AssimpContext.ExportFile broken

[Xeeynamo]

Using ExportFile method always results to a crash, regardless the format I am exporting to:
using var ctx = new AssimpContext(); ctx.ExportFile(new Scene(), fileName, "obj");

Exception:
System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

I am using .Net Core 3.1 and AssimpNet 4.1.0.

[kenjiuno]

Hi.
It seems that we need at least RootNode:

Scene scene = new Scene();
scene.RootNode = new Node("Root");

using var ctx = new AssimpContext();
ctx.ExportFile(scene, fileName, "obj");

I have found test case that it creats scene from scratch.

assimp-net/AssimpNet.Test/AssimpContextTestFixture.cs

Lines 75 to 101 in ed18dda

	[Test]
	public void TestExportToFile()
	{
	String path = Path.Combine(TestHelper.RootPath, "TestFiles\\ExportedTriangle.obj");
	//Create a very simple scene a single node with a mesh that has a single face, a triangle and a default material
	Scene scene = new Scene();
	scene.RootNode = new Node("Root");
	Mesh triangle = new Mesh("", PrimitiveType.Triangle);
	triangle.Vertices.Add(new Vector3D(1, 0, 0));
	triangle.Vertices.Add(new Vector3D(5, 5, 0));
	triangle.Vertices.Add(new Vector3D(10, 0, 0));
	triangle.Faces.Add(new Face(new int[] { 0, 1, 2 }));
	triangle.MaterialIndex = 0;
	scene.Meshes.Add(triangle);
	scene.RootNode.MeshIndices.Add(0);
	Material mat = new Material();
	mat.Name = "MyMaterial";
	scene.Materials.Add(mat);
	//Export the scene then read it in and compare!
	AssimpContext context = new AssimpContext();
	Assert.IsTrue(context.ExportFile(scene, path, "obj"));

[Xeeynamo]

Thank you @kenjiuno , that was definitively the case.

Although it would be very good if this library was throwing a proper exception message for it (eg. ArgumentException rather than AccessViolationException). I am not going to close this issue, unless the maintainer of this repo would think that argument validation is not required.

[Starnick]

Access violation could be the native lib just assumes it exists. More validation and error messages are always welcomed.

This repo isn't the official assimpnet one, and is very old compared to the last few nuget releases. I'm on bit bucket. Several times now I've requested transfer of ownership or admin of this github repo without any action.

Feel free to do a PR for extra validation here https://bitbucket.org/Starnick/assimpnet/src