The AutoCAD Writer has the following limitations when writing hatch features: Hatch features must be closed area features of polygon, donut, or aggregate geometry according to how the AutoCAD Reader created them.
The AutoCAD Reader has the following limitations when reading hatch features: Associative hatches are not preserved, one pattern is allowed per hatch, only one or two color gradients are supported, unclosed hatch boundary loops are closed, and splines are not supported for hatch boundary loops. The AutoCAD reader will also preserve polyline bulge information. Features created may be of polygon, donut, or aggregate geometry, where the aggregates may contain either donuts and polygons or just ordered polygons depending on the usage of the Preserve Complex Hatches and MPolygons reader parameter. The AutoCAD Reader creates features with varied geometry depending on the geometry of the loops that compose them. (Since loops are closed lines that are considered area boundaries, they are essentially polygons.)
The loops of each hatch are closed, simple, continuous, and are not self-intersecting except at their endpoints. They are composed of two-dimensional boundary loops that define areas which can be filled with line patterns or color gradients. Hatch features represent AutoCAD hatch entities.
