A 3D CAD application usually contains several layers that solve very different problems. The user interface manages commands and interaction, the document model stores engineering intent, visualization turns model data into something that can be displayed, and import or export components communicate with external formats. Between these systems sits the geometry layer: the part responsible for representing precise shape and performing the calculations that actually modify a model.
What Belongs in the Geometry Layer?
At its lowest level, the geometry layer works with mathematical entities.
Points and vectors define positions and directions. Curves can represent lines, circles, ellipses, or spline-based shapes. Surfaces describe planes, cylinders, cones, tori, and freeform geometry.
These entities support calculations such as evaluation, projection, transformation, distance measurement, and intersection.
