Implement EXT_lights_ies Gltf extension

src/ThreeDModels/Format/Gltf/Extensions/EXT_lights_ies.cs

@@ -0,0 +1,267 @@
+using System.Text.Json;
+using ThreeDModels.Format.Gltf.Elements;
+using ThreeDModels.Format.Gltf.IO;
+using static ThreeDModels.Format.Gltf.IO.Utf8JsonReaderHelpers;
+
+namespace ThreeDModels.Format.Gltf.Extensions;
+
+/// <summary>
+/// Represents an object that defines instance attributes for a node with a mesh.
+/// </summary>
+public class EXT_lights_ies : IGltfProperty
+{
+    public List<ExtLightsIesLightProfile>? Lights { get; set; }
+    public Dictionary<string, object?>? Extensions { get; set; }
+    public object? Extras { get; set; }
+}
+
+/// <summary>
+/// Represents an IES light profile.
+/// </summary>
+public class ExtLightsIesLightProfile : IGltfRootProperty
+{
+    /// <summary>
+    /// The URI (or IRI) of the light profile.
+    /// </summary>
+    public string? Uri { get; set; }
+    /// <summary>
+    /// The light profile's media type.
+    /// </summary>
+    public string? MimeType { get; set; }
+    /// <summary>
+    /// The index of the bufferView that contains the IES light profile.
+    /// </summary>
+    public int? BufferView { get; set; }
+    public string? Name { get; set; }
+    public Dictionary<string, object?>? Extensions { get; set; }
+    public object? Extras { get; set; }
+}
+
+public class ExtLightsIesNode : IGltfProperty
+{
+    /// <summary>
+    /// The id of the light profile referenced by this node.
+    /// </summary>
+    public required int Light { get; set; }
+    /// <summary>
+    /// Non-negative factor to scale the light's intensity.
+    /// </summary>
+    public float Multiplier { get; set; }
+    /// <summary>
+    /// RGB value for the light's color in linear space.
+    /// </summary>
+    public float[]? Color { get; set; }
+    public Dictionary<string, object?>? Extensions { get; set; }
+    public object? Extras { get; set; }
+}
+
+public class ExtLightsIesExtension : IGltfExtension
+{
+    public string Name => nameof(EXT_lights_ies);
+    public const float Default_Multiplier = 1.0f;
+    public static readonly float[] Default_Color = [1.0f, 1.0f, 1.0f];
+
+    public object? Read(ref Utf8JsonReader jsonReader, GltfReaderContext context, Type parentType)
+    {
+        if (parentType == typeof(Gltf))
+        {
+            List<ExtLightsIesLightProfile>? lights = null;
+            Dictionary<string, object?>? extensions = null;
+            object? extras = null;
+            if (jsonReader.TokenType == JsonTokenType.PropertyName && jsonReader.Read())
+            {
+            }
+            if (jsonReader.TokenType == JsonTokenType.Null)
+            {
+                return null;
+            }
+            else if (jsonReader.TokenType != JsonTokenType.StartObject)
+            {
+                throw new InvalidDataException("Failed to find start of property.");
+            }
+            while (jsonReader.Read())
+            {
+                if (jsonReader.TokenType == JsonTokenType.EndObject)
+                {
+                    break;
+                }
+                var propertyName = jsonReader.GetString();
+                if (propertyName == nameof(lights))
+                {
+                    lights = ReadObjectList(ref jsonReader, context, (ref Utf8JsonReader reader, GltfReaderContext ctx) => ExtLightsIesLightProfileSerialization.Read(ref reader, ctx)!);
+                }
+                else if (propertyName == nameof(extensions))
+                {
+                    extensions = ExtensionsSerialization.Read<EXT_lights_ies>(ref jsonReader, context);
+                }
+                else if (propertyName == nameof(extras))
+                {
+                    extras = JsonSerialization.Read(ref jsonReader, context);
+                }
+                else
+                {
+                    throw new InvalidDataException($"Unknown property: {propertyName}");
+                }
+            }
+            if (lights == null || lights.Count == 0)
+            {
+                throw new InvalidDataException("EXT_lights_ies.lights must contain at least 1 light profile.");
+            }
+            return new EXT_lights_ies()
+            {
+                Lights = lights,
+                Extensions = extensions,
+                Extras = extras,
+            };
+        }
+        else if (parentType == typeof(Node))
+        {
+            int? light = null;
+            float? multiplier = null;
+            float[]? color = null;
+            Dictionary<string, object?>? extensions = null;
+            object? extras = null;
+            if (jsonReader.TokenType == JsonTokenType.PropertyName && jsonReader.Read())
+            {
+            }
+            if (jsonReader.TokenType == JsonTokenType.Null)
+            {
+                return null;
+            }
+            else if (jsonReader.TokenType != JsonTokenType.StartObject)
+            {
+                throw new InvalidDataException("Failed to find start of property.");
+            }
+            while (jsonReader.Read())
+            {
+                if (jsonReader.TokenType == JsonTokenType.EndObject)
+                {
+                    break;
+                }
+                var propertyName = jsonReader.GetString();
+                if (propertyName == nameof(light))
+                {
+                    light = ReadInteger(ref jsonReader);
+                }
+                else if (propertyName == nameof(multiplier))
+                {
+                    multiplier = ReadFloat(ref jsonReader);
+                }
+                else if (propertyName == nameof(color))
+                {
+                    color = ReadFloatList(ref jsonReader, context)?.ToArray();
+                }
+                else if (propertyName == nameof(extensions))
+                {
+                    extensions = ExtensionsSerialization.Read<ExtLightsIesNode>(ref jsonReader, context);
+                }
+                else if (propertyName == nameof(extras))
+                {
+                    extras = JsonSerialization.Read(ref jsonReader, context);
+                }
+                else
+                {
+                    throw new InvalidDataException($"Unknown property: {propertyName}");
+                }
+            }
+            if (light == null)
+            {
+                throw new InvalidDataException("nodes[i].EXT_lights_ies.light is a required property.");
+            }
+            if (color != null && color.Length != 3)
+            {
+                throw new InvalidDataException("nodes[i].EXT_lights_ies.color must have 3 elements.");
+            }
+            return new ExtLightsIesNode()
+            {
+                Light = (int)light,
+                Multiplier = multiplier ?? Default_Multiplier,
+                Color = color ?? Default_Color,
+                Extensions = extensions,
+                Extras = extras,
+            };
+        }
+        throw new InvalidDataException("EXT_lights_ies must be used in either a Gltf root or a Node.");
+    }
+}
+
+public class ExtLightsIesLightProfileSerialization
+{
+    public static ExtLightsIesLightProfile? Read(ref Utf8JsonReader jsonReader, GltfReaderContext context)
+    {
+        string? uri = null;
+        string? mimeType = null;
+        int? bufferView = null;
+        string? name = null;
+        Dictionary<string, object?>? extensions = null;
+        object? extras = null;
+        if (jsonReader.TokenType == JsonTokenType.PropertyName && jsonReader.Read())
+        {
+        }
+        if (jsonReader.TokenType == JsonTokenType.Null)
+        {
+            return null;
+        }
+        else if (jsonReader.TokenType != JsonTokenType.StartObject)
+        {
+            throw new InvalidDataException("Failed to find start of property.");
+        }
+        while (jsonReader.Read())
+        {
+            if (jsonReader.TokenType == JsonTokenType.EndObject)
+            {
+                break;
+            }
+            var propertyName = jsonReader.GetString();
+            if (propertyName == nameof(uri))
+            {
+                uri = ReadString(ref jsonReader);
+            }
+            else if (propertyName == nameof(mimeType))
+            {
+                mimeType = ReadString(ref jsonReader);
+            }
+            else if (propertyName == nameof(bufferView))
+            {
+                bufferView = ReadInteger(ref jsonReader);
+            }
+            else if (propertyName == nameof(name))
+            {
+                name = ReadString(ref jsonReader);
+            }
+            else if (propertyName == nameof(extensions))
+            {
+                extensions = ExtensionsSerialization.Read<ExtLightsIesLightProfile>(ref jsonReader, context);
+            }
+            else if (propertyName == nameof(extras))
+            {
+                extras = JsonSerialization.Read(ref jsonReader, context);
+            }
+            else
+            {
+                throw new InvalidDataException($"Unknown property: {propertyName}");
+            }
+        }
+        if (bufferView != null && mimeType == null)
+        {
+            throw new InvalidDataException("EXT_lights_ies.lights[i].bufferView requires EXT_lights_ies.lights[i].mimeType.");
+        }
+        if (uri != null && bufferView != null)
+        {
+            throw new InvalidDataException("EXT_lights_ies.lights[i].uri cannot be defined when EXT_lights_ies.lights[i].bufferView is defined.");
+        }
+        if (uri == null && bufferView == null)
+        {
+            throw new InvalidDataException("EXT_lights_ies.lights[i].uri or EXT_lights_ies.lights[i].bufferView is a required property.");
+        }
+        return new()
+        {
+            Uri = uri,
+            MimeType = mimeType,
+            BufferView = bufferView,
+            Name = name,
+            Extensions = extensions,
+            Extras = extras,
+        };
+    }
+}