domcr / meshio

3D library in pure C# that allows reading and writing in multiple formats.

MeshIO

C# modular library to read/write and modify different 3D formats.

Here you can find a sample project that shows how to use MeshIO.

MeshIO modules

Each module integrates a different 3D format, all of them use MeshIO as a core library so it makes easier to modify and convert the different 3D formats.

MeshIO.FBX

• Read FBX binary files
• Read/Write FBX ASCII files
• Process and add custom FbxProperties

For more information.

MeshIO.STL

• Read/Write STL binary files
• Read/Write STL ASCII files

For more information.

MeshIO.GLTF

• Read GLB files

For more information.

MeshIO.OBJ

• Read Wavefront OBJ files

For more information.

Contributing

Please feel free to fork this repo and send a pull request if you want to contribute to this project.

meshio's Issues

Can't export to FBX

Hello.
I was trying to export my mesh to fbx with this code:
(Mesh was constructed from Unity model and I was able to successfully export it to STL earlier)

        MeshIO.Scene scene = new();
        scene.RootNode.Nodes.Add(convertedMesh);
        string pathfBX = System.IO.Path.Combine("D:/test", "fbx_bin.fbx");
        using(MeshIO.FBX.FbxWriter writer = new MeshIO.FBX.FbxWriter(pathfBX, scene)) {
            writer.Write(MeshIO.FBX.FbxFileFormat.Binary);
        }

This generates exception:

InvalidOperationException: Nullable object must have a value.
System.Nullable`1[T].get_Value () (at <88e4733ac7bc4ae1b496735e6b83bbd3>:0)
MeshIO.FBX.Converters.SceneConverterBase.buildObjectsNode () (at MeshIO.FBX/Converters/SceneConverterBase.cs:171)
MeshIO.FBX.Converters.SceneConverterBase.ToRootNode () (at MeshIO.FBX/Converters/SceneConverterBase.cs:82)
MeshIO.FBX.FbxRootNode.CreateFromScene (MeshIO.Scene scene, MeshIO.FBX.FbxVersion version) (at MeshIO.FBX/FbxRootNode.cs:28)
MeshIO.FBX.FbxWriter.Write (MeshIO.FBX.FbxFileFormat fileFormat) (at MeshIO.FBX/FbxWriter.cs:104)

If I try to add some ID like this:

        convertedMesh.Id = 0;

then exception changes to this:

FbxException: Invalid property type System.UInt64, at Geometry/Objects[0]
MeshIO.FBX.FbxBinaryWriter.WriteProperty (System.Object obj, System.Int32 id) (at MeshIO.FBX/Writers/FbxBinaryWriter.cs:195)
MeshIO.FBX.FbxBinaryWriter.WriteNode (MeshIO.FBX.FbxRootNode document, MeshIO.FBX.FbxNode node) (at MeshIO.FBX/Writers/FbxBinaryWriter.cs:254)
MeshIO.FBX.FbxBinaryWriter.WriteNode (MeshIO.FBX.FbxRootNode document, MeshIO.FBX.FbxNode node) (at MeshIO.FBX/Writers/FbxBinaryWriter.cs:271)
MeshIO.FBX.FbxBinaryWriter.Write () (at MeshIO.FBX/Writers/FbxBinaryWriter.cs:60)
MeshIO.FBX.FbxWriter.Write (MeshIO.FBX.FbxFileFormat fileFormat) (at MeshIO.FBX/FbxWriter.cs:109)

If I change to ACSII, then I get some file, which apps can not open:
fbx_ascii.zip

Unfortunately I was not able to find examples of saving FBX with this library. Even MeshIO.STL.Tests just creates empty scene without trying to save actual model. So I'm not sure if I did something wrong, or support for fbx format is incomplete.

Nuget Package

Hi! This is awesome what you're doing here. I was thinking about maybe using your MeshIO.FBX in my AssetRipper project. Would you be willing to publish a nuget package for it?

Materials

Implementation for shading materials

Force dot instead of comma for decimal number separator in ASCII formats.

When I was trying to use this library from Unity I noticed that exported ASCII STL files looked incorrectly.
For example vertex looks like that:
vertex 3,488124 8,464913 11
So the result was corrupted:

To fix this problem I changed StlWriter as described here https://groups.google.com/g/dotnetdevelopment/c/weQuHv-C-XE

		public void WriteAscii(Mesh mesh)
		{
			this.validate(mesh);
			
			using (TextWriter tw = new StreamWriter(this._stream.Stream, new UTF8Encoding(false)))
			{
				System.Globalization.NumberFormatInfo nfi = new();
				nfi.NumberDecimalSeparator = ".";

				tw.WriteLine($"solid {mesh.Name}");

				LayerElementNormal normals = mesh.Layers.GetLayer<LayerElementNormal>();
				for (int i = 0; i < mesh.Polygons.Count; i++)
				{
					XYZ normal = normals.Normals[i];

					tw.WriteLine($"  facet normal {normal.X.ToString(nfi)} {normal.Y.ToString(nfi)} {normal.Z.ToString(nfi)}");

					tw.WriteLine($"    outer loop");

					foreach (int item in (Triangle)mesh.Polygons[i])
					{
						var v = mesh.Vertices[item];

						tw.WriteLine($"      vertex {v.X.ToString(nfi)} {v.Y.ToString(nfi)} {v.Z.ToString(nfi)}");
					}

					tw.WriteLine($"    endloop");
					tw.WriteLine($"  endfacet");
				}

				tw.WriteLine($"endsolid {mesh.Name}");
			}
		}

With this changes result looks as intended

I'm not sure that this is the best solution, so I decided to create an issue here.

Extract vertices data (X,Y,Z) from a *.fbx

Hi. How can I extract vertices data (X,Y,Z list) from a *.fbx 3D model via MeshIO?
For example, suppose I have a box in the fbx file (attached) and I want to extract the coordinates of its vertices in CSV format. What should I do?
box1.zip

Open to pull requests?

I want to help development here. Are you open to pull requests? If not, I can just fork and continue on my own development path.

How to write a FLAC3D file?

Hello~It is amazing to find this tool, but I can not figure out how to write a FEM file out to specific file, say FLAC3D?