Structure of an STL file

thingiverse

For those interested in the structure of an STL file, I wrote a minimal file with four surfaces. If you look into the file, you will see the general structure of such a file: all triangles. One triangle (facet) is defined by three points (vertex) and the in or out direction of the facet is given by a vector pointing outside. The object itself can be sliced and printed at any size. You can try it without support, 0 infill, and thin walls to test your surface quality. The file: solid OpenSCAD_Model facet normal 0 -1 -3 outer loop vertex 0 10 0 vertex 10 0 0 vertex 0 0 0 endloop endfacet facet normal 1 0 0 outer loop vertex 0 0 10 vertex 0 0 0 vertex 10 0 0 endloop endfacet facet normal -1 0 0 outer loop vertex 0 0 0 vertex 0 10 0 vertex 0 0 10 endloop endfacet facet normal 1 -1 0 outer loop vertex 0 10 0 vertex 0 0 10 vertex 10 0 0 endloop endfacet endsolid OpenSCAD_Model Remark: The "cube" in the name is, in fact, less than one fourth of a cube. Additional files: parts of a cube and a full cube. Some problems when rendering! Note that each face of the cube will be rendered as two triangles. There is also an animation: select 'animate' under 'view' in OpenSCAD. Appropriate values (under the graphic window) are FPS=1 and STEPS=4. =============================================================== Play Split cube: with the customizer, identify the five parts of the cube (red, blue, yellow, green, and grey) Small spheres show the positions. Polyhedron function is used. Feb 17, 2020: added a parm to not show the spheres, so a partial object can be rendered.