[Question] How to Apply 3d transformations on 3d Mesh vertcies about helix-toolkit

[holance]

You need to recalculate normals/tangents/bi-tangents after non uniform scaling on all vertices.
You can use MeshGeometry3D.Normals= MeshGeometry3D.CalculateNormals().

[softinitializing]

Yeah i get that ,but i was thinking of using the principles/code that the toolkit use yo handels Transformations , without recalculating normals ,if that possible ?

[holance]

Since you already apply transform onto vertices, you will need to update normals as long as its non uniform scaling. You need to multiply inverse transposed model matrix onto normal vectors to correctly update the normal values.