@ -26,13 +26,14 @@
*/
/** @file
* @ brief Function @ ref Magnum : : MeshTools : : removeDuplicates ( )
* @ brief Function @ ref Magnum : : MeshTools : : removeDuplicatesInPlace ( ) , @ ref Magnum : : MeshTools : : removeDuplicatesIndexedInPlace ( ) , @ ref Magnum : : MeshTools : : removeDuplicates ( )
*/
# include <limits>
# include <numeric>
# include <unordered_map>
# include <vector>
# include <Corrade/Containers/Array.h>
# include <Corrade/Containers/ArrayViewStl.h>
# include <Corrade/Utility/MurmurHash2.h>
@ -51,11 +52,14 @@ namespace Implementation {
}
/**
@ brief Remove duplicate floating - point vector data from given array
@ param [ in , out ] data Input data array
@ param [ in ] epsilon Epsilon value , vertices nearer than this distance will be
@ brief Remove duplicate floating - point vector data from given array in - place
@ param [ in , out ] data Data array , duplicate items will be cut away with order
preserved
@ param [ in ] epsilon Epsilon value , vertices closer than this distance will be
melt together
@ return Index array and unique data
@ return Size of unique prefix in the cleaned up @ p data array and the resulting
index array
@ m_since_latest
Removes duplicate data from the array by collapsing them into buckets of size
@ p epsilon . First vector in given bucket is used , other ones are thrown away ,
@ -63,57 +67,82 @@ no interpolation is done. Note that this function is meant to be used for
floating - point data ( or generally with non - zero @ p epsilon ) , for discrete data
the usual sorting method is much more efficient .
If you want to remove duplicate data from an already indexed array , first
remove duplicates as if the array wasn ' t indexed at all and then use
@ ref duplicate ( ) to combine the two index arrays :
If you want to remove duplicate data from an already indexed array , use
@ ref removeDuplicatesIndexedInPlace ( ) instead . See also
@ ref removeDuplicates ( std : : vector < Vector > & , typename Vector : : Type ) for a
variant operating on a STL vector .
*/
template < class Vector > std : : pair < Containers : : Array < UnsignedInt > , std : : size_t > removeDuplicatesInPlace ( const Containers : : StridedArrayView1D < Vector > & data , typename Vector : : Type epsilon = Math : : TypeTraits < typename Vector : : Type > : : epsilon ( ) ) ;
/**
@ brief Remove duplicate floating - point vector data from a STL vector in - place
@ param [ in , out ] data Data array , duplicate items will be cut away with order
preserved and the size shrunk to just the unique prefix
@ param [ in ] epsilon Epsilon value , vertices closer than this distance will be
melt together
@ return Resulting index array
@ snippet MagnumMeshTools . cpp removeDuplicates1
Similar to the above , except that it ' s operating on a @ ref std : : vector , which
gets shrunk as a result ( instead of the prefix size being returned ) . This
variant is useful together with @ ref combineIndexedArrays ( ) to remove
duplicates in multiple incidental arrays - - - first remove duplicates in each
array separately and then combine the resulting index arrays to single index
array , and reorder the data accordingly :
Removing duplicates in multiple indcidental arrays is also possible - - - first
remove duplicates in each array separately and then use @ ref combineIndexedArrays ( )
to combine the resulting index arrays to single index array , and reorder the
data accordingly :
@ snippet MagnumMeshTools . cpp removeDuplicates - multiple
*/
template < class Vector > std : : vector < UnsignedInt > removeDuplicates ( std : : vector < Vector > & data , typename Vector : : Type epsilon = Math : : TypeTraits < typename Vector : : Type > : : epsilon ( ) ) ;
@ snippet MagnumMeshTools . cpp removeDuplicates2
/**
@ brief Remove duplicates from indexed floating - point vector data in - place
@ param [ in , out ] indices Index array , which will get remapped to list just
unique vertices
@ param [ in , out ] data Data array , duplicate items will be cut away with order
preserved
@ param [ in ] epsilon Epsilon value , vertices closer than this distance will
be melt together
@ return Size of unique prefix in the cleaned up @ p data array
@ m_since_latest
Compared to @ ref removeDuplicatesInPlace ( ) this variant is more suited for data
that is already indexed as it works on the existing index array instead of
allocating a new one .
*/
template < class Vector > std : : vector < UnsignedInt > removeDuplicates ( std : : vector < Vector > & data , typename Vector : : Type epsilon = Math : : TypeTraits < typename Vector : : Type > : : epsilon ( ) ) {
template < class IndexType , class Vector > std : : size_t removeDuplicatesIndexedInPlace ( const Containers : : StridedArrayView1D < IndexType > & indices , const Containers : : StridedArrayView1D < Vector > & data , typename Vector : : Type epsilon = Math : : TypeTraits < typename Vector : : Type > : : epsilon ( ) ) {
/* Somehow ~IndexType{} doesn't work for < 4byte types, as the result is
int ( - 1 ) instead of the type I want */
CORRADE_ASSERT ( data . size ( ) < = IndexType ( - 1 ) , " MeshTools::removeDuplicatesIndexedInPlace(): a " < < sizeof ( IndexType ) < < Debug : : nospace < < " -byte index type is too small for " < < data . size ( ) < < " vertices " , { } ) ;
/* Get bounds. When NaNs appear, those will get collapsed together when
you ' re lucky , or cause the whole data to disappear when you ' re not - - it
needs a much more specialized handling to be robust . */
std : : pair < Vector , Vector > minmax = Math : : minmax < Vector > ( data ) ;
std : : pair < Vector , Vector > minmax = Math : : minmax ( data ) ;
/* Make epsilon so large that std::size_t can index all vectors inside the
bounds . */
epsilon = Math : : max ( epsilon , typename Vector : : Type ( ( minmax . second - minmax . first ) . max ( ) / ~ std : : size_t { } ) ) ;
/* Resulting index array. Because we'll be remapping these, we need to
start from a 0. . n sequence . */
std : : vector < UnsignedInt > indices ( data . size ( ) ) ;
std : : iota ( indices . begin ( ) , indices . end ( ) , 0 ) ;
/* Table containing original vector index for each discretized vector.
Reserving more buckets than necessary ( i . e . as if each vector was
unique ) . */
std : : unordered_map < Math : : Vector < Vector : : Size , std : : size_t > , UnsignedInt , Implementation : : VectorHash < Vector : : Size > > table ( data . size ( ) ) ;
std : : size_t dataSize = data . size ( ) ;
std : : unordered_map < Math : : Vector < Vector : : Size , std : : size_t > , UnsignedInt , Implementation : : VectorHash < Vector : : Size > > table ( dataSize ) ;
/* Index array that'll be filled in each pass and then used for remapping
the ` indices ` */
std : : vector < UnsignedInt > remapping ( data . size ( ) ) ;
Container s: : Array < UnsignedInt > remapping { Containers : : NoInit , dataSize } ;
/* First go with original coordinates, then move them by epsilon/2 in each
direction . */
Vector moved ;
for ( std : : size_t moving = 0 ; moving < = Vector : : Size ; + + moving ) {
/* Clear the table for this pass */
table . clear ( ) ;
/* Go through all vectors */
for ( std : : size_t i = 0 ; i ! = data . size ( ) ; + + i ) {
for ( std : : size_t i = 0 ; i ! = dataSize ; + + i ) {
/* Try to insert new vertex into the table */
const Math : : Vector < Vector : : Size , std : : size_t > v { ( data [ i ] + moved - minmax . first ) / epsilon } ;
const auto result = table . emplace ( v , table . size ( ) ) ;
/* Add the (either new or already existing) index into index array */
/* Add the (either new or already existing) index into the array */
remapping [ i ] = result . first - > second ;
/* If this is a new combination, copy the data to new (earlier)
@ -121,13 +150,9 @@ template<class Vector> std::vector<UnsignedInt> removeDuplicates(std::vector<Vec
present in the [ 0 , table . size ( ) - 1 ) range from previous
iterations so we aren ' t overwriting anything . */
if ( result . second & & i ! = table . size ( ) - 1 )
data [ table . size ( ) - 1 ] = data [ i ] ;
data [ table . size ( ) - 1 ] = data [ i ] ;
}
/* Shrink the data array */
CORRADE_INTERNAL_ASSERT ( data . size ( ) > = table . size ( ) ) ;
data . resize ( table . size ( ) ) ;
/* Remap the resulting index array */
for ( auto & i : indices ) i = remapping [ i ] ;
@ -137,8 +162,31 @@ template<class Vector> std::vector<UnsignedInt> removeDuplicates(std::vector<Vec
/* Move vertex coordinates by epsilon/2 in the next direction */
moved = Vector ( ) ;
moved [ moving ] = epsilon / 2 ;
/* Next time go only through the unique prefix; clear the table for the
next pass */
dataSize = table . size ( ) ;
table . clear ( ) ;
}
CORRADE_INTERNAL_ASSERT ( data . size ( ) > = dataSize ) ;
return dataSize ;
}
template < class Vector > std : : pair < Containers : : Array < UnsignedInt > , std : : size_t > removeDuplicatesInPlace ( const Containers : : StridedArrayView1D < Vector > & data , typename Vector : : Type epsilon ) {
/* A trivial index array that'll be remapped and returned after */
Containers : : Array < UnsignedInt > indices { Containers : : NoInit , data . size ( ) } ;
std : : iota ( indices . begin ( ) , indices . end ( ) , 0 ) ;
const std : : size_t size = removeDuplicatesIndexedInPlace ( Containers : : stridedArrayView ( indices ) , data , epsilon ) ;
return { std : : move ( indices ) , size } ;
}
template < class Vector > std : : vector < UnsignedInt > removeDuplicates ( std : : vector < Vector > & data , typename Vector : : Type epsilon ) {
/* A trivial index array that'll be remapped and returned after */
std : : vector < UnsignedInt > indices ( data . size ( ) ) ;
std : : iota ( indices . begin ( ) , indices . end ( ) , 0 ) ;
const std : : size_t size = removeDuplicatesIndexedInPlace ( Containers : : stridedArrayView ( indices ) , Containers : : stridedArrayView ( data ) , epsilon ) ;
data . resize ( size ) ;
return indices ;
}
Vladimír Vondruš
6 years ago