Try this code which I believe was originally by Sswift which I put a wrapper on.
My understanding (though I could be wrong) is that it removes shared vertices and gives each surface it's own.
;-------------------------------------------------------------------------------------------------------------------
; This function calculates and sets the normals for a mesh.
; Should probably update this so that it can recursively loop through all of an entities children as well.
;-------------------------------------------------------------------------------------------------------------------
Const swiftmax = 65535 ;32768
Const maxtris = 32*4
Dim Face_NX#(swiftmax)
Dim Face_NY#(swiftmax)
Dim Face_NZ#(swiftmax)
Dim Vertex_ConnectedTris(swiftmax)
Dim Vertex_TriList(swiftmax, maxtris)
;----------------------
Function JSmooth(model)
;----------------------
cc = CountChildren(model)
If cc > 0
For c = 1 To cc
child = GetChild(model,c)
If EntityClass$(child)="Mesh"
Calculate_Normals(child)
EndIf
Next
Else
If EntityClass$(model)="Mesh"
Calculate_Normals(model)
EndIf
EndIf
End Function
;----------------------
Function Calculate_Normals(ThisMesh)
;----------------------
; Stop
; Loop through all surfaces of the mesh.
Surfaces = CountSurfaces(ThisMesh)
For LOOP_Surface = 1 To Surfaces
Surface_Handle = GetSurface(ThisMesh, LOOP_Surface)
; Reset the number of connected polygons for each vertex.
For LoopV = 0 To 32767
Vertex_ConnectedTris(LoopV) = 0
Next
; Loop through all triangles in this surface of the mesh.
Tris = CountTriangles(Surface_Handle)
For LOOP_Tris = 0 To Tris-1
; Get the vertices that make up this triangle.
Vertex_0 = TriangleVertex(Surface_Handle, LOOP_Tris, 0)
Vertex_1 = TriangleVertex(Surface_Handle, LOOP_Tris, 1)
Vertex_2 = TriangleVertex(Surface_Handle, LOOP_Tris, 2)
; Adjust the number of triangles each vertex is connected to and
; store this triangle in each vertex's list of triangles it is connected to.
ConnectedTris = Vertex_ConnectedTris(Vertex_0)
Vertex_TriList(Vertex_0, ConnectedTris) = LOOP_Tris
Vertex_ConnectedTris(Vertex_0) = ConnectedTris + 1
ConnectedTris = Vertex_ConnectedTris(Vertex_1)
Vertex_TriList(Vertex_1, ConnectedTris) = LOOP_Tris
Vertex_ConnectedTris(Vertex_1) = ConnectedTris + 1
ConnectedTris = Vertex_ConnectedTris(Vertex_2)
Vertex_TriList(Vertex_2, ConnectedTris) = LOOP_Tris
Vertex_ConnectedTris(Vertex_2) = ConnectedTris + 1
; Calculate the normal for this face.
; Get the corners of this face:
Ax# = VertexX#(Surface_Handle, Vertex_0)
Ay# = VertexY#(Surface_Handle, Vertex_0)
Az# = VertexZ#(Surface_Handle, Vertex_0)
Bx# = VertexX#(Surface_Handle, Vertex_1)
By# = VertexY#(Surface_Handle, Vertex_1)
Bz# = VertexZ#(Surface_Handle, Vertex_1)
Cx# = VertexX#(Surface_Handle, Vertex_2)
Cy# = VertexY#(Surface_Handle, Vertex_2)
Cz# = VertexZ#(Surface_Handle, Vertex_2)
; Triangle 1
; Get the vectors for two edges of the triangle.
Px# = Ax#-Bx#
Py# = Ay#-By#
Pz# = Az#-Bz#
Qx# = Bx#-Cx#
Qy# = By#-Cy#
Qz# = Bz#-Cz#
; Compute their cross product.
Nx# = Py#*Qz# - Pz#*Qy#
Ny# = Pz#*Qx# - Px#*Qz#
Nz# = Px#*Qy# - Py#*Qx#
; Store the face normal.
Face_NX#(LOOP_Tris) = Nx#
Face_NY#(LOOP_Tris) = Ny#
Face_NZ#(LOOP_Tris) = Nz#
Next
; Now that all the face normals for this surface have been calculated, calculate the vertex normals.
Vertices = CountVertices(Surface_Handle)
For LOOP_Vertices = 0 To Vertices-1
; Reset this normal.
Nx# = 0
Ny# = 0
Nz# = 0
; Add the normals of all polygons which are connected to this vertex.
Polys = Vertex_ConnectedTris(LOOP_Vertices)
For LOOP_Polys = 0 To Polys-1
ThisPoly = Vertex_TriList(LOOP_Vertices, LOOP_Polys)
Nx# = Nx# + Face_NX#(ThisPoly)
Ny# = Ny# + Face_NY#(ThisPoly)
Nz# = Nz# + Face_NZ#(ThisPoly)
Next
; Normalize the new vertex normal.
; (Normalizing is scaling the vertex normal down so that it's length = 1)
Nl# = Sqr(Nx#^2 + Ny#^2 + Nz#^2)
; Avoid a divide by zero error if by some freak accident, the vectors add up to 0.
; If Nl# = 0 Then Nl# = 0.1
Nx# = Nx# / Nl#
Ny# = Ny# / Nl#
Nz# = Nz# / Nl#
; Set the vertex normal.
VertexNormal Surface_Handle, LOOP_Vertices, Nx#, Ny#, Nz#
;VertexColor Surface_Handle, LOOP_Vertices, polys*127, polys*127, polys*127
Next
Next
End Function
==> 
:)