Importing Geometry (DXF/STL/OBJ)

You can draw chute faces directly in HelixChute2 by adding Layers, or draw them in a CAD or 3D modelling program (AutoCAD®, SolidWorks®, MicroStation®, or any tool that can export one of the supported formats) and import them using File > Import Geometry....

HelixChute2 imports three formats:

Format	Extension	Notes
DXF	`.dxf`	Reads `3DFACE` entities, one per layer/colour group. Lines, polylines and solids are ignored.
STL	`.stl`	Reads triangulated facets. If the file uses named `solid` blocks (ASCII STL), each named solid becomes its own layer.
OBJ	`.obj`	Reads polygon faces (quads are kept as 4-vertex faces, not triangulated); named groups/objects become layers.

Preparing your drawing

Faces must be genuine 3D face/polygon entities (e.g. DXF 3DFACE) – plain lines, polylines or solids are not imported.
Group related faces onto the same layer/name in your drawing program (e.g. all belt faces on a layer called "Belt", the rock box on "Rockbox", etc.) – each becomes a separate Layer in HelixChute2's Layers table, so you can then manipulate it as a unit (colour, friction, restitution, or move it).
Represent curved surfaces as a series of flat faces (a "lobster back") – the program needs a genuine plane to calculate a normal vector for particle reflection.
Do not leave gaps between chute faces – the DEM calculation will "leak" particles through any gap.
Draw in metres. If your drawing is in millimetres, scale it by 0.001 before exporting.
Keep the drawing near the origin (0,0,0) – geometry far from the origin may import correctly but be out of the visible drawing range.

To import a drawing

Open a new or existing project.
Select File > Import Geometry....
Choose the file (DXF, STL or OBJ) and press Open.
HelixChute2 adds the imported faces to the Layers, Faces and Vertices tables. Press Draw to see them.
Adjust the settings for each new layer – restitution, friction, colour, and (for moving faces such as a conveyor belt) the Vx, Vy, Vz velocity components. See Add/Edit Layers, Faces, Vertices.
Some drawing programs (notably AutoCAD) add redundant duplicate vertices when creating a 3D face. Right-click the Layers table and use Round off Vertices then Remove Duplicate Vertices to clean these up.

An OBJ that imports as dozens of one-face layers. Because named groups/objects become layers, a model built from many small meshes arrives as a long list of layers holding a single face each. Select them in the Layers table and use Merge Selected Layers... to combine them into one layer you can set friction, e and colour on in a single step.

A detailed sample chute is supplied in all three formats under samples\Geometry (Demo Chute.dxf, Demo Chute.stl, Demo Chute.obj) so you can compare how each format represents the same geometry.

Example CAD drawing with a curved surface built from 3D faces — A curved surface built from a series of flat 3D faces in a CAD drawing.

See also: Exporting Geometry, Merge Layers, Add/Edit Layers, Faces, Vertices, FAQ (duplicate vertices, non-planar faces).