Hey developers! We can modify existing mesh vertices in an unsafe way: Point3d[] pointsArray = new Point3d[countX * countY]; unsafe { using (var meshAccess = mesh.GetUnsafeLock(true)) { Point3d* startOfVertexArray = meshAccess.VertexPoint3dArray(out int arrayLength); Parall…

[image] Mariusz Hermansdorfer: mesh MeshVertexList has settable Capacity and Count properties. Make sure you understand if you want to set the 3F or the 3D array. I’d go with setting 3D. Also, I suggest you time this. With unmanaged access, I doubt that this version of Parallel.For does much …

Would it maybe work if you set the MeshVertexList.Capacity first, then perform the unsafe operation? Also, what happens when the point3d array gets garbage collected, or moved by the garbage collector? You may want to use a GCHandle to prevent the GC from pulling the rug from under your mesh. Edit…

Setting the correct Count value was the missing bit. Thanks @piac ! For whatever reason I can’t access the 3D array: Rhino.Geometry.Mesh mesh = new Rhino.Geometry.Mesh(); mesh.Vertices.UseDoublePrecisionVertices = true; mesh.Vertices.Capacity = countX * countY; …

@mrhe sorry I’m AFK, but I think you have to have at least one vertex before switching.

Yep, adding a dummy Point3d does the job. mesh.Vertices.UseDoublePrecisionVertices = true; doesn’t seem to do anything. With unmanaged access, I doubt that this version of Parallel.For does much difference, or even, good You were right, for approx. 1M verts, Parallel.For doesn’t come with a meas…

[image] Mariusz Hermansdorfer: I am trying to squeeze out maximum performance here and understand the risks involved. Since the thread is specifically tagged windows and you’re willing to do things marked unsafe, if you’re working with 1M+ vertex meshes and really need performance, is there a…

Good point @Nathan_Bossett ! I tested it with the faces array - since the input data was already correctly laid out - and it runs at the same speed: MeshFace* startOfFacesArray = meshAccess.FacesArray(out int facesArrayLength); fixed (int* ptr = faces) …

@piac , is there a reason why the VertexColorsArray is not exposed in unmanaged access? We can modify vertices, vertex normals, and faces but not colors.

[image] Mariusz Hermansdorfer: is there a reason why the VertexColorsArray is not exposed in unmanaged access? Is “Nobody asked” a good excuse? I’ve added a wish at RH-77392 . Also face normals, surface coordinates could probably get the same treatment.

Thanks @piac ! That was fast :slight_smile:

Create Mesh Vertices/Faces via unsafe access

Rhino Developer

piac (Giulio Piacentino) October 4, 2023, 8:49am 11

@mrhe, the next release of Rhino 8 BETA will contain a function to access VertexColorsArray and FaceNormals.

Thanks,

Giulio

–
Giulio Piacentino
for Robert McNeel & Associates
giulio@mcneel.com

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Create Mesh Vertices/Faces via unsafe access

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