CGAL 5.4 - 2D and 3D Linear Geometry Kernel
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#include <CGAL/Filtered_predicate.h>
Filtered_predicate
is an adaptor for predicate function objects that allows one to produce efficient and exact predicates.
It is used to build CGAL::Filtered_kernel<CK>
and can be used for other predicates too.
EP
is the exact but supposedly slow predicate that is able to evaluate the predicate correctly. It will be called only when the filtering predicate, FP
, cannot compute the correct result. This failure of FP
must be done by throwing an exception.
To convert the geometric objects that are the arguments of the predicate, we use the function objects C2E
and C2F
, which must be of the form Cartesian_converter
or Homogeneous_converter
.
Example
The following example defines an efficient and exact version of the orientation predicate over three points using the Cartesian representation with double coordinates and without reference counting (Simple_cartesian::Point_2
). Of course, the orientation predicate can already be found in the kernel, but you can follow this example to filter your own predicates. It uses the fast but inexact predicate based on interval arithmetic for filtering and the slow but exact predicate based on multi-precision floats when the filtering predicate fails.
File Filtered_kernel/Filtered_predicate.cpp
Types | |
typedef FP::result_type | result_type |
The return type of the function operators. More... | |
Creation | |
Filtered_predicate () | |
Default constructor. | |
Operations | |
template<class ... A> | |
result_type | operator() (A a...) |
The function operator for predicates. | |
typedef FP::result_type CGAL::Filtered_predicate< EP, FP, C2E, C2F >::result_type |
The return type of the function operators.
It must also be the same type as EP::result_type
.