v0.3.1

Fixed

• ioviewer: an output that cannot be written (a locked file, a read-only folder, a folder where the file should be or
  a file where its folder should be) ends the run with Error: Failed to export and exit code 3 for the page, the
  JSON output and the --json file alike. Before, only the page caught rejected data, and an I/O error ended the tool
  with an unhandled exception.
• ioviewer --serve: when the preview server cannot start (a port in use or out of range) or fails while serving, the
  tool exits with the new code 5 after printing the error; the output has been written. Before, it exited with 0, or 4
  for an engine error.
• JsonViewerExporter.Save serializes the data once before it opens the file, so data the serializer rejects (such as
  a non-finite coordinate) leaves an existing file as it was, as the HTML export already did; before, the file was
  emptied first. The file is still rewritten in place and keeps its permissions. The JSON outputs of ioviewer
  (-o *.json, --json) get this too, and its export error names the output that failed:
  Error: Failed to export '<input>' to '<output>': ....

v0.3.0

Version 0.3.0 builds the viewer on the scene model of the IOScene package
(IOScene [0.1.0, 0.2.0-0.0), a new dependency of the IOViewer package). This is a breaking change of the
library API. What breaks for existing users:

1. The model types move to namespace IOScene with Scene* names, ViewerClash* included; doc.Elements becomes
   doc.Scene.Elements, and the members in the table below change.
2. The documented quick start (a ViewerMesh with its own vertices) becomes SceneDocument.AddMesh.
3. Written JSON has a new shape. IOViewer 0.2.0 reads a 0.3.0 file as an empty document with exit code 0, because it
   ignores unknown members.
4. A page regenerated from an old snapshot shows each mesh without an element as an element (in the element count, the
   tree and hide).

Not broken: loading 0.1/0.2 JSON, existing HTML pages, the ioviewer arguments, the importer to exporter pipeline
(GlbViewerImporter to HtmlViewerExporter, ViewerDocument.Title) and the one-package install (IOScene comes with
the IOViewer package). The IOViewer.Cli tool only gains inputs.

Migration from 0.2.0

0.2.0 (IOViewer.Model)	0.3.0
Vector2d, Vector3d, BoundingBox3d, Transform3d, RgbaColor	the same names in namespace IOScene
Vector4d, Quaterniond	removed, no replacement
ViewerDocument.Elements, Meshes, Geometries, Materials, Textures, Viewpoints, ClashTests	ViewerDocument.Scene.Elements, Instances, Geometries, Materials, Textures, Viewpoints, ClashTests
ViewerDocument.SourcePath, Author, CreatedAt, Application	Scene.Models[0].Path, Author, CreatedAt, Application
ViewerDocument.Grids (one grid system)	Scene.Grids (a list of SceneGridSystem, each with ModelId)
ViewerDocument.TimeLiner	Scene.Schedules (a list of SceneSchedule)
ViewerDocument.LinkedFiles (ViewerLinkedFile Name, Path, Visible)	Scene.Models (SceneModel with a unique Key, Name, Path); Visible = false is the model's key in ViewerDocument.HiddenModelKeys
ViewerDocument.BoundingBox, ComputeBoundingBox()	Scene.ComputeBounds()
ViewerDocument.Title (default 3D BIM Model)	kept; it reads and writes Scene.Title (default empty)
ViewerDocument.SectionPlanes, SectionBox, ViewerSectionPlane, ViewerSectionBox	kept; their Vector3d is IOScene.Vector3d
-	ViewerDocument.Scene, ViewerDocument.HiddenModelKeys, new ViewerDocument(SceneDocument)
ViewerElement	SceneElement
ViewerElement.LinkName	SceneElement.ModelId, the id of a SceneModel
ViewerElement.Level (a string)	SceneElement.LevelId, the id of a SceneLevel in Scene.Levels
ViewerElement.Properties, AddProperty(group, name, value)	ScenePropertySet in Scene.PropertySets (Name = group), referenced by SceneElement.PropertySetIds; each SceneProperty has a SceneValue (SceneValue.FromText for a string)
ViewerElement.MeshIndices, ViewerElement.BoundingBox	removed; SceneInstance.ElementId links an element to its geometry
ViewerMesh	SceneInstance, which places a SceneGeometry for an element
ViewerMesh.Vertices, Indices, Normals, UVs (own geometry)	a SceneGeometry placed by one instance; SceneDocument.AddMesh adds both and the element
ViewerMesh.ElementId (optional)	SceneInstance.ElementId (required: every instance belongs to an element)
ViewerMesh.GeometryId, Transform, MaterialId, Name	SceneInstance.GeometryId, Transform, MaterialId, Name
ViewerMesh.Color, ViewerMesh.Opacity, ViewerMaterial.Opacity	the alpha of SceneInstance.Color or SceneMaterial.Color, the only opacity
ViewerMesh.TextureIndex, ViewerMaterial.TextureIndex	SceneMaterial.TextureId, the id of a SceneTexture
ViewerMesh.Id, BoundingBox, ComputeBoundingBox()	removed
ViewerGeometry	SceneGeometry, with Topology (Triangles, Lines, Points); empty Indices means non-indexed
ViewerMaterial	SceneMaterial
ViewerTexture (Base64Data string)	SceneTexture (Data bytes)
ViewerGridSystem, ViewerGridLine	SceneGridSystem, SceneGridLine
ViewerViewpoint, ViewerCamera, ViewerProjection	SceneViewpoint, SceneCamera, SceneProjection
ViewerTimeLinerSchedule	SceneSchedule; GetOverallStart() and GetOverallEnd() are removed
ViewerTimeLinerTask, ViewerTimeLinerTaskType	SceneTask, SceneTaskType
ViewerTimeLinerTask.AttachedElementIds	SceneTask.ElementIds
ViewerTimeLinerTask.AttachedSetName	removed
ViewerClashTest, ViewerClashResult, ViewerClashStatus	SceneClashTest, SceneClashResult, SceneClashStatus
ViewerClashResult.Distance (double)	SceneClashResult.Distance (double?, null when the source does not report it)
constructors with parameters (new ViewerViewpoint(name, camera) and others)	object initializers

Added

• HtmlViewerExporter.Save, Export and ExportToString take a SceneDocument too.
• JsonViewerImporter and the ioviewer tool read three kinds of JSON: viewer JSON ("Kind": "ioviewer"), IOScene
  scene files ("Kind": "ioscene") and IOViewer 0.1/0.2 snapshots (no Kind). In a snapshot, meshes that share an
  ElementId no element has get one element with that id, and each other mesh without an element gets one of its own.
  A newer format, a missing or wrong Format and an unknown kind are rejected with InvalidDataException.
• The HTML viewer shows SceneElement.SourceId, the element's id in its source format (such as a Revit UniqueId or an
  IFC GlobalId), as its own row in the properties panel ("Source ID" / "ID источника"), and the model tree search finds
  it. It is written to the page's element list only when set.
• The ioviewer tool reads IFC (.ifc, .ifczip) through IfcIO.Scene 0.11.1 and Revit (.rvt) through
  RvtIO.Scene 0.4.0. The model key is the file name; the title is the IFC project name, or the Revit file name. What
  the engine could not convert (such as an element without geometry) is printed to standard error as one warning or
  error per kind with its count. When the engine reported an error (elements may be missing), the requested output
  (the page, the JSON or both) is still written and the tool exits with code 4. The IOViewer library still references no engine; only the IOViewer.Cli tool
  package ships IfcIO, RvtIO and their dependencies (see THIRD-PARTY-NOTICES.md).

Changed

• JsonViewerExporter writes viewer JSON format 2: { "Kind": "ioviewer", "Format": 2, "Scene", "SectionPlanes", "SectionBox", "HiddenModelKeys" }, with the scene in the encoding of IOScene's SceneJson.
• GlbViewerImporter and ObjViewerImporter return documents whose scene has one model and passes
  SceneDocument.Validate().
• The viewer draws triangles only: instances of line or point geometry are skipped, and the ioviewer tool prints a
  warning with their number.
• Opacity is a colour alpha byte, so an opacity that is not a multiple of 1/255 is rounded (0.35 becomes 89/255).
• In an IOViewer 0.1/0.2 snapshot, an element LinkName that matches no linked file becomes a model of the scene, so
  a page made from the snapshot lists it in the linked files panel, where its elements can be hidden.
• The documentation states the model's units and axes: all coordinates and lengths are in metres, with Z up.
• A clash distance is nullable. The page writes null for a distance the source does not report and the clash list
  shows no distance for it, where it showed 0. A 0.1/0.2 snapshot keeps the distance it has (0 when it has none).
• GlbViewerImporter converts a material's base colour factor from glTF's linear values to sRGB. Imported GLB colours
  look lighter than in 0.2.0, which is now correct. The alpha stays linear; every channel is now rounded to the nearest
  byte, where it was truncated.
• A 4D task of a type this version does not know is shown as a construct task; it was left out of the schedule.
• The properties panel shows the property sets of an element that have the same name as one group, and a property name
  that repeats in a group gets a numbered suffix (Height (2)), so no property is lost. Elements that share an id,
  which SceneDocument.Validate() rejects, show the properties of all of them.

v0.2.0

Fixed

• JsonViewerImporter keeps grid lines, 4D tasks with their attached element ids and child tasks, clash results,
  element properties and element mesh indices; they were silently dropped on load.
• The IOViewer package now includes the XML documentation file, so existing API comments show in IntelliSense.
• The release workflow runs only for version tags again, fails on any gh release error and no longer overwrites assets of an existing release.
• tools/pack-release.ps1 fails when creating the source archive fails.
• Documentation no longer claims .mtl material support or mesh simplification, neither of which exists.
• The logo on the documentation site no longer covers half of the page; it is sized to the navigation bar.
• GlbViewerImporter and ObjViewerImporter create elements: one ViewerElement per GLB node that draws a mesh
  (category GLB) and per OBJ object or group (category OBJ), so converted models have a model tree and can be
  selected, hidden and isolated. Each OBJ mesh keeps only the vertices its faces use instead of every vertex read so
  far, and a face that references a vertex not yet read throws InvalidDataException on load.
• A document without elements (built through the API or loaded from older JSON) can still be listed, selected, hidden
  and isolated in the HTML viewer: meshes that share an ElementId appear as one element with that id, which 4D tasks
  and clashes match, and each other mesh appears on its own with its mesh id and name, as in 0.1.0. The document itself
  is not changed.

Added

• A new HTML viewer built on three.js 0.186.1, embedded in the page, which still works offline without network requests:
  • floating panels (model tree with search, properties, views, sections, clashes, 4D, linked files), a toolbar with
    labelled groups, a status bar with selected and total counts, and a context menu;
  • Navisworks-style mouse: orbit around the point under the cursor, pan with the middle or right button, zoom to the
    cursor, Ctrl+click, window (left to right) and crossing (right to left) box selection; hotkeys H, I, Shift+H, F, Esc;
  • a view cube drawn from the camera orientation, with face clicks, 90° arrows and a home button;
  • up to six section planes moved and rotated with an in-scene gizmo, or a section box that keeps or cuts its inside,
    with face handles, a centre handle and a box around the selection;
  • distance measurement, display modes (materials, textures, white, wireframe), grid lines, global opacity,
    perspective or orthographic camera and fullscreen;
  • saved viewpoints with a tour, a clash list that flies to the clash and selects both elements, a 4D schedule player
    and linked-file visibility;
  • Russian or English interface, chosen from the browser language;
  • a message instead of a blank page when the browser has no WebGL 2, the model data cannot be read, the graphics
    context is lost or the model has more objects than the GPU can address.
• Shared geometry: ViewerDocument.Geometries, ViewerGeometry, ViewerMesh.GeometryId, ViewerMesh.Transform and
  the Transform3d affine transform. The HTML exporter writes each shared geometry once and also writes meshes that
  are exact translated copies of each other once.
• ViewerClashResult.Element1Id and Element2Id. The viewer selects clashing elements by Id, and by name only when the
  name is unique.
• The HTML exporter writes the projection of saved viewpoints, so orthographic viewpoints open orthographic.
• THIRD-PARTY-NOTICES.md with the three.js license, included in the NuGet packages and the release archives.
• A CI job for the viewer: it rebuilds the bundle, checks that the committed dist/viewer.js matches the sources and
  runs the unit and Playwright end-to-end tests. Dependabot also updates the viewer's npm packages.
• Links to the DeepWiki overview of the repository in the README and on the documentation site.

Changed

• GlbViewerImporter keeps node transforms and shared meshes (one ViewerGeometry per mesh primitive, one
  ViewerMesh per node that uses it) and converts glTF's Y-up to the viewer's Z-up, so GLB models no longer lie on
  their side. A node hierarchy that is not a tree (a node referenced twice, or a cycle) now throws
  InvalidDataException.
• HtmlViewerExporter throws InvalidDataException for indices outside a mesh's or geometry's vertices, a
  GeometryId that is not in the document, a duplicate geometry id or a mesh with both a GeometryId and its own
  vertices, instead of writing broken geometry. Save checks these references before it opens the file, so reference
  validation failures leave an existing file as it was, and the CLI reports such input with exit code 3.
• HtmlViewerOptions.MaxMeshVertices defaults to no limit (was 5,000,000) and no longer cuts the model silently: when a
  lower limit leaves meshes out, the viewer shows a banner with the number of meshes written.
• The HTML payload uses format 3: one base64 binary block, positions quantized to 16-bit steps of 2⁻¹⁰ m (error at most
  0.49 mm, 0.85 mm for rotated shared geometry) and octahedral 16-bit normals. Geometry larger than about 64 m, and
  shared geometry that any instance scales up, stays 32-bit float. For a real 746 MB IFC water-supply model (via GLB)
  the page is 44.4 MB, about the size 0.1.0 wrote (44.1 MB) although it now also carries normals; with
  32-bit float positions and normals it would be 57.5 MB. The HTML is written to the output stream as it is produced.
• The viewer merges geometry into spatial chunks per material and keeps per-object state (hidden, selected, tint) in a
  texture, so hide, isolate, selection and 4D colouring never rebuild geometry. When merged data would exceed
  384 MiB, repeated shapes are drawn as instanced copies in spatially bounded cells instead.
• Measured on an integrated 2-CU AMD GPU: a model of 200,000 elements and 19.2 million triangles opens in about 1.3 s,
  orbits at 30 fps at full detail (60 fps on an RTX 4080), draws a full frame in 30.3 ms and shows a click, hide or
  show all in about 52 ms, using about 327 MB of GPU memory. A model of 1,000,000 elements opens in about 2.2 s, draws
  a full frame in 0.21 s and uses about 88 MB of GPU memory; it orbits at 20 fps (95th percentile), picking an object
  takes about 22 ms and a still frame costs about 23 ms of CPU time.
• Transparent objects are sorted back to front per chunk or cell, not per object.
• Package descriptions and documentation say "no external dependencies, works offline" instead of "zero-dependency".
• Tests run on both .NET 8 and .NET 10.
• global.json, CI workflows and repository settings follow the shared IOExtend conventions: SDK 10.0.100 without prerelease, NuGet vulnerability audit, Dependabot, LF line endings, issue and pull request templates.
• Copyright holder is mahach666 in the license, package metadata and README.
• README and documentation state that IOViewer is not affiliated with Autodesk.
• SECURITY.md and CONTRIBUTING.md describe supported versions, security scope, development setup and the clean-room policy.
• CONTRIBUTING.md describes the viewer toolchain (Node.js 24, npm ci, npm run build, npm test, npm run e2e,
  manual npm run perf).

Removed

• The turntable (automatic 360° rotation) of the old viewer.
• The previous hand-written WebGL viewer template, replaced by the three.js viewer.

Known limitations

• HtmlViewerExporter.Save can truncate an existing output file before rejecting NaN or infinity in coordinates or
  metadata. Output replacement is not atomic.

IOViewer v0.1.0

Initial Release

• Pure Managed 3D BIM & CAD Viewer Library (IOViewer):
  • Independent intermediate BIM/CAD document representation (ViewerDocument, ViewerElement, ViewerMesh, ViewerMaterial, ViewerTexture).
  • Standalone, zero-dependency self-contained interactive 3D WebGL HTML Viewer exporter (HtmlViewerExporter).
  • Packed binary Base64 geometry encoding (Float32Array positions and Uint32Array/Uint16Array indices) for ~3x payload reduction over JSON.
  • Relative-To-Center (RTC) coordinate shifting to eliminate WebGL 32-bit floating point precision jitter on large georeferenced coordinates.
  • Interactive 3D ViewCube with orientation faces and directional navigation arrows.
  • Sectioning Suite:
    • Arbitrary section planes with interactive in-scene 3D normal drag gizmo manipulator and direction flip.
    • 6-sided Section Box (bounding box volume, interactive scaling slider, fit-to-selection, and invert clipping mode).
  • Display Modes: Material colors with opacity, Diffuse Textures with real-world UV box projection, White/Clay architectural model, Wireframe, and global scene opacity slider.
  • BIM Data Hierarchy & Navigation: Category tree with element counts, Linked files panel, instant search with autocomplete and camera focus, properties inspector panel, and selection actions (Isolate, Hide, Show All).
  • Coordination & Spatial Tools: 3D spatial grids projection, interactive 3D point-to-point measurement, 4D TimeLiner schedule simulation player with status coloring, and clash detection inspection.
  • Camera Animations: Cubic Ease-In-Out transitions, Turntable 360° presentation orbit, and Saved Viewpoints Walkthrough Tour player.
• File Format Importers:
  • GlbViewerImporter: Load binary glTF 2.0 models (.glb) directly into ViewerDocument.
  • ObjViewerImporter: Load Wavefront OBJ models (.obj) into ViewerDocument.
  • JsonViewerImporter: Load structured JSON model snapshots into ViewerDocument.
• Command Line Interface (ioviewer):
  • Convert GLB, OBJ, or JSON into self-contained HTML viewers.
  • Optional built-in HTTP preview server (--serve).