Recompute mesh world bounds and grid intersections after changes

src/NwcIO/Model/Grids/NwcGridSystem.cs

@@ -17,8 +17,6 @@ public sealed class NwcGridSystem
 
     public List<NwcGridLine> Lines { get; } = [];
 
-    private List<NwcGridIntersection>? _cachedIntersections;
-
     public NwcGridSystem() { }
 
     public NwcGridSystem(string name)
@@ -33,7 +31,6 @@ public NwcGridLine AddLine(NwcGridLine line)
     {
         ArgumentNullException.ThrowIfNull(line);
         Lines.Add(line);
-        _cachedIntersections = null;
         return line;
     }
 
@@ -51,11 +48,6 @@ public NwcGridLine AddLine(string name, Vector3d start, Vector3d end, double ele
     /// </summary>
     public IReadOnlyList<NwcGridIntersection> GetIntersections()
     {
-        if (_cachedIntersections is not null)
-        {
-            return _cachedIntersections;
-        }
-
         var result = new List<NwcGridIntersection>();
 
         for (int i = 0; i < Lines.Count; i++)
@@ -78,7 +70,6 @@ public IReadOnlyList<NwcGridIntersection> GetIntersections()
             }
         }
 
-        _cachedIntersections = result;
         return result;
     }
 

src/NwcIO/Model/NwcMesh.cs

@@ -23,7 +23,15 @@ public sealed class NwcMesh
     public BoundingBox3d? BoundingBox { get; init; }
 
     /// <summary>Optional 3D world transformation associated with this mesh instance.</summary>
-    public NwcTransform? Transform { get; set; }
+    public NwcTransform? Transform
+    {
+        get => _transform;
+        set
+        {
+            _transform = value;
+            _cachedWorldBounds = null;
+        }
+    }
 
     /// <summary>Surface material and color assigned to this mesh.</summary>
     public NwcMaterial? Material { get; set; }
@@ -34,6 +42,7 @@ public sealed class NwcMesh
     /// <summary>Number of triangle faces in this mesh.</summary>
     public int TriangleCount => Indices.Count / 3;
 
+    private NwcTransform? _transform;
     private BoundingBox3d? _cachedWorldBounds;
 
     /// <summary>

tests/NwcIO.Tests/GridSystemTests.cs

@@ -7,6 +7,68 @@ namespace NwcIO.Tests;
 
 public sealed class GridSystemTests
 {
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public void GridSystem_AfterEndpointEdit_UpdatesIntersectionsAndLocation(bool editStart)
+    {
+        var grids = new NwcGridSystem();
+        var line = grids.AddLine("A", new Vector3d(0, -10, 0), new Vector3d(0, 10, 0));
+        grids.AddLine("B", new Vector3d(5, -10, 0), new Vector3d(5, 10, 0));
+        grids.AddLine("1", new Vector3d(-10, 0, 0), new Vector3d(20, 0, 0));
+        Assert.Equal(0.0, grids.GetIntersections()[0].IntersectionPoint.X);
+        Assert.Equal("B / 1", grids.FormatLocation(new Vector3d(5, 0, 0)));
+
+        if (editStart)
+        {
+            line.Start = new Vector3d(20, -10, 0);
+        }
+        else
+        {
+            line.End = new Vector3d(20, 10, 0);
+        }
+
+        var intersection = Assert.Single(grids.GetIntersections(), i => i.Line1Name == "A" && i.Line2Name == "1");
+        Assert.Equal(10.0, intersection.IntersectionPoint.X);
+        Assert.Equal(0.0, intersection.IntersectionPoint.Y);
+        Assert.Equal("A / 1", grids.FormatLocation(new Vector3d(10, 0, 0)));
+    }
+
+    [Fact]
+    public void GridSystem_AfterDirectLineAddition_UpdatesIntersectionsAndLocation()
+    {
+        var grids = new NwcGridSystem();
+        grids.AddLine("A", new Vector3d(0, -10, 0), new Vector3d(0, 10, 0));
+        grids.AddLine("1", new Vector3d(-10, 0, 0), new Vector3d(30, 0, 0));
+        Assert.Single(grids.GetIntersections());
+        Assert.Equal("A (+20.00m) / 1", grids.FormatLocation(new Vector3d(20, 0, 0)));
+
+        grids.Lines.Add(new NwcGridLine("B", new Vector3d(20, -10, 0), new Vector3d(20, 10, 0)));
+
+        Assert.Equal(2, grids.GetIntersections().Count);
+        var intersection = Assert.Single(grids.GetIntersections(), i => i.Line2Name == "B");
+        Assert.Equal(20.0, intersection.IntersectionPoint.X);
+        Assert.Equal("1 / B", grids.FormatLocation(new Vector3d(20, 0, 0)));
+    }
+
+    [Fact]
+    public void GridSystem_AfterDirectLineRemoval_UpdatesIntersectionsAndLocation()
+    {
+        var grids = new NwcGridSystem();
+        var line = grids.AddLine("A", new Vector3d(0, -10, 0), new Vector3d(0, 10, 0));
+        grids.AddLine("B", new Vector3d(20, -10, 0), new Vector3d(20, 10, 0));
+        grids.AddLine("1", new Vector3d(-10, 0, 0), new Vector3d(30, 0, 0));
+        Assert.Equal(2, grids.GetIntersections().Count);
+        Assert.Equal("A / 1", grids.FormatLocation(new Vector3d(0, 0, 0)));
+
+        Assert.True(grids.Lines.Remove(line));
+
+        var intersection = Assert.Single(grids.GetIntersections());
+        Assert.Equal("B / 1", intersection.DisplayName);
+        Assert.Equal(20.0, intersection.IntersectionPoint.X);
+        Assert.Equal("B (-20.00m) / 1", grids.FormatLocation(new Vector3d(0, 0, 0)));
+    }
+
     [Fact]
     public void GridLine_CalculatesDistanceAndIntersection()
     {

tests/NwcIO.Tests/MeshParserTests.cs

@@ -8,6 +8,56 @@ namespace NwcIO.Tests;
 
 public class MeshParserTests
 {
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public void Mesh_GetWorldBoundingBox_AfterTransformAssignment_UsesCurrentTransform(bool initiallyTransformed)
+    {
+        var mesh = new NwcMesh
+        {
+            Id = 1,
+            Vertices = [new Vector3d(0, 0, 0), new Vector3d(1, 2, 3)],
+            Indices = [],
+            BoundingBox = new BoundingBox3d(new Vector3d(0, 0, 0), new Vector3d(1, 2, 3)),
+            Transform = initiallyTransformed
+                ? new NwcTransform { Id = 1, Translation = new Vector3d(10, 20, 30) }
+                : null,
+        };
+
+        Assert.Equal(initiallyTransformed ? 10.0 : 0.0, mesh.GetWorldBoundingBox().Min.X);
+
+        mesh.Transform = new NwcTransform { Id = 2, Translation = new Vector3d(100, 200, 300) };
+
+        var bounds = mesh.GetWorldBoundingBox();
+        var vertices = mesh.GetWorldVertices();
+        Assert.Equal(new Vector3d(100, 200, 300), bounds.Min);
+        Assert.Equal(new Vector3d(101, 202, 303), bounds.Max);
+        Assert.Equal(vertices[0], bounds.Min);
+        Assert.Equal(vertices[1], bounds.Max);
+    }
+
+    [Fact]
+    public void Mesh_GetWorldBoundingBox_AfterTransformRemoval_UsesLocalBounds()
+    {
+        var mesh = new NwcMesh
+        {
+            Id = 1,
+            Vertices = [new Vector3d(0, 0, 0), new Vector3d(1, 2, 3)],
+            Indices = [],
+            BoundingBox = new BoundingBox3d(new Vector3d(0, 0, 0), new Vector3d(1, 2, 3)),
+            Transform = new NwcTransform { Id = 1, Translation = new Vector3d(100, 200, 300) },
+        };
+
+        Assert.Equal(100.0, mesh.GetWorldBoundingBox().Min.X);
+
+        mesh.Transform = null;
+
+        var bounds = mesh.GetWorldBoundingBox();
+        Assert.Equal(mesh.BoundingBox.Value, bounds);
+        Assert.Equal(mesh.GetWorldVertices()[0], bounds.Min);
+        Assert.Equal(mesh.GetWorldVertices()[1], bounds.Max);
+    }
+
     [Fact]
     public void Mesh_TriangleCountAndIndices_AreCalculatedCorrectly()
     {