Blends on Faces

List of:	Discussion Topic
Subjects:	Blending
Contents:	Advanced Blending

	Transitions onto new entities are only allowed when the spring curve of the blend leaves the face, having been inside it. Therefore, transitions are not supported at places at which the face boundary is merely grazed, either from the inside or outside. In some cases, an edge or vertex exists in a face only to support modeling functions, although it does not really need to be there in the pure boundary representation. This includes an edge in a periodic face that exists only to break the periodicity, such as the edge that splits the periodic face in a cylinder from one end cap to the other. In such a case, the edge is embedded in the face; i.e., the same face exists on both sides of the edge. Transitions onto new entities are not supported at such edges or vertices.
	Table 1-3. Blends on Faces

Run Into	Transition	How to Obtain
smooth edge	roll onto next face	place rollon on face (default)
smooth edge	start capping	place cap on face
sharp edge	start capping	place cap on edge (default)
sharp edge	roll onto edge	place rollon on edge
smooth vertex	roll onto smooth face	place rollon on face (default)
smooth vertex	start capping	place cap on face
sharp vertex	start capping	place cap on vertex (default)

	A smooth vertex is a vertex at which there is a smoothly joined face into which the blend will definitely be able to travel. This excludes vertices at which there is a smooth face and the direction of travel of the blend lies along one of that face's boundaries at the vertex.
	A sharp vertex is a vertex at which there is definitely no smoothly connected face, or if there is, the direction of travel of the blend definitely excludes it from going into this face. This excludes vertices at which there is a smooth face and the direction of travel of the blend lies along one of that face's boundaries at the vertex.
	Any blend leaving the face at a vertex where there is a smoothly connected face, but the direction of travel of the blend lies along one of that face's boundaries at that vertex, is not currently supported.

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