cgal_buffer_multi_point

Geometric functions > cgal_buffer_multi_point

syntax

• cgal_buffer_multi_point(multipoint_data_item, size, nr_angles)

description

cgal_buffer_multi_point(multipoint_data_item, size, nr_angles) results in a multi polygon data item with buffer circles around each coordinate in the multipoint_data_item. The resulting data item has the same domain unit as the multipoint_data_item.

The size argument indicates the buffer circle size (radius) in the units of the coordinate system.

The nr_angles argument indicates how many angles are used to make the buffer circles. More angles result in smoother circles but also in more data.

The cgal_ prefix of the function name indicates that the implementation of the operator uses CGAL, which provides exact predicates and exact constructions for maximum numerical precision.

applies to

• attribute multipoint_data_item with a point value type and multipoint composition type
• data item size with a Float64 value type
• data item nr_angles with a UInt8 value type

changed restriction

Since version 20.2.0 the first argument is expected to have multipoint composition type. Passing an arc or polygon attribute is deprecated: it still works but produces a deprecation warning, and is slated to become an error in a future major version. Construct genuine multipoint geometry with points2multi_point. Before 20.2.0 this operator accepted arc or polygon geometry (their coordinates were treated as a set of points).

conditions

1. size must be a positive value.
2. nr_angles must be at least 3.

since version

14.0

example

attribute<dpoint> points         (district, multipoint) := points2multi_point(point, Sequence_rel, ordinal);
attribute<dpoint> buffer_circles (district, polygon)    := cgal_buffer_multi_point(points, 10.0, 16b);

More examples of buffer functions can be found here: Buffer processing example

see also

• cgal_buffer_point
• cgal_buffer_linestring
• geos_buffer_multi_point
• bg_buffer_multi_point
• bp_buffer_multi_point
• points2multi_point - construct multipoint geometry