Code/HumanoidRetargeter/Core/Formats/Gltf/GltfModelDmxWriter.Compact.cs
A helper that compacts a MeshPart by removing unused vertex data. It builds a list of distinct triangle vertex indices, remaps vertex attributes (positions, normals, texcoords, skin weights/joints, and morph targets) to the smaller vertex buffer, and updates triangle indices accordingly.
Reflection
using System.Linq;
namespace HumanoidRetargeter.Core.Formats.Gltf;
public static partial class GltfModelDmxWriter
{
private static MeshPart Compact( MeshPart part )
{
// MMD materials share one vertex buffer. Export only the vertices each uses.
var indices = part.Triangles.Distinct().OrderBy( index => index ).ToArray();
if ( indices.Length == part.Positions.Length )
return part;
var remap = new int[ part.Positions.Length ];
for ( var i = 0; i < indices.Length; i++ )
remap[ indices[ i ] ] = i;
part.Positions = indices.Select( index => part.Positions[ index ] ).ToArray();
part.Normals = indices.Select( index => part.Normals[ index ] ).ToArray();
part.TexCoords = indices.Select( index => part.TexCoords[ index ] ).ToArray();
part.Weights = indices.SelectMany( index => part.Weights.Skip( index * 4 ).Take( 4 ) ).ToArray();
part.Joints = indices.SelectMany( index => part.Joints.Skip( index * 4 ).Take( 4 ) ).ToArray();
part.Triangles = part.Triangles.Select( index => remap[ index ] ).ToArray();
foreach ( var name in part.Morphs.Keys.ToArray() )
part.Morphs[ name ] = indices.Select( index => part.Morphs[ name ][ index ] ).ToArray();
return part;
}
}