I'm working with flann library with point clouds. I have this adapter method that transform my own points to a flann-usable points
flann::Matrix<float> * converterFlann::convertArray(vector<Point *> *P){
float points[P->size()*3];
int j = 0;
for (int i = 0; i<P->size(); i++){
points[j] = P->at(i)->getX(); j++;
points[j] = P->at(i)->getY(); j++;
points[j] = P->at(i)->getZ(); j++;
}
P->at(0)->print();
cout << points[0] << " " << points[1] << " " << points[2] << endl;
flann::Matrix<float> *nari = new flann::Matrix<float>(points, P->size(), 3);
cout << *nari[0][0] << " " << *nari[0][1] << " " << *nari[0][2] << endl;
return nari;
}
And the output of this method is
Printing my point: (-0.06325, 0.0359793, 0.0420873) Index: 0
Printing from points array: -0.06325 0.0359793 0.0420873
Printing from flann: -0.06325 -0.06275 -0.0645
I don't understand why printing from flann::Matrix, Y and Z are different. I've been looking for some documentation about storing procedure of flann::Matrix but I'm not able to find any answer. I thing that my array-type access is correct but it doesn't work.
Thanks in advance. :D
Related
So I've made a basic polynomial class in C++ which stores the coefficients of these polynomials dynamically on the heap. I'm currently in the process of overloading operators so that I can add/subtract polynomials together in order to simplify them etc.
However I'm getting unexpected results when I try to overload the * operator. It looks like instead of returning the value of an index in the array it is returning the position of the array.
This is my *operator method in my .cpp file:
Polynomial Polynomial::operator*(Polynomial p) {
int maxDegree = (degree)+(p.degree - 1);
int *intArray3 = new int[maxDegree];
int i, j;
for (int i = 0; i < degree; i++) {
for (int j = 0; j < p.degree; j++) {
cout << getCoef(i) << " * " << p.getCoef(j) << " = " << getCoef(i)*p.getCoef(j) << endl;
intArray3[j] += (getCoef(i))*(p.getCoef(j));
cout << " intArray3[" << j << "] contains : " << intArray3[j] << endl;
}
}
return Polynomial(maxDegree, intArray3);}
The lines:
cout << getCoef(i) << " * " << p.getCoef(j) << " = " << getCoef(i)*p.getCoef(j) << endl;
and
cout << " intArray3[" << j << "] contains : " << intArray3[j] << endl;
return
10 * 1 = 10
intArray3[0] contains : -842150441
in my console. I'm assuming that the problem lies with my use of pointers somewhere but I can't for the life of me think why. I implemented this overload in a similar way to my + and - overloads and they work fine. Any assistance would be greatly appreciated. Cheers.
I am trying to load freetype chars, stuff them into a texture as subimages and then render them instanced.
While most of it seems to work, right now I have a problem with storing the texture coordinates into a glm::mat2x4 matrix.
As can be seen below each character has a struct with information I right now deem necessary, including a matrix called face, which should store the texture coordinates.
But when it comes to assigning the coordinates, after leaving the loop in which it takes place, suddenly all the values go crazy, without any (wanted/ intended) operation taking place from my side.
After creating the texture atlas with freetype and putting all my structs into the map, I assign the width and height of my texture aw & ah to a storage class called c_atlas.
I calculate the texture coordinates in the loop shown below, make the glm::mat2x4 a 0.0f matrix and then stuff them into it. Couting them into the console gives the values I want.
After leaving the for loop I start another one, browsing over the matrix and cout them into the console, which gives me more or less random values in the range of e^-23 to e^32.
All of this happens in namespace foo and is called in a constructor of a class in the same namespace (sth. like this:)
foo::class::constructor()
{
call_function();
}
int main()
{
foo::class c;
c.call_function();
}
I crafted a minimum working example, but unfortunatly I am not able to replicate the error.
So I have the following loop running (a part of call_function():
namespace foo
{
namespace alphabet
{
const char path_arial[] = "res/font/consola.ttf";
class character
{
public:
glm::vec2 advance;
glm::vec2 bearing;
glm::vec2 size;
glm::vec2 offset;
glm::mat2x4 face;
};
std::map<char, character> char_map;
FT_Library m_ftlib;
FT_Face m_ftface;
GLuint m_VBO, m_VAO;
}
c_atlas ascii;
}
void foo::call_function()
{
//creating all the charactur structs with freetype and store them in the char_map
std::ofstream f("atlas_data.csv", std::ios::openmode::_S_app);
f << "letter;topleft.x;topleft.y;topright.x;topright.y;bottomright.x;bottomright.y;bottomleft.x;bottomleft.y" << std::endl;
for(auto c : alphabet::char_map)
{
std::cout << "b4: " << c.second.offset.x;
c.second.offset /= glm::vec2(aw,ah);
std::cout << "\nafter: " << c.second.offset.x << std::endl;
glm::vec2 ts = c.second.size/glm::vec2(aw,ah);
//couts the right values
uint16_t n = 0;
c.second.face = glm::mat2x4(0.0f);
for(uint16_t i = 0; i < 4; ++i)
{
std::cout << c.first << " at init:\n";
std::cout << c.second.face[0][i] << "\n";
std::cout << c.second.face[1][i] << std::endl;
}
//couts the right values
c.second.face[0][n++] = c.second.offset.x;
c.second.face[0][n++] = c.second.offset.y;
c.second.face[0][n++] = c.second.offset.x+ts.x;
c.second.face[0][n++] = c.second.offset.y;
n = 0;
c.second.face[1][n++]= c.second.offset.x+ts.x;
c.second.face[1][n++] = c.second.offset.y+ts.y;
c.second.face[1][n++] = c.second.offset.x;
c.second.face[1][n++]= c.second.offset.y+ts.y;
for(uint16_t i = 0; i < 4; ++i)
{
std::cout << c.first << " assigned:\n";
std::cout << c.second.face[0][i] << "\n";
std::cout << c.second.face[1][i] << std::endl;
}
//still couts the right values
f << (char)c.first << ";" << c.second.face[0].x << ";" << c.second.face[0].y << ";" << c.second.face[0].z << ";" << c.second.face[0].w << ";" << c.second.face[1].x << ";" << c.second.face[1].y << ";" << c.second.face[1].z << ";" << c.second.face[1].w << std::endl;
//the file also have the right values
}
f.close();
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
//yet here all the values totally off track, i.e. e^32 or e^-23 (while they should all be between 0.01f - 1.0f)
for(auto i : alphabet::char_map)
{
std::cout << "\ntopleft:\n";
std::cout << "X: " << i.second.face[0].x << " | " << "Y: " << i.second.face[0].x;
std::cout << "\ntopright:\n";
std::cout << "X: " << i.second.face[0].z << " | " << "Y: " << i.second.face[0].w;
std::cout << "\nbotleft:\n";
std::cout << "X: " << i.second.face[1].x << " | " << "Y: " << i.second.face[1].x;
std::cout << "\nbotright:\n";
std::cout << "X: " << i.second.face[1].z << " | " << "Y: " << i.second.face[1].w;
}
}
my mwe:
#include <iostream>
#include <string>
#include "glm/glm.hpp"
#include "GL/gl.h"
#include <map>
struct bin
{
glm::mat2x4 mat;
};
int main( int argc, char *argv[] )
{
std::map<char, bin> bucket;
uint16_t r = 0;
for(uint16_t n = 0; n < 7; ++n)
{
glm::vec4 v = glm::vec4(0.12128f, 0.12412f, 0.15532f, 0.23453f);
bin b;
r = 0;
b.mat[0][r++] = v.x;
b.mat[0][r++] = v.y;
b.mat[0][r++] = v.z;
b.mat[0][r++] = v.w;
r = 0;
b.mat[1][r++] = v.x;
b.mat[1][r++] = v.y;
b.mat[1][r++] = v.z;
b.mat[1][r++] = v.w;
bucket[n] = b;
}
for(auto it : bucket)
{
r = 0;
std::cout << "0:\t" << it.second.mat[0][0] << "\t" << it.second.mat[0][1] << "\t" << it.second.mat[0][2] << "\t" << it.second.mat[0][3] << "\n";
r = 0;
std::cout << "1:\t" << it.second.mat[1][0] << "\t" << it.second.mat[1][1] << "\t" << it.second.mat[1][2] << "\t" << it.second.mat[1][3] << std::endl;
}
return 0;
}
Right now I am totally lost, especially as my mwe works fine.
I am clueless what goes wrong after leaving the for-loop, so thanks for any thought on that!
Indeed, I could just rewrite that section and hope it would work - as my mwe does. But I would like to find out/ get help on finding out what exactly happens between the "assign" for loop and the "retrieve" for loop. Any ideas on that?
I made it work for me now:
Appartenly assigning the values this way:
for(auto c : alphabet::char_map)
{
c.second.face[0][n++] = c.second.offset.x;
//and so on
}
Did not work properly (for whatever reason..)
Changing this into a for(uint16_t i = 32; i < 128; ++i) worked for me. Also it was just the assigning loop, the auto-iterating ofer the map elsewhere works just fine.
I'm having trouble getting the size of a vector by dot-walking from a parent vector into the one in question. I have verified that calling the function myfunc 1 2 3 4 5 creates five Person objects and puts them in the left vector. But when I try to get that same size to return by dot-walking from bridge to left, I get 0 as the size.
What am I doing wrong?
int main(int argc, char* argv[]) {
Person* p_ptr;
int id_source = 0;
vector<Person> left;
vector<Person> right;
bridge.push_back(left);
bridge.push_back(right);
cout << "bridge.size() = " << bridge.size() << endl;
for (int i = 1; i < argc; i++) {
id_source++;
cout << "Creating Person with crossing speed of " << argv[i] << " and id of " << id_source << endl;
p_ptr = new Person(atoi(argv[i]), id_source);
left.push_back(*p_ptr);
}
/*SIZE TESTING*/
cout << "Left side of bridge has " << left.size() << " people on it " << endl;
cout << "bridge.at(0).size() = " << bridge.at(0).size() << endl;
cout << "bridge.at(1).size() = " << bridge.at(1).size() << endl;
int slowest_id = get_slowest(0);
for (int i = 0; i < left.size(); i++) {
if (slowest_id == left.at(i).get_id()) {
p_ptr = &left.at(i);
}
}
cout << "The slowest person has id of " << slowest_id << " and speed of " << p_ptr->get_crossing_time() << endl;
}
}
left and bridge[0] are two different lists. When you call bridge.push_back(left) you make a copy of the current left list (which is empty). Elements added later will not be in the bridge version.
Background: I am implementing the nearest neighbor algorithm for the Traveling-Salesman-Problem. I need to calculate the distance traveled for the tour as well as keep track of the order of points visited. I have defined a point class with instance variables x and y and a function calcDist for calculating the distance between two points. I start by storing all of the points in a std::unordered_set named points, creating an empty std::vector named path to store the tour path, and assigning the starting point to startPoint, and pass these to my nearestNeighbor() function:
void nearestNeighbor(unordered_set<Point, PointHasher> points, vector<Point> &path, Point startPoint) {
// Declare variables
unordered_set<Point, PointHasher>::iterator it;
Point currentLocation, possibleNeighbor, nearestNeighbor;
double totalDist = 0;
int pointsCount = path.capacity() - 1;
// Set the starting location
it = points.find(startPoint);
currentLocation = *it;
path[0] = currentLocation;
points.erase(currentLocation);
cout << "Start location: " << path[0].x << ", " << path[0].y << endl;
// Create the path
for (int i = 1; points.size() > 0; i++) {
double minDist = -1;
// Find the current location's nearest neighbor
for (it = points.begin(); it != points.end(); it++) {
possibleNeighbor = *it;
int currentDist = currentLocation.calcDist(possibleNeighbor);
if (minDist == -1 || currentDist < minDist) {
minDist = currentDist;
nearestNeighbor = possibleNeighbor;
}
}
// Record nearest neighbor data and prepare for the next iteration
currentLocation = nearestNeighbor;
path[i] = currentLocation;
points.erase(currentLocation);
totalDist += minDist;
cout << "Nearest neighbor: " << path[i].x << ", " << path[i].y << endl;
}
// Return to the starting location
path[pointsCount] = startPoint;
cout << "End location: " << startPoint.x << ", " << startPoint.y << endl;
cout << "Path:" << endl;
for (int i = 0; i < path.size(); i++) {
cout << path[0].x << ", " << path[0].y << endl;
}
cout << "Total distance: " << totalDist << endl;
}
The problem is that once the program exits the outer for loop, all the points in path are overwritten somehow. To see what I mean, here is the output:
Start location: 3, 4
Nearest neighbor: 6, 8
Nearest neighbor: 11, 7
Nearest neighbor: 50, 8
End location: 3, 4
Path:
3, 4
3, 4
3, 4
3, 4
3, 4
Total distance: 49
Press any key to continue . . .
I am thinking this either has to be a problem with pointers/addresses of the vector elements, or something with scope since the problem happens after exiting the for loop. I have even tried printing the path[1] after each iteration to see when it gets changed, but it is correct throughout the loop, and only changes in the output at the end. Any thoughts? I am stumped. And if you have made it this far, thank you very much for your time.
you are always outputing the coordinates of path[0] man
for (int i = 0; i < path.size(); i++) {
cout << path[0].x << ", " << path[0].y << endl;
}
You have
for (int i = 0; i < path.size(); i++) {
cout << path[0].x << ", " << path[0].y << endl;
}
This doesn't iterate through i. Change your 0 to i and you'll likely see something more helpful:
for (int i = 0; i < path.size(); i++) {
cout << path[i].x << ", " << path[i].y << endl;
}
Edit: Change path[i] = currentLocation; to path.push_back(currentLocation); - this will automatically increase the size of your path vector to fit the new elements.
void nearestNeighbor(
unordered_set<Point, PointHasher> points,
vector<Point> &path,
Point startPoint,
double &totalDist) // note the new variable passed here
{
// Declare variables
unordered_set<Point, PointHasher>::iterator it;
Point currentLocation, possibleNeighbor, nearestNeighbor;
// double totalDist = 0; Remove this line
// int pointsCount = path.capacity() - 1; And this
// Set the starting location
it = points.find(startPoint);
currentLocation = *it;
path.push_back(currentLocation); // Changed this line
points.erase(currentLocation);
cout << "Start location: " << path[0].x << ", " << path[0].y << endl;
// Create the path
for (int i = 1; points.size() > 0; i++) {
double minDist = -1;
// Find the current location's nearest neighbor
for (it = points.begin(); it != points.end(); it++) {
possibleNeighbor = *it;
int currentDist = currentLocation.calcDist(possibleNeighbor);
if (minDist == -1 || currentDist < minDist) {
minDist = currentDist;
nearestNeighbor = possibleNeighbor;
}
}
// Record nearest neighbor data and prepare for the next iteration
currentLocation = nearestNeighbor;
path.push_back(currentLocation); // And this line
points.erase(currentLocation);
totalDist += minDist;
cout << "Nearest neighbor: " << path[i].x << ", " << path[i].y << endl;
}
// Return to the starting location
path.push_back(startPoint); // And here also!
cout << "End location: " << startPoint.x << ", " << startPoint.y << endl; // This I didn't change,
// but perhaps you should make it reflect the last point in the vector,
// not the start point which is supposed to be the last point in the vector
cout << "Path:" << endl;
for (int i = 0; i < path.size(); i++) {
cout << path[i].x << ", " << path[i].y << endl;
}
cout << "Total distance: " << totalDist << endl;
}
I do not see any place which grows the size of the path vector.
I suspect that you're passing an empty std::vector, for the second argument, and as soon as you hit path[0]=currentLocation; ... undefined behavior.
Also, I don't think that capacity() does what you think it does.
That, and, as others have pointed out, you're not outputing the contents of the array correctly, but that's a minor problem. The major problem here is that this program is likely scribbling over and corrupting the heap.
I have never used CGAL and have got almost no C/C++ experience. But following
Google I have however managed to compile the example "Alpha_shapes_3"
(\CGAL-4.1-beta1\examples\Alpha_shapes_3) on a Windows 7 64bit machine using
visual studio 2010.
Now if we check the source code for the program "ex_alpha_shapes_3" we
notice that a data file called "bunny_1000" is red where the 3d point
cluster resides.
Now my question is how can I change the source code so that after the alpha
shape is computed for the given points, surface mesh of the alpha shape is
saved/wrote in an external file. It can be simply the list of polygons and
their respective 3D vertices. I guess these polygons will be defining the
surface mesh of the alpha shape. If I can do that I can see the output of
the alpha shape generation program in an external tool I am familiar with.
I know this is very straightforward but I could not figure this out with my
limited knowledge of CGAL.
I know you gueys have the code but I am pasting it again for completion.
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Delaunay_triangulation_3.h>
#include <CGAL/Alpha_shape_3.h>
#include <fstream>
#include <list>
#include <cassert>
typedef CGAL::Exact_predicates_inexact_constructions_kernel Gt;
typedef CGAL::Alpha_shape_vertex_base_3<Gt> Vb;
typedef CGAL::Alpha_shape_cell_base_3<Gt> Fb;
typedef CGAL::Triangulation_data_structure_3<Vb,Fb> Tds;
typedef CGAL::Delaunay_triangulation_3<Gt,Tds> Triangulation_3;
typedef CGAL::Alpha_shape_3<Triangulation_3> Alpha_shape_3;
typedef Gt::Point_3 Point;
typedef Alpha_shape_3::Alpha_iterator Alpha_iterator;
int main()
{
std::list<Point> lp;
//read input
std::ifstream is("./data/bunny_1000");
int n;
is >> n;
std::cout << "Reading " << n << " points " << std::endl;
Point p;
for( ; n>0 ; n--) {
is >> p;
lp.push_back(p);
}
// compute alpha shape
Alpha_shape_3 as(lp.begin(),lp.end());
std::cout << "Alpha shape computed in REGULARIZED mode by default"
<< std::endl;
// find optimal alpha value
Alpha_iterator opt = as.find_optimal_alpha(1);
std::cout << "Optimal alpha value to get one connected component is "
<< *opt << std::endl;
as.set_alpha(*opt);
assert(as.number_of_solid_components() == 1);
return 0;
}
After searching a lot in the internet I found that probably we need to use something like
std::list<Facet> facets;
alpha_shape.get_alpha_shape_facets
(
std::back_inserter(facets),Alpha_shape::REGULAR
);
But I am still completely clueless how to use this in the above code!
As documented here, a facet is a pair (Cell_handle c,int i) defined as the facet in c opposite to the vertex of index i.
On this page, you have the description of how the vertex indices of a cell are.
In the following code sample, I added a small output that prints an OFF file on cout by duplicating the vertices. To do something clean, you can either use a std::map<Alpha_shape_3::Vertex_handle,int> to associate a unique index per vertex or add an info to the vertices like in those examples.
/// collect all regular facets
std::vector<Alpha_shape_3::Facet> facets;
as.get_alpha_shape_facets(std::back_inserter(facets), Alpha_shape_3::REGULAR);
std::stringstream pts;
std::stringstream ind;
std::size_t nbf=facets.size();
for (std::size_t i=0;i<nbf;++i)
{
//To have a consistent orientation of the facet, always consider an exterior cell
if ( as.classify( facets[i].first )!=Alpha_shape_3::EXTERIOR )
facets[i]=as.mirror_facet( facets[i] );
CGAL_assertion( as.classify( facets[i].first )==Alpha_shape_3::EXTERIOR );
int indices[3]={
(facets[i].second+1)%4,
(facets[i].second+2)%4,
(facets[i].second+3)%4,
};
/// according to the encoding of vertex indices, this is needed to get
/// a consistent orienation
if ( facets[i].second%2==0 ) std::swap(indices[0], indices[1]);
pts <<
facets[i].first->vertex(indices[0])->point() << "\n" <<
facets[i].first->vertex(indices[1])->point() << "\n" <<
facets[i].first->vertex(indices[2])->point() << "\n";
ind << "3 " << 3*i << " " << 3*i+1 << " " << 3*i+2 << "\n";
}
std::cout << "OFF "<< 3*nbf << " " << nbf << " 0\n";
std::cout << pts.str();
std::cout << ind.str();
Here is my code, which outputs vtk file for visualization in Paraview. Comparing with slorior's solutions, no duplicated points are saved in the file. But my code is just for the visualization, if you need to figure out the exterior or interior simplexes, you should modify the code to get these results.
void writevtk(Alpha_shape_3 &as, const std::string &asfile) {
// http://cgal-discuss.949826.n4.nabble.com/Help-with-filtration-and-filtration-with-alpha-values-td4659524.html#a4659549
std::cout << "Information of the Alpha_Complex:\n";
std::vector<Alpha_shape_3::Cell_handle> cells;
std::vector<Alpha_shape_3::Facet> facets;
std::vector<Alpha_shape_3::Edge> edges;
// tetrahedron = cell, they should be the interior, it is inside the 3D space
as.get_alpha_shape_cells(std::back_inserter(cells), Alpha_shape_3::INTERIOR);
// triangles
// for the visualiization, don't need regular because tetrahedron will show it
//as.get_alpha_shape_facets(std::back_inserter(facets), Alpha_shape_3::REGULAR);
as.get_alpha_shape_facets(std::back_inserter(facets), Alpha_shape_3::SINGULAR);
// edges
as.get_alpha_shape_edges(std::back_inserter(edges), Alpha_shape_3::SINGULAR);
std::cout << "The alpha-complex has : " << std::endl;
std::cout << cells.size() << " cells as tetrahedrons" << std::endl;
std::cout << facets.size() << " triangles" << std::endl;
std::cout << edges.size() << " edges" << std::endl;
size_t tetra_num, tri_num, edge_num;
tetra_num = cells.size();
tri_num = facets.size();
edge_num = edges.size();
// vertices: points <-> id
std::map<Point, size_t> points;
size_t index = 0;
// finite_.. is from DT class
for (auto v_it = as.finite_vertices_begin(); v_it != as.finite_vertices_end(); v_it++) {
points[v_it->point()] = index;
index++;
}
// write
std::ofstream of(asfile);
of << "# vtk DataFile Version 2.0\n\nASCII\nDATASET UNSTRUCTURED_GRID\n\n";
of << "POINTS " << index << " float\n";
for (auto v_it = as.finite_vertices_begin(); v_it != as.finite_vertices_end(); v_it++) {
of << v_it->point() << std::endl;
}
of << std::endl;
of << "CELLS " << tetra_num + tri_num + edge_num << " " << 5 * tetra_num + 4 * tri_num + 3 * edge_num << std::endl;
for (auto cell:cells) {
size_t v0 = points.find(cell->vertex(0)->point())->second;
size_t v1 = points.find(cell->vertex(1)->point())->second;
size_t v2 = points.find(cell->vertex(2)->point())->second;
size_t v3 = points.find(cell->vertex(3)->point())->second;
of << "4 " << v0 << " " << v1 << " " << v2 << " " << v3 << std::endl;
}
// https://doc.cgal.org/latest/TDS_3/classTriangulationDataStructure__3.html#ad6a20b45e66dfb690bfcdb8438e9fcae
for (auto tri_it = facets.begin(); tri_it != facets.end(); ++tri_it) {
of << "3 ";
auto tmp_tetra = tri_it->first;
for (int i = 0; i < 4; i++) {
if (i != tri_it->second) {
of << points.find(tmp_tetra->vertex(i)->point())->second << " ";
}
}
of << std::endl;
}
// https://doc.cgal.org/latest/TDS_3/classTriangulationDataStructure__3.html#af31db7673a6d7d28c0bb90a3115ac695
for (auto e : edges) {
of << "2 ";
auto tmp_tetra = e.get<0>();
int p1, p2;
p1 = e.get<1>();
p2 = e.get<2>();
of << points.find(tmp_tetra->vertex(p1)->point())->second << " "
<< points.find(tmp_tetra->vertex(p2)->point())->second << std::endl;
}
of << std::endl;
of << "CELL_TYPES " << tetra_num + tri_num + edge_num << std::endl;
for (int i = 0; i < tetra_num; i++) {
of << "10 ";
}
for (int i = 0; i < tri_num; i++) {
of << "5 ";
}
for (int i = 0; i < edge_num; i++) {
of << "3 ";
}
of << std::endl;
of.close();
}