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