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Implement KHR_materials_variants gltf extension #8

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merged 2 commits into from
May 23, 2024
Merged

Implement KHR_materials_variants gltf extension #8

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f497e7d
Create a helper for reading a list of objects
B3zaleel May 23, 2024
d3b9771
Implement the KHR_materials_variants glTF extension
B3zaleel May 23, 2024
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298 changes: 298 additions & 0 deletions src/ThreeDModels/Format/Gltf/Extensions/KHR_materials_variants.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,298 @@
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;

public class KHR_materials_variants : IGltfProperty
{
/// <summary>
/// A list of objects defining a valid material variant.
/// </summary>
public required List<KhrMaterialsVariantsVariant> Variants { get; set; }
public Dictionary<string, object?>? Extensions { get; set; }
public object? Extras { get; set; }
}

/// <summary>
/// Represents an object defining a valid material variant.
/// </summary>
public class KhrMaterialsVariantsVariant : IGltfRootProperty
{
/// <summary>
/// The name of the material variant.
/// </summary>
public string? Name { get; set; }
public Dictionary<string, object?>? Extensions { get; set; }
public object? Extras { get; set; }
}

public class KHR_materials_variants_mesh_primitive : IGltfProperty
{
/// <summary>
/// A list of material to variant mappings.
/// </summary>
public required List<KhrMaterialsVariantsMapping>? Mappings { get; set; }
public Dictionary<string, object?>? Extensions { get; set; }
public object? Extras { get; set; }
}

/// <summary>
/// Represents a mapping of an indexed material to a set of variants.
/// </summary>
public class KhrMaterialsVariantsMapping : IGltfProperty
{
/// <summary>
/// A list of variant index values.
/// </summary>
public required List<int> Variants { get; set; }
/// <summary>
/// The material associated with the set of variants.
/// </summary>
public required int Material { get; set; }
/// <summary>
/// The user-defined name of this variant material mapping.
/// </summary>
public string? Name { get; set; }
public Dictionary<string, object?>? Extensions { get; set; }
public object? Extras { get; set; }
}

public class KhrMaterialsVariantsExtension : IGltfExtension
{
public string Name => nameof(KHR_materials_variants);

public object? Read(ref Utf8JsonReader jsonReader, GltfReaderContext context, Type parentType)
{
if (parentType != typeof(Gltf))
{
List<KhrMaterialsVariantsVariant>? variants = 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(variants))
{
variants = ReadObjectList(ref jsonReader, context, (ref Utf8JsonReader reader, GltfReaderContext ctx) => KhrMaterialsVariantsVariantSerialization.Read(ref reader, ctx)!);
}
else if (propertyName == nameof(extensions))
{
extensions = ExtensionsSerialization.Read<KHR_draco_mesh_compression>(ref jsonReader, context);
}
else if (propertyName == nameof(extras))
{
extras = ExtrasSerialization.Read(ref jsonReader, context);
}
else
{
throw new InvalidDataException($"Unknown property: {propertyName}");
}
}
if (variants == null || variants.Count < 1)
{
throw new InvalidDataException("KHR_materials_variants.variants must have at least one variant.");
}
return new KHR_materials_variants()
{
Variants = variants!,
Extensions = extensions,
Extras = extras,
};
}
else if (parentType == typeof(MeshPrimitive))
{
List<KhrMaterialsVariantsMapping>? mappings = null;
Dictionary<string, object?>? extensions = null;
object? extras = null;
if (jsonReader.TokenType == JsonTokenType.PropertyName && jsonReader.Read())
{
}
if (jsonReader.TokenType == JsonTokenType.Null)
{
return null;
}
else if (jsonReader.TokenType != JsonTokenType.StartObject)
{
throw new InvalidDataException("Failed to find start of property.");
}
while (jsonReader.Read())
{
if (jsonReader.TokenType == JsonTokenType.EndObject)
{
break;
}
var propertyName = jsonReader.GetString();
if (propertyName == nameof(mappings))
{
mappings = ReadObjectList(ref jsonReader, context, (ref Utf8JsonReader reader, GltfReaderContext ctx) => KhrMaterialsVariantsMappingSerialization.Read(ref reader, ctx)!);
}
else if (propertyName == nameof(extensions))
{
extensions = ExtensionsSerialization.Read<KHR_draco_mesh_compression>(ref jsonReader, context);
}
else if (propertyName == nameof(extras))
{
extras = ExtrasSerialization.Read(ref jsonReader, context);
}
else
{
throw new InvalidDataException($"Unknown property: {propertyName}");
}
}
if (mappings == null || mappings.Count < 1)
{
throw new InvalidDataException("KHR_materials_variants.mappings must have at least 1 mapping.");
}
return new KHR_materials_variants_mesh_primitive()
{
Mappings = mappings!,
Extensions = extensions,
Extras = extras,
};
}
throw new InvalidDataException("KHR_materials_variants must be used in a either the Gltf root or a MeshPrimitive.");
}
}

public class KhrMaterialsVariantsVariantSerialization
{
public static KhrMaterialsVariantsVariant? Read(ref Utf8JsonReader jsonReader, GltfReaderContext context)
{
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(name))
{
name = ReadString(ref jsonReader);
}
else if (propertyName == nameof(extensions))
{
extensions = ExtensionsSerialization.Read<AccessorSparse>(ref jsonReader, context);
}
else if (propertyName == nameof(extras))
{
extras = ExtrasSerialization.Read(ref jsonReader, context);
}
else
{
throw new InvalidDataException($"Unknown property: {propertyName}");
}
}
if (name == null)
{
throw new InvalidDataException("KhrMaterialsVariantsVariant.name is a required property.");
}
return new()
{
Name = name!,
Extensions = extensions,
Extras = extras,
};
}
}

public class KhrMaterialsVariantsMappingSerialization
{
public static KhrMaterialsVariantsMapping? Read(ref Utf8JsonReader jsonReader, GltfReaderContext context)
{
List<int>? variants = null;
int? material = 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(variants))
{
variants = ReadIntegerList(ref jsonReader, context);
}
else if (propertyName == nameof(material))
{
material = ReadInteger(ref jsonReader);
}
else if (propertyName == nameof(name))
{
name = ReadString(ref jsonReader);
}
else if (propertyName == nameof(extensions))
{
extensions = ExtensionsSerialization.Read<AccessorSparse>(ref jsonReader, context);
}
else if (propertyName == nameof(extras))
{
extras = ExtrasSerialization.Read(ref jsonReader, context);
}
else
{
throw new InvalidDataException($"Unknown property: {propertyName}");
}
}
if (variants == null || variants.Count < 1)
{
throw new InvalidDataException("KHR_materials_variants.mappings[i].variants must have at least one variant.");
}
if (material == null)
{
throw new InvalidDataException("KHR_materials_variants.mappings[i].material is a required property.");
}
return new()
{
Variants = variants!,
Material = (int)material!,
Name = name,
Extensions = extensions,
Extras = extras,
};
}
}
5 changes: 5 additions & 0 deletions src/ThreeDModels/Format/Gltf/IO/Utf8JsonReaderHelpers.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,4 +91,9 @@ public static class Utf8JsonReaderHelpers
{
return ReadList(ref jsonReader, context, JsonTokenType.Number, (ref Utf8JsonReader reader, GltfReaderContext _) => (float)ReadFloat(ref reader)!);
}

public static List<T>? ReadObjectList<T>(ref Utf8JsonReader jsonReader, GltfReaderContext context, ArrayElementReader<T> elementReader)
{
return ReadList(ref jsonReader, context, JsonTokenType.StartObject, elementReader);
}
}
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