判断实体边的凸凹性

convex

PK_EDGE_convexity_convex_c

concave

PK_EDGE_convexity_concave_c

variable
the convexity varies along the edge

PK_EDGE_convexity_variable_c

smooth flat
parallel surface normals, both faces have zero face curvature

PK_EDGE_convexity_smooth_flat_c

smooth convex
edge convexity is smooth, both faces have positive curvature (or one has zero, one has positive)

PK_EDGE_convexity_smooth_cvx_c

smooth concave
edge convexity is smooth, both faces have negative curvature (or one has zero, one has negative)

PK_EDGE_convexity_smooth_ccv_c

smooth inflection
edge convexity is smooth, faces have opposite curvature

PK_EDGE_convexity_smooth_inf_c

smooth variable

edge convexity is smooth, some parts are smooth convex, some parts are smooth concave

PK_EDGE_convexity_smooth_var_c

knife convex
surface normals are anti-parallel and the sum of the curvatures is non-negative

PK_EDGE_convexity_knife_cvx_c

knife concave
surface normals are anti-parallel and the sum of the curvatures is non-positive

PK_EDGE_convexity_knife_ccv_c