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berttbertt
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initial coding KHR_gaussian_splatting
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‎build/SharpGLTF.codeGen.Extensions.Khronos/KHR_GaussianSplatting.cs‎

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using System;
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using System.Collections.Generic;
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using System.Text;
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using SharpGLTF.SchemaReflection;
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namespace SharpGLTF
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{
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class GaussianSplattingExtension : SchemaProcessor
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{
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private static string SchemaUri => KhronosExtensions.KhronosExtensionPath("KHR_gaussian_splatting", "mesh.primitive.KHR_gaussian_splatting.schema.json");
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private const string ExtensionRootClassName = "KHR_gaussian_splatting glTF Mesh Primitive Extension";
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public override IEnumerable<(string, SchemaType.Context)> ReadSchema()
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{
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var ctx = SchemaProcessing.LoadExtensionSchemaContext(SchemaUri);
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yield return ("ext.GaussianSplatting.g", ctx);
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}
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public override void PrepareTypes(CodeGen.CSharpEmitter newEmitter, SchemaType.Context ctx)
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{
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newEmitter.SetRuntimeName(ExtensionRootClassName, "GaussianSplatting");
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}
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}
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}

‎build/SharpGLTF.codeGen.Extensions.Khronos/KhronosExtensions.cs‎

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// gpu mesh instancing
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yield return new MeshGpuInstancingExtension();
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yield return new GaussianSplattingExtension();
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// textures
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yield return new TextureTransformExtension();

‎src/SharpGLTF.Core/README.md‎

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- [x] [KHR_lights_punctual](https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual)
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- [x] [KHR_mesh_quantization](https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_mesh_quantization)
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- [x] [EXT_mesh_gpu_instancing](https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Vendor/EXT_mesh_gpu_instancing)
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- [x] [KHR_gaussian_splatting](https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_gaussian_splatting)
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#### KHR_gaussian_splatting quick usage
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```c#
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var primitive = mesh.CreatePrimitive().WithIndicesAutomatic(PrimitiveType.POINTS);
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primitive.WithVertexAccessor("POSITION", positions);
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primitive.WithVertexAccessor(GaussianSplatting.AttributeRotation, rotations);
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primitive.WithVertexAccessor(GaussianSplatting.AttributeScale, scales);
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primitive.WithVertexAccessor(GaussianSplatting.AttributeOpacity, opacities);
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primitive.WithVertexAccessor(GaussianSplatting.AttributeSHDegree0Coef0, shDegree0);
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var gaussian = primitive.UseGaussianSplatting();
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gaussian.Kernel = GaussianSplatting.KernelEllipse;
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gaussian.ColorSpace = GaussianSplatting.ColorSpaceSrgbRec709Display;
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```
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- [x] [KHR_materials_pbrSpecularGlossiness](https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness)
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- This extension has been declared _obsolete_ by Khronos, in favour of KHR_materials_specular + KHR_materials_IOR

‎src/SharpGLTF.Core/Schema2/Generated/ext.GaussianSplatting.g.cs‎

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// <auto-generated/>
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//------------------------------------------------------------------------------------------------
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// This file has been programatically generated; DON´T EDIT!
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//------------------------------------------------------------------------------------------------
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#pragma warning disable SA1001
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#pragma warning disable SA1027
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#pragma warning disable SA1028
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#pragma warning disable SA1121
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#pragma warning disable SA1205
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#pragma warning disable SA1309
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#pragma warning disable SA1402
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#pragma warning disable SA1505
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#pragma warning disable SA1507
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#pragma warning disable SA1508
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#pragma warning disable SA1652
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Numerics;
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using System.Text.Json;
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using JSONREADER = System.Text.Json.Utf8JsonReader;
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using JSONWRITER = System.Text.Json.Utf8JsonWriter;
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using FIELDINFO = SharpGLTF.Reflection.FieldInfo;
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namespace SharpGLTF.Schema2
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{
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using Collections;
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/// <summary>
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/// Data defining a 3D Gaussian Splat primitive.
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/// </summary>
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#if NET6_0_OR_GREATER
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[System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembers(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.NonPublicConstructors | System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicConstructors)]
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#endif
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[global::System.CodeDom.Compiler.GeneratedCodeAttribute("SharpGLTF.CodeGen", "1.0.0.0")]
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partial class GaussianSplatting : ExtraProperties
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{
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#region reflection
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public new const string SCHEMANAME = "KHR_gaussian_splatting";
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protected override string GetSchemaName() => SCHEMANAME;
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protected override IEnumerable<string> ReflectFieldsNames()
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{
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yield return "colorSpace";
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yield return "kernel";
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yield return "projection";
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yield return "sortingMethod";
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foreach(var f in base.ReflectFieldsNames()) yield return f;
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}
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protected override bool TryReflectField(string name, out FIELDINFO value)
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{
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switch(name)
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{
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case "colorSpace": value = FIELDINFO.From("colorSpace",this, instance => instance._colorSpace); return true;
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case "kernel": value = FIELDINFO.From("kernel",this, instance => instance._kernel); return true;
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case "projection": value = FIELDINFO.From("projection",this, instance => instance._projection ?? "perspective"); return true;
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case "sortingMethod": value = FIELDINFO.From("sortingMethod",this, instance => instance._sortingMethod ?? "cameraDistance"); return true;
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default: return base.TryReflectField(name, out value);
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}
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}
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#endregion
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#region data
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private String _colorSpace;
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private String _kernel;
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private const String _projectionDefault = "perspective";
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private String _projection;
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private const String _sortingMethodDefault = "cameraDistance";
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private String _sortingMethod;
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#endregion
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#region serialization
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protected override void SerializeProperties(JSONWRITER writer)
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{
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base.SerializeProperties(writer);
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SerializeProperty(writer, "colorSpace", _colorSpace);
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SerializeProperty(writer, "kernel", _kernel);
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SerializeProperty(writer, "projection", _projection);
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SerializeProperty(writer, "sortingMethod", _sortingMethod);
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}
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protected override void DeserializeProperty(string jsonPropertyName, ref JSONREADER reader)
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{
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switch (jsonPropertyName)
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{
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case "colorSpace": DeserializePropertyValue<GaussianSplatting, String>(ref reader, this, out _colorSpace); break;
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case "kernel": DeserializePropertyValue<GaussianSplatting, String>(ref reader, this, out _kernel); break;
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case "projection": DeserializePropertyValue<GaussianSplatting, String>(ref reader, this, out _projection); break;
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case "sortingMethod": DeserializePropertyValue<GaussianSplatting, String>(ref reader, this, out _sortingMethod); break;
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default: base.DeserializeProperty(jsonPropertyName,ref reader); break;
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}
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}
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#endregion
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}
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}

‎src/SharpGLTF.Core/Schema2/gltf.ExtensionsFactory.cs‎

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RegisterExtension<Node, _NodePunctualLight>("KHR_lights_punctual", p=> new _NodePunctualLight(p));
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RegisterExtension<Node, MeshGpuInstancing>("EXT_mesh_gpu_instancing", p=> new MeshGpuInstancing(p));
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RegisterExtension<Node, _NodeVisibility>(_NodeVisibility.SCHEMANAME, p => new _NodeVisibility(p));
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RegisterExtension<MeshPrimitive, GaussianSplatting>(GaussianSplatting.SCHEMANAME, p => new GaussianSplatting(p));
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RegisterExtension<Material, MaterialUnlit>("KHR_materials_unlit", p => new MaterialUnlit(p));
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RegisterExtension<Material, MaterialSheen>("KHR_materials_sheen", p => new MaterialSheen(p));

‎src/SharpGLTF.Core/Schema2/gltf.MeshPrimitive.GaussianSplatting.cs‎

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using System;
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namespace SharpGLTF.Schema2
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{
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public partial class GaussianSplatting
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{
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#region lifecycle
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internal GaussianSplatting(MeshPrimitive primitive)
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{
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_Owner = primitive;
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}
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#endregion
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#region constants
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public const string KernelEllipse = "ellipse";
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public const string ColorSpaceSrgbRec709Display = "srgb_rec709_display";
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public const string ColorSpaceLinRec709Display = "lin_rec709_display";
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public const string ProjectionPerspective = "perspective";
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public const string SortingMethodCameraDistance = "cameraDistance";
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public const string AttributeRotation = "KHR_gaussian_splatting:ROTATION";
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public const string AttributeScale = "KHR_gaussian_splatting:SCALE";
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public const string AttributeOpacity = "KHR_gaussian_splatting:OPACITY";
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public const string AttributeSHDegree0Coef0 = "KHR_gaussian_splatting:SH_DEGREE_0_COEF_0";
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#endregion
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#region data (not serializable)
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private readonly MeshPrimitive _Owner;
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#endregion
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#region properties
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public MeshPrimitive LogicalParent => _Owner;
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public string Kernel
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{
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get => _kernel;
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set
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{
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Guard.NotNullOrEmpty(value, nameof(value));
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_kernel = value;
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}
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}
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public string ColorSpace
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{
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get => _colorSpace;
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set
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{
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Guard.NotNullOrEmpty(value, nameof(value));
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_colorSpace = value;
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}
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}
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public string Projection
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{
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get => _projection ?? _projectionDefault;
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set
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{
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value = value.AsEmptyNullable();
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_projection = value == _projectionDefault ? null : value;
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}
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}
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public string SortingMethod
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{
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get => _sortingMethod ?? _sortingMethodDefault;
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set
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{
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value = value.AsEmptyNullable();
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_sortingMethod = value == _sortingMethodDefault ? null : value;
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}
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}
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#endregion
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#region API
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public static string GetSphericalHarmonicsAttribute(int degree, int coefficient)
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{
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Guard.MustBeBetweenOrEqualTo(degree, 0, 3, nameof(degree));
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var coefficientCount = 2 * degree + 1;
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Guard.MustBeBetweenOrEqualTo(coefficient, 0, coefficientCount - 1, nameof(coefficient));
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return $"KHR_gaussian_splatting:SH_DEGREE_{degree}_COEF_{coefficient}";
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}
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#endregion
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}
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public sealed partial class MeshPrimitive
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{
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private static readonly string[] _GaussianRequiredAttributes =
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{
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GaussianSplatting.AttributeRotation,
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GaussianSplatting.AttributeScale,
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GaussianSplatting.AttributeOpacity,
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GaussianSplatting.AttributeSHDegree0Coef0
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};
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public GaussianSplatting GetGaussianSplatting()
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{
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return this.GetExtension<GaussianSplatting>();
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}
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public GaussianSplatting UseGaussianSplatting()
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{
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var ext = GetGaussianSplatting();
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if (ext == null)
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{
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ext = new GaussianSplatting(this);
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this.SetExtension(ext);
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}
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return ext;
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}
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public void RemoveGaussianSplatting()
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{
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this.RemoveExtensions<GaussianSplatting>();
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}
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private void _ValidateGaussianSplatting(Validation.ValidationContext validate)
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{
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var gaussian = GetGaussianSplatting();
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if (gaussian == null) return;
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validate.EnumsAreEqual(nameof(DrawPrimitiveType), DrawPrimitiveType, PrimitiveType.POINTS);
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validate.IsDefined("Attributes.POSITION", GetVertexAccessor("POSITION"));
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foreach (var semantic in _GaussianRequiredAttributes)
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{
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validate.IsDefined($"Attributes.{semantic}", GetVertexAccessor(semantic));
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}
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var rotation = GetVertexAccessor(GaussianSplatting.AttributeRotation);
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if (rotation != null)
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{
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validate.IsAnyOf
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(
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$"Attributes.{GaussianSplatting.AttributeRotation}.Format",
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rotation.Format,
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(DimensionType.VEC4, EncodingType.FLOAT),
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(DimensionType.VEC4, EncodingType.BYTE, true),
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(DimensionType.VEC4, EncodingType.SHORT, true)
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);
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}
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var scale = GetVertexAccessor(GaussianSplatting.AttributeScale);
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if (scale != null)
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{
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validate.IsAnyOf
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(
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$"Attributes.{GaussianSplatting.AttributeScale}.Format",
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scale.Format,
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(DimensionType.VEC3, EncodingType.FLOAT),
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(DimensionType.VEC3, EncodingType.BYTE),
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(DimensionType.VEC3, EncodingType.BYTE, true),
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(DimensionType.VEC3, EncodingType.SHORT),
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(DimensionType.VEC3, EncodingType.SHORT, true)
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);
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}
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var opacity = GetVertexAccessor(GaussianSplatting.AttributeOpacity);
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if (opacity != null)
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{
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validate.IsAnyOf
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(
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$"Attributes.{GaussianSplatting.AttributeOpacity}.Format",
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opacity.Format,
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(DimensionType.SCALAR, EncodingType.FLOAT),
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(DimensionType.SCALAR, EncodingType.UNSIGNED_BYTE, true),
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(DimensionType.SCALAR, EncodingType.UNSIGNED_SHORT, true)
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);
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}
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var sh0 = GetVertexAccessor(GaussianSplatting.AttributeSHDegree0Coef0);
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if (sh0 != null)
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{
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validate.IsAnyOf
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(
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$"Attributes.{GaussianSplatting.AttributeSHDegree0Coef0}.Format",
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sh0.Format,
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(DimensionType.VEC3, EncodingType.FLOAT)
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);
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}
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validate.IsTrue(nameof(gaussian.Kernel), !string.IsNullOrWhiteSpace(gaussian.Kernel), "must be defined.");
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validate.IsTrue(nameof(gaussian.ColorSpace), !string.IsNullOrWhiteSpace(gaussian.ColorSpace), "must be defined.");
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}
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}
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}

‎src/SharpGLTF.Core/Schema2/gltf.MeshPrimitive.cs‎

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{
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base.OnValidateContent(validate);
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_ValidateGaussianSplatting(validate);
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// all vertices must have the same vertex count
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int vertexCount = -1;

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