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CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is a VRML97 (Virtual Reality Modeling Language) parser implementation in C#. It parses 3D scene descriptions conforming to the VRML97 specification (http://tecfa.unige.ch/guides/vrml/vrml97/spec/).

Build and Test Commands

Build the solution

dotnet build Graph3D.Vrml.sln

Run all tests

dotnet test Graph3D.Vrml.Test/Graph3D.Vrml.Test.csproj

Run a specific test

dotnet test Graph3D.Vrml.Test/Graph3D.Vrml.Test.csproj --filter "FullyQualifiedName~VRMLTokenizerTest.TokenizerTest"

Build for release

dotnet build Graph3D.Vrml.sln -c Release

Architecture

Parser Pipeline

The parsing process follows a two-stage pipeline:

  1. Tokenization (Graph3D.Vrml/Tokenizer/): Converts VRML text into tokens using a state machine pattern

    • Vrml97Tokenizer is the main tokenizer entry point
    • Different states handle numbers, strings, comments, punctuation, etc.
    • Produces VRML97Token objects with types defined in VRML97TokenType

  2. Parsing (Graph3D.Vrml/Parser/): Converts tokens into a scene graph

    • VrmlParser orchestrates the parsing process
    • ParserContext maintains parsing state, named node registry, and field/node container stacks
    • FieldParser handles field value parsing
    • NodeFactory creates node instances from type identifiers

Node Hierarchy

All VRML nodes inherit from BaseNode (Graph3D.Vrml/Nodes/BaseNode.cs):

  • Manages fields, exposed fields, event inputs/outputs via dictionaries
  • Supports node naming, parent tracking, cloning
  • Uses visitor pattern for traversal (INodeVisitor)

Node categories in Graph3D.Vrml/Nodes/:

  • Grouping (Grouping/): Transform, Group, Anchor - nodes that contain children
  • Geometry (Geometry/): Box, Sphere, Cone, Cylinder, IndexedFaceSet, etc.
  • Appearance (Appearance/): Material, Texture nodes, TextureTransform
  • Bindable (Bindable/): Viewpoint, NavigationInfo, Background
  • Light Sources (LightSources/): DirectionalLight, PointLight
  • Sensors (Sensors/): TimeSensor and other interaction nodes
  • Interpolation (Interpolation/): Animation interpolators

Field System

Fields represent node properties (Graph3D.Vrml/Fields/):

  • SF (Single-valued): SFBool, SFColor, SFFloat, SFInt32, SFNode, SFRotation, SFString, SFTime, SFVec2f, SFVec3f, SFImage
  • MF (Multi-valued): MFColor, MFFloat, MFInt32, MFNode, MFRotation, MFString, MFVec2f, MFVec3f
  • All inherit from Field base class
  • Use visitor pattern (IFieldVisitor) for type-safe field operations
  • Access types defined in FieldAccessType: Field, ExposedField, EventIn, EventOut

Scene Graph

Entry point is VrmlScene which contains a root SceneGraphNode. The parser populates this tree structure by:

  1. Creating nodes via NodeFactory
  2. Registering named nodes (DEF) in ParserContext.namedNodes
  3. Resolving node references (USE) during parsing
  4. Supporting PROTO/EXTERNPROTO for custom node types

Target Frameworks

  • Main library: net9.0
  • Test project: net9.0

Test Structure

Tests are in Graph3D.Vrml.Test/ and use NUnit. Test VRML files (.wrl) are embedded resources:

  • D2.wrl, D3.wrl, D4.wrl - Examples from VRML97 specification
  • Ant.WRL - Large example file for comprehensive testing
  • rose.wrl - Additional test scene

Tests are organized by functionality matching the source structure (e.g., Parser/Nodes/Geometry/BoxNodeTest.cs).