From e30907d09f32c3b3c749e995939c77dba56c40b4 Mon Sep 17 00:00:00 2001
From: Untold Engine <harold.serrano@untoldengine.com>
Date: Wed, 7 Oct 2026 18:37:02 -0700
Subject: [PATCH] [Bugfix] Fix bounding box offset for multi-node models
 selected via scenegraph

Selecting a dragged-in multi-node asset (e.g. goalpost) in the scenegraph
highlighted a bounding box offset from the visible mesh. The highlight
accumulation composed each child's bbox contribution using the parent's
own local transform instead of the child's, so a mesh living on a child
entity with its own position offset from its container root rendered its
box in the wrong place.
---
 .../Editor/Project/SelectionManager.swift     | 14 +++++-
 .../SelectionSeveralTests.swift               | 44 +++++++++++++++++++
 2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/Sources/UntoldEditor/Editor/Project/SelectionManager.swift b/Sources/UntoldEditor/Editor/Project/SelectionManager.swift
index 3184fff..464da65 100644
--- a/Sources/UntoldEditor/Editor/Project/SelectionManager.swift
+++ b/Sources/UntoldEditor/Editor/Project/SelectionManager.swift
@@ -553,8 +553,13 @@ class SelectionManager: ObservableObject {
             foundBounds = true
         }
 
-        let childLocalToRoot = simd_mul(localToRoot, localMatrix(for: localTransform))
         for childId in getEntityChildren(parentId: entityId) {
+            let childLocalToRoot: simd_float4x4
+            if let childLocalTransform = scene.get(component: LocalTransformComponent.self, for: childId) {
+                childLocalToRoot = simd_mul(localToRoot, localMatrix(for: childLocalTransform))
+            } else {
+                childLocalToRoot = localToRoot
+            }
             accumulateBoundsInRootSpace(
                 entityId: childId,
                 localToRoot: childLocalToRoot,
@@ -597,8 +602,13 @@ class SelectionManager: ObservableObject {
             }
         }
 
-        let childLocalToRoot = simd_mul(localToRoot, localMatrix(for: localTransform))
         for childId in getEntityChildren(parentId: entityId) {
+            let childLocalToRoot: simd_float4x4
+            if let childLocalTransform = scene.get(component: LocalTransformComponent.self, for: childId) {
+                childLocalToRoot = simd_mul(localToRoot, localMatrix(for: childLocalTransform))
+            } else {
+                childLocalToRoot = localToRoot
+            }
             accumulateRenderableBoundsInRootSpace(
                 entityId: childId,
                 localToRoot: childLocalToRoot,
diff --git a/Tests/UntoldEditorTests/SelectionSeveralTests.swift b/Tests/UntoldEditorTests/SelectionSeveralTests.swift
index a56d07a..71704e8 100644
--- a/Tests/UntoldEditorTests/SelectionSeveralTests.swift
+++ b/Tests/UntoldEditorTests/SelectionSeveralTests.swift
@@ -477,4 +477,48 @@ final class SelectionSeveralTests: XCTestCase {
         assertNearlyEqual(framing.min, simd_float3(-0.5, -0.5, -0.5))
         assertNearlyEqual(framing.max, simd_float3(0.5, 10.5, 0.5))
     }
+
+    // MARK: - Single selection's live highlight box, with a mesh on a child
+
+    /// A container entity, as the asset root a drag from the Asset Browser
+    /// creates: it has a place in the scene but draws nothing itself.
+    private func makeContainer(_ name: String, at position: simd_float3) -> EntityID {
+        let entity = createEntity()
+        setEntityName(entityId: entity, name: name)
+        registerTransformComponent(entityId: entity)
+        registerSceneGraphComponent(entityId: entity)
+        translateTo(entityId: entity, position: position)
+        return entity
+    }
+
+    /// What `updateBoundingBoxBuffer` last wrote: the min/max of the eight
+    /// distinct corners among its 24 line-endpoint vertices.
+    private func writtenBoxBounds() throws -> (min: simd_float3, max: simd_float3) {
+        let buffer = try XCTUnwrap(bufferResources.boundingBoxBuffer)
+        let vertices = buffer.contents().bindMemory(to: simd_float4.self, capacity: boundingBoxVertexCount)
+        var minBounds = simd_float3(repeating: .greatestFiniteMagnitude)
+        var maxBounds = simd_float3(repeating: -.greatestFiniteMagnitude)
+        for index in 0 ..< boundingBoxVertexCount {
+            let v = vertices[index]
+            let point = simd_float3(v.x, v.y, v.z)
+            minBounds = simd_min(minBounds, point)
+            maxBounds = simd_max(maxBounds, point)
+        }
+        return (minBounds, maxBounds)
+    }
+
+    /// Selecting a dragged-in asset's root through the scenegraph highlights
+    /// the box around its mesh, which lives on a child with its own offset
+    /// from the root — not the box the root would have at its own origin.
+    func test_selectingAContainer_highlightsItsOffsetChildsMesh() throws {
+        let root = makeContainer("GoalpostRoot", at: simd_float3(10, 0, 0))
+        let mesh = makeBox("Crossbar", at: simd_float3(0, 3, 0))
+        setParent(childId: mesh, parentId: root)
+
+        selectionManager.selectEntity(entityId: root)
+
+        let written = try writtenBoxBounds()
+        assertNearlyEqual(written.min, simd_float3(-0.5, 2.5, -0.5))
+        assertNearlyEqual(written.max, simd_float3(0.5, 3.5, 0.5))
+    }
 }