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Suppose that you have a face, called
face, and you want to produce a pattern of elements, from the seed entity
ent, that follow the face's surface both in terms of position and direction. The function
api_surface_pattern can be used with either a surface or a face.
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You must specify the point, named
root in this example, to be mapped to the pattern sites on the face. This may be a point on the seed entity, if you want the seed entity to intersect the face, but it need not be. You may simply wish to create a pattern that is parallel to the face, at some distance, in which case you can specify a point removed from the seed entity. Similarly, you need to specify the directions to be mapped to the two orthogonal tangent directions of the surface. For example, call these
u_dir and
v_dir, since they correspond to the
uv parameterization of the face's surface. You may then proceed as follows:
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// define the pattern parameters
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pattern* pat = NULL;
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int num_u = . . .;
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int num_v = . . .;
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SPAposition root(. . ., . . ., . . .);
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logical on_boundary = . . .;
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SPAvector u_dir(. . ., . . ., . . .);
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SPAvector v_dir(. . ., . . ., . . .);
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// create the pattern
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outcome result = api_surface_pattern(pat, face, num_u,
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num_v, root, on_boundary, u_dir, v_dir);
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check_outcome(result);
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// apply the pattern
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result = api_set_entity_pattern(ent, pat);
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check_outcome(result);
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// clean up
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pat->remove();
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