## 3D Shapes

The shapes that Moritz can polygonalize are shown on this page. Each shape is shown as a solid and a wireframe. Hidden surfaces are not removed in the wireframe view.

Right Parallelepiped-RPP:A shape bounded by 3 pairs of parallel planes, each of which is perpendicular to a coordinate axis.

Polyhedron-PHEDRON:A Shape bounded by up to 20 plane surfaces. If the Use RPPs box on the 3D Options property page is not checked, a part that qualifies for an RPP shape will be polygonalized as a PHEDRON.

Sphere-SPH:A shape inside a spherical surface.

Ellipsoid-ELL:A shape inside an ellipsoid surface.

Right Circular Cylinder-RCC:A shape inside a circular cylinder or between two circular cylinders parallel to the same axis and between two planes perpendicular to the cylinder axis. The inner cylinder must lie completely inside the outer cylinder. If the cylinders intersect, the shape is usually successfully polygonalized as a TRIPOLY or general cylinder.

Cylindrical Mesh Element-CYL CELL:The CYL shape was introduced for the display of cylindrical meshes, but can be used for ordinary cells as well. The shape lies between two concentric cylinders perpendicular to top and bottom planes with side planes intersecting at the cylinders' center.

Truncated Right Cone-TRC:A shape inside a circular cone or between two circular cones parallel to the same axis and between two planes perpendicular to the cone axis. The inner cone must lie completely inside the outer cone. The polygon representation will be incorrect if a cone origin lies between the bound planes; Moritz does not yet check for this case.

Right Elliptical Cylinder-ERCC:A shape inside an elliptical cylinder or between two elliptical cylinders parallel to the same axis and between two planes perpendicular to the cylinder axis. The inner cylinder must lie completely inside the outer cylinder. In the case of two cylinders, one may be circular. If the cylinders intersect, the shape is usually successfully polygonalized as a general cylinder.

Shell-SHELL:A shape between two spheres, between two ellipsoids, or between a sphere and an ellipsoid. The inner surface must be contained completely within the outer surface. In the solid representation, a cutter plane is used to expose the inner surface.

Flattened Ellipsoid-FLAT ELL:A shape inside a sphere or ellipsoid and bounded by up to six PX, PY, or PZ planes, but by not more than 2 planes of the same type. In most cases a TRIPOLY is used instead of the FLAT ELL.

Flattened Shell-FSHELL:A shape between two spheres, between two ellipsoids, or between a sphere and an ellipsoid and one or two planes. The inner surface must be contained completely within the outer surface. If two planes are present, they must be parallel.

Torus-TOR:A shape inside a torus surface.

Partial Torus-TOR:A shape inside a torus surface or between two concentric tori and on one side of one or two planes that are parallel to the torus axis and pass through or near the center of the torus.

Surface of Revolution-REV:A shape bounded by surfaces that are symmetric about the same axis. The surfaces can be planes, spheres, right ellipsoids, cylinders, cones, and tori. Special quadratic (SQ) surfaces will be added. The axis must be one of the Cartesian coordinate axes (X, Y, or Z).

We have encountered additional problems with the REV shape including incorrect surface normals, spurious errors when geometry checking, and problems clip planes in the solid clip mode. Shapes that can be rendered as REV can also be polygonalized with the combinatorial triangles method with a small computation time penalty. The No REV item on the 3D Advanced Options property page bypasses the use of the surface of revolution (REV) shape when polygonalizing cells. The default is to not use the REV shape.

General Cylinder-PCYL:A shape bounded by at least one cylindrical or conical surface and two planes perpendicular to the axis of the cylinder or cone and that cannot be classified as one of the above shapes.

Cominatorial Triangles Polygonalization-TRIPOLY:A shape constructed from a combinatorial algorithm based on triangular polygonalization of 2 or more shapes that cannot be classified as one of the above shapes. The solid shown above is a torus and a sphere subtracted from an ellipsoid. The algorithm is discussed in more detail below.

The General Ellipsoid (PELL) shape used in previous versions has been retired in favor of the TRIPOLY shape.

We will add additional shapes in the future

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