Fix GMS2 instance depth by assigning from room layers instead of OBJT definitions

Fixes the duplicated Kris in the room_krishallway, and probably other depth issues

Author: MrPowerGamerBR

src/runner.c

@@ -567,15 +567,8 @@ void Runner_draw(Runner* runner) {
                             runner->renderer->vtable->drawSprite(runner->renderer, tpagIndex, d->layer->xOffset, d->layer->yOffset, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0xFFFFFF, 1.0);
                         }
             } else if(d->layer->type == RoomLayerType_Instances) {
-                RoomLayerInstancesData *data = d->layer->instancesData;
-                // TODO: This isn't the right way to do this
-                repeat(data->instanceCount, i) {
-                    Instance* inst = hmget(runner->instancesToId, data->instanceIds[i]);
-                    if (inst == nullptr)
-                        continue;
-                    if(inst->depth == 0)
-                        inst->depth = d->layer->depth;
-                }
+                // Instance depth is assigned from layers during room init (initRoom).
+                // Nothing to do here - instances are drawn from the DRAWABLE_INSTANCE path.
             }
         }
     }
@@ -761,6 +754,22 @@ static void initRoom(Runner* runner, int32_t roomIndex) {
         inst->imageAngle = (float) roomObj->rotation;
     }
 
+    // In GMS2, instances get their depth from their room layer, not the object definition.
+    // This must happen before firing Create events so scripts like scr_depth() read the layer depth.
+    if (runner->isGMS2) {
+        repeat(room->layerCount, li) {
+            RoomLayer* layer = &room->layers[li];
+            if (layer->type != RoomLayerType_Instances || layer->instancesData == nullptr) continue;
+            RoomLayerInstancesData* layerData = layer->instancesData;
+            repeat(layerData->instanceCount, ii) {
+                Instance* inst = hmget(runner->instancesToId, layerData->instanceIds[ii]);
+                if (inst != nullptr) {
+                    inst->depth = layer->depth;
+                }
+            }
+        }
+    }
+
     // Pass 2: Fire events for newly created instances (in room definition order)
     repeat(room->gameObjectCount, i) {
         RoomGameObject* roomObj = &room->gameObjects[i];

src/runner.h

@@ -107,6 +107,8 @@ typedef struct Runner {
     struct { char* key; int value; }* disabledObjects; // stb_ds string hashmap, nullptr = no filtering
     struct { int key; Instance* value; }* instancesToId;
     bool isGMS2;
+    bool forceDrawDepth;
+    int32_t forcedDepth;
 } Runner;
 
 const char* Runner_getEventName(int32_t eventType, int32_t eventSubtype);

src/vm_builtins.c

@@ -4417,6 +4417,33 @@ static RValue builtinTileLayerShift(MAYBE_UNUSED VMContext* ctx, RValue* args, M
     return RValue_makeUndefined();
 }
 
+// ===[ Layer Functions ]===
+
+static RValue builtinLayerForceDrawDepth(VMContext* ctx, RValue* args, MAYBE_UNUSED int32_t argCount) {
+    Runner* runner = (Runner*) ctx->runner;
+    runner->forceDrawDepth = RValue_toBool(args[0]);
+    runner->forcedDepth = RValue_toInt32(args[1]);
+    return RValue_makeUndefined();
+}
+
+static RValue builtinLayerIsDrawDepthForced(VMContext* ctx, MAYBE_UNUSED RValue* args, MAYBE_UNUSED int32_t argCount) {
+    Runner* runner = (Runner*) ctx->runner;
+    return RValue_makeBool(runner->forceDrawDepth);
+}
+
+static RValue builtinLayerGetForcedDepth(VMContext* ctx, MAYBE_UNUSED RValue* args, MAYBE_UNUSED int32_t argCount) {
+    Runner* runner = (Runner*) ctx->runner;
+    return RValue_makeReal((GMLReal) runner->forcedDepth);
+}
+
+// ===[ Array Functions ]===
+
+// @@NewGMLArray@@ - GMS2 internal function to create a new empty array.
+// In our VM, arrays are created implicitly on first write, so this is a no-op.
+static RValue builtinNewGMLArray(MAYBE_UNUSED VMContext* ctx, MAYBE_UNUSED RValue* args, MAYBE_UNUSED int32_t argCount) {
+    return RValue_makeUndefined();
+}
+
 // ===[ PATH FUNCTIONS ]===
 
 // path_start(path, speed, endaction, absolute) - HTML5: Assign_Path (yyInstance.js:2695-2743)
@@ -5080,6 +5107,14 @@ void VMBuiltins_registerAll(bool isGMS2) {
     registerBuiltin("tile_layer_show", builtinTileLayerShow);
     registerBuiltin("tile_layer_shift", builtinTileLayerShift);
 
+    // Layer
+    registerBuiltin("layer_force_draw_depth", builtinLayerForceDrawDepth);
+    registerBuiltin("layer_is_draw_depth_forced", builtinLayerIsDrawDepthForced);
+    registerBuiltin("layer_get_forced_depth", builtinLayerGetForcedDepth);
+
+    // GMS2 internal
+    registerBuiltin("@@NewGMLArray@@", builtinNewGMLArray);
+
     // Path
     registerBuiltin("path_start", builtinPathStart);
     registerBuiltin("path_end", builtinPathEnd);