Developer's Desktop: 5 Essential Functions of 3D ACIS Modeler
By Brian Tomas, ACIS 3D Modeling Development Director
If you were asked, “What is a geometry kernel used for?”, you would probably respond: “To create 3D models.” Most applications enabled by 3D ACIS Modeler create 3D models. If you have read this far, you have probably created a 3D model at some point in your life. The basic steps have not changed a lot in the last 25 years.
Sketching is the process used to create a collection of curves, circles, ellipses, lines, and B-splines. Sketching is just connecting the dots, users input points and tangents, then applying constraints on a 2D grid. The collection of curves matches part of a design, or makes one up.
Curves can create surfaces by extruding, revolving, sweeping, or skinning. Surfaces can be trimmed and stitched to create solids.
The construction of primitive solids follows from specific parameters. This may include solids such as spheres, tori, cuboids, etc.
Finally, overlapping simple solids can be combined with Boolean operations like union and subtract to make a complex 3D model. In 3D ACIS Modeler, 3D models can also be non-manifold, combining solids, two sided sheet bodies and wires.
While all of the above is standard fare for a geometry kernel, creating stable, fast, high-level APIs for a geometry kernel is no small feat. One of the training exercises at Spatial for new 3D ACIS Modeler developers is writing a function to create a solid tetrahedron using low-level interfaces. It’s surprisingly hard - try for yourself.