pytha.create_part_from_mesh

Creates a part in PYTHA from a triangle mesh.

Builds a single part from a shared list of vertices and a list of triangular faces that index into it. This is the in-memory equivalent of importing a triangle mesh (e.g. an STL file).

Note: Only triangular faces are supported, and the faces may not contain holes or arcs. For a single flat face with holes or arcs, use create_polygon_ex instead.

pytha.create_part_from_mesh(points, faces [,origin [,options]])

Parameter	Type	Description
points	{{x,y,z}, ...}	Shared vertex pool. Faces reference these vertices by 1-based index.
faces	{{i1,i2,i3}, ...}	Triangles, each a triple of indices into points. Each index must be in [1..#points]. Triangles in which two indices are equal are silently discarded.
origin	{x,y,z}	Optional: offset of the whole mesh
options	{...}	Optional: a table that may contain the following options:
options.u_axis	{x,y,z}	Local coordinate u-axis for the orientation of the mesh
options.v_axis	{x,y,z}	Local coordinate v-axis for the orientation of the mesh
options.w_axis	{x,y,z}	Local coordinate w-axis for the orientation of the mesh
options.melt_points	boolean	false (default), true; welds geometrically coincident vertices that were supplied with separate indices (repairs open seams in a triangle soup)
options.melt_faces	boolean	false (default), true; merges adjacent coplanar faces into larger faces (the result is then no longer a pure triangle mesh)

Return value

Type	Description
element_handle	An element handle of the newly created part

Winding convention

Each triangle must be wound counter-clockwise (CCW) as seen from outside the solid, i.e. its vertices appear in CCW order when looking at the face against its outward-pointing normal (right-hand rule). For an internal surface (a bore or a socket) "outside" is the empty space, so its CCW winding makes the normal point into the cavity, away from the material. Wind every face consistently to this rule — a mix of CCW and CW faces yields inverted (back-facing) surfaces.

Notes:

• Indices are 1-based, consistent with the rest of the API and with points[i].
• Vertices shared between triangles via the same index are shared in the resulting part automatically; coincident vertices supplied with different indices are only welded when melt_points is enabled.
• Both closed solids and open shells are supported.

Example:

A cube (8 vertices, 12 triangles):

local cube = pytha.create_part_from_mesh(
    {
        {0, 0, 0}, {10, 0, 0}, {10, 10, 0}, {0, 10, 0},   -- bottom
        {0, 0, 10}, {10, 0, 10}, {10, 10, 10}, {0, 10, 10}, -- top
    },
    {
        {1, 3, 2}, {1, 4, 3},   -- bottom
        {5, 6, 7}, {5, 7, 8},   -- top
        {1, 2, 6}, {1, 6, 5},   -- front
        {2, 3, 7}, {2, 7, 6},   -- right
        {3, 4, 8}, {3, 8, 7},   -- back
        {4, 1, 5}, {4, 5, 8},   -- left
    }
)

A soup whose seam vertices are duplicated, welded into a single watertight part:

local part = pytha.create_part_from_mesh(points, faces, {0, 0, 0}, { melt_points = true })

Version Support:

Minimum PYTHA Version: V27

See also:

pytha, element handles, Axes and directions, create_polygon_ex, import_pyo