalHelperModule.cs

@@ -0,0 +1,120 @@
+using Celeste.Mod.Helpers;
+using Mono.Cecil.Cil;
+using MonoMod.Cil;
+using MonoMod.RuntimeDetour;
+using System.Reflection;
+
+namespace Celeste.Mod.CommunalHelper.Entities;
+
+[CustomEntity("CommunalHelper/DisableAutoCameraOffsetController")]
+[Tracked]
+public class DisableAutoCameraOffsetController(EntityData data, Vector2 offset) : Entity(data.Position + offset)
+{
+    private readonly string flag = data.Attr("flag");
+
+    private bool IsActive()
+        => string.IsNullOrEmpty(flag) || SceneAs<Level>().Session.GetFlag(flag);
+    
+    #region Hooks
+    
+    private static ILHook ilHook_Player_get_CameraTarget;
+
+    internal static void Load()
+    {
+        ilHook_Player_get_CameraTarget = new ILHook(typeof(Player).GetMethod("get_CameraTarget", BindingFlags.Public | BindingFlags.Instance)!, Player_get_CameraTarget);
+    }
+
+    internal static void Unload()
+    {
+        ilHook_Player_get_CameraTarget.Dispose();
+        ilHook_Player_get_CameraTarget = null;
+    }
+
+    private static void Player_get_CameraTarget(ILContext il)
+    {
+        ILCursor cursor = new(il);
+        
+        // add check for controller being active to the check for StReflectionFall
+        /*
+         * IL_0062: ldarg.0
+         * IL_0063: ldfld class Monocle.StateMachine Celeste.Player::StateMachine
+         * IL_0068: callvirt instance int32 Monocle.StateMachine::get_State()
+         * IL_0032: ldc.i4.s 18
+         * IL_0034: beq.s IL_0062
+         */
+        if (!cursor.TryGotoNextBestFit(MoveType.Before,
+            instr => instr.MatchLdarg(0),
+            instr => instr.MatchLdfld<Player>("StateMachine"),
+            instr => instr.MatchCallvirt<StateMachine>("get_State"),
+            instr => instr.MatchLdcI4(Player.StReflectionFall),
+            instr => instr.MatchBeq(out _)))
+            return;
+        
+        ILCursor cameraOffsetLabelCursor = cursor.Clone();
+        ILLabel setCameraOffset = cameraOffsetLabelCursor.DefineLabel();
+        
+        /*
+         * IL_0036: ldloc.1
+         * IL_0037: ldarg.0
+         * IL_0038: ldfld class Celeste.Level Celeste.Player::level
+         * IL_003d: ldflda valuetype [FNA]Microsoft.Xna.Framework.Vector2 Celeste.Level::CameraOffset
+         */
+        if (!cameraOffsetLabelCursor.TryGotoNextBestFit(MoveType.Before,
+            instr => instr.MatchLdloc(1),
+            instr => instr.MatchLdarg(0),
+            instr => instr.MatchLdfld<Player>("level"),
+            instr => instr.MatchLdflda<Level>("CameraOffset")))
+            return;
+        
+        cameraOffsetLabelCursor.MarkLabel(setCameraOffset);
+
+        cursor.Emit(OpCodes.Ldarg_0);
+        cursor.EmitDelegate(IsControllerActive);
+        cursor.Emit(OpCodes.Brtrue, setCameraOffset);
+        
+        // skip all the state-specific camera offsets if the controller is active
+        /*
+         * IL_0062: ldarg.0
+         * IL_0063: ldfld class Monocle.StateMachine Celeste.Player::StateMachine
+         * IL_0068: callvirt instance int32 Monocle.StateMachine::get_State()
+         * IL_006d: ldc.i4.s 19
+         * IL_006f: bne.un.s IL_00ae
+         */
+        if (!cursor.TryGotoNextBestFit(MoveType.Before,
+            instr => instr.MatchLdarg(0),
+            instr => instr.MatchLdfld<Player>("StateMachine"),
+            instr => instr.MatchCallvirt<StateMachine>("get_State"),
+            instr => instr.MatchLdcI4(Player.StStarFly),
+            instr => instr.MatchBneUn(out _)))
+            return;
+        
+        ILCursor skipStateOffsetLabelCursor = cursor.Clone();
+        ILLabel skipStateOffset = skipStateOffsetLabelCursor.DefineLabel();
+
+        /*
+         * IL_013c: ldarg.0
+         * IL_013d: ldflda valuetype [FNA]Microsoft.Xna.Framework.Vector2 Celeste.Player::CameraAnchorLerp
+         * IL_0142: call instance float32 [FNA]Microsoft.Xna.Framework.Vector2::Length()
+         * IL_0147: ldc.r4 0.0
+         * IL_014c: ble.un IL_024d
+         */
+        if (!skipStateOffsetLabelCursor.TryGotoNextBestFit(MoveType.Before,
+            instr => instr.MatchLdarg(0),
+            instr => instr.MatchLdflda<Player>("CameraAnchorLerp"),
+            instr => instr.MatchCall<Vector2>("Length"),
+            instr => instr.MatchLdcR4(0f),
+            instr => instr.MatchBleUn(out _)))
+            return;
+        
+        skipStateOffsetLabelCursor.MarkLabel(skipStateOffset);
+        
+        cursor.Emit(OpCodes.Ldarg_0);
+        cursor.EmitDelegate(IsControllerActive);
+        cursor.Emit(OpCodes.Brtrue, skipStateOffset);
+    }
+    
+    private static bool IsControllerActive(Player player)
+        => player.Scene?.Tracker?.GetEntity<DisableAutoCameraOffsetController>() is { } controller && controller.IsActive();
+    
+    #endregion
+}