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#include <thrust/device_vector.h>
#include <thrust/remove.h>
#include <thrust/unique.h>
#include <thrust/binary_search.h>
#include <thrust/sort.h>
#include <iostream>
/*
* This example "welds" triangle vertices together by taking as
* input "triangle soup" and eliminating redundant vertex positions
* and shared edges. A connected mesh is the result.
*
*
* Input: 9 vertices representing a mesh with 3 triangles
*
* Mesh Vertices
* ------ (2) (5)--(4) (8)
* | \ 2| \ | \ \ | | \
* | \ | \ <-> | \ \ | | \
* | 0 \| 1 \ | \ \ | | \
* ----------- (0)--(1) (3) (6)--(7)
*
* (vertex 1 equals vertex 3, vertex 2 equals vertex 5, ...)
*
* Output: mesh representation with 5 vertices and 9 indices
*
* Vertices Indices
* (1)--(3) [(0,2,1),
* | \ | \ (2,3,1),
* | \ | \ (2,4,3)]
* | \| \
* (0)--(2)--(4)
*/
// define a 2d float vector
typedef thrust::tuple<float,float> vec2;
int main(void)
{
// allocate memory for input mesh representation
thrust::device_vector<vec2> input(9);
input[0] = vec2(0,0); // First Triangle
input[1] = vec2(1,0);
input[2] = vec2(0,1);
input[3] = vec2(1,0); // Second Triangle
input[4] = vec2(1,1);
input[5] = vec2(0,1);
input[6] = vec2(1,0); // Third Triangle
input[7] = vec2(2,0);
input[8] = vec2(1,1);
// allocate space for output mesh representation
thrust::device_vector<vec2> vertices = input;
thrust::device_vector<unsigned int> indices(input.size());
// sort vertices to bring duplicates together
thrust::sort(vertices.begin(), vertices.end());
// find unique vertices and erase redundancies
vertices.erase(thrust::unique(vertices.begin(), vertices.end()), vertices.end());
// find index of each input vertex in the list of unique vertices
thrust::lower_bound(vertices.begin(), vertices.end(),
input.begin(), input.end(),
indices.begin());
// print output mesh representation
std::cout << "Output Representation" << std::endl;
for(size_t i = 0; i < vertices.size(); i++)
{
vec2 v = vertices[i];
std::cout << " vertices[" << i << "] = (" << thrust::get<0>(v) << "," << thrust::get<1>(v) << ")" << std::endl;
}
for(size_t i = 0; i < indices.size(); i++)
{
std::cout << " indices[" << i << "] = " << indices[i] << std::endl;
}
return 0;
}