259 lines
10 KiB
C++
259 lines
10 KiB
C++
/* ADMesh -- process triangulated solid meshes
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* Copyright (C) 1995, 1996 Anthony D. Martin <amartin@engr.csulb.edu>
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* Copyright (C) 2013, 2014 several contributors, see AUTHORS
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Questions, comments, suggestions, etc to
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* https://github.com/admesh/admesh/issues
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <vector>
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#include <boost/log/trivial.hpp>
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#include <boost/nowide/cstdio.hpp>
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#include "stl.h"
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void stl_generate_shared_vertices(stl_file *stl, indexed_triangle_set &its)
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{
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// 3 indices to vertex per face
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its.indices.assign(stl->stats.number_of_facets, stl_triangle_vertex_indices(-1, -1, -1));
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// Shared vertices (3D coordinates)
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its.vertices.clear();
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its.vertices.reserve(stl->stats.number_of_facets / 2);
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// A degenerate mesh may contain loops: Traversing a fan will end up in an endless loop
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// while never reaching the starting face. To avoid these endless loops, traversed faces at each fan traversal
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// are marked with a unique fan_traversal_stamp.
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unsigned int fan_traversal_stamp = 0;
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std::vector<unsigned int> fan_traversal_facet_visited(stl->stats.number_of_facets, 0);
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for (uint32_t facet_idx = 0; facet_idx < stl->stats.number_of_facets; ++ facet_idx) {
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for (int j = 0; j < 3; ++ j) {
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if (its.indices[facet_idx][j] != -1)
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// Shared vertex was already assigned.
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continue;
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// Create a new shared vertex.
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its.vertices.emplace_back(stl->facet_start[facet_idx].vertex[j]);
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// Traverse the fan around the j-th vertex of the i-th face, assign the newly created shared vertex index to all the neighboring triangles in the triangle fan.
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int facet_in_fan_idx = facet_idx;
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bool edge_direction = false;
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bool traversal_reversed = false;
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int vnot = (j + 2) % 3;
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// Increase the
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++ fan_traversal_stamp;
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for (;;) {
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// Next edge on facet_in_fan_idx to be traversed. The edge is indexed by its starting vertex index.
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int next_edge = 0;
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// Vertex index in facet_in_fan_idx, which is being pivoted around, and which is being assigned a new shared vertex.
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int pivot_vertex = 0;
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if (vnot > 2) {
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// The edge of facet_in_fan_idx opposite to vnot is equally oriented, therefore
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// the neighboring facet is flipped.
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if (! edge_direction) {
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pivot_vertex = (vnot + 2) % 3;
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next_edge = pivot_vertex;
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} else {
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pivot_vertex = (vnot + 1) % 3;
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next_edge = vnot % 3;
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}
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edge_direction = ! edge_direction;
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} else {
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// The neighboring facet is correctly oriented.
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if (! edge_direction) {
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pivot_vertex = (vnot + 1) % 3;
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next_edge = vnot;
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} else {
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pivot_vertex = (vnot + 2) % 3;
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next_edge = pivot_vertex;
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}
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}
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its.indices[facet_in_fan_idx][pivot_vertex] = its.vertices.size() - 1;
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fan_traversal_facet_visited[facet_in_fan_idx] = fan_traversal_stamp;
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// next_edge is an index of the starting vertex of the edge, not an index of the opposite vertex to the edge!
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int next_facet = stl->neighbors_start[facet_in_fan_idx].neighbor[next_edge];
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if (next_facet == -1) {
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// No neighbor going in the current direction.
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if (traversal_reversed) {
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// Went to one limit, then turned back and reached the other limit. Quit the fan traversal.
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break;
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} else {
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// Reached the first limit. Now try to reverse and traverse up to the other limit.
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edge_direction = true;
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vnot = (j + 1) % 3;
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traversal_reversed = true;
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facet_in_fan_idx = facet_idx;
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}
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} else if (next_facet == facet_idx) {
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// Traversed a closed fan all around.
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// assert(! traversal_reversed);
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break;
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} else if (next_facet >= (int)stl->stats.number_of_facets) {
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// The mesh is not valid!
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// assert(false);
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break;
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} else if (fan_traversal_facet_visited[next_facet] == fan_traversal_stamp) {
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// Traversed a closed fan all around, but did not reach the starting face.
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// This indicates an invalid geometry (non-manifold).
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//assert(false);
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break;
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} else {
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// Continue traversal.
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// next_edge is an index of the starting vertex of the edge, not an index of the opposite vertex to the edge!
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vnot = stl->neighbors_start[facet_in_fan_idx].which_vertex_not[next_edge];
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facet_in_fan_idx = next_facet;
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}
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}
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}
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}
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}
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bool its_write_off(const indexed_triangle_set &its, const char *file)
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{
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/* Open the file */
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FILE *fp = boost::nowide::fopen(file, "w");
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if (fp == nullptr) {
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BOOST_LOG_TRIVIAL(error) << "stl_write_ascii: Couldn't open " << file << " for writing";
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return false;
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}
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fprintf(fp, "OFF\n");
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fprintf(fp, "%d %d 0\n", (int)its.vertices.size(), (int)its.indices.size());
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for (int i = 0; i < its.vertices.size(); ++ i)
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fprintf(fp, "\t%f %f %f\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
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for (uint32_t i = 0; i < its.indices.size(); ++ i)
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fprintf(fp, "\t3 %d %d %d\n", its.indices[i][0], its.indices[i][1], its.indices[i][2]);
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fclose(fp);
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return true;
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}
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bool its_write_vrml(const indexed_triangle_set &its, const char *file)
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{
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/* Open the file */
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FILE *fp = boost::nowide::fopen(file, "w");
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if (fp == nullptr) {
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BOOST_LOG_TRIVIAL(error) << "stl_write_vrml: Couldn't open " << file << " for writing";
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return false;
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}
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fprintf(fp, "#VRML V1.0 ascii\n\n");
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fprintf(fp, "Separator {\n");
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fprintf(fp, "\tDEF STLShape ShapeHints {\n");
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fprintf(fp, "\t\tvertexOrdering COUNTERCLOCKWISE\n");
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fprintf(fp, "\t\tfaceType CONVEX\n");
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fprintf(fp, "\t\tshapeType SOLID\n");
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fprintf(fp, "\t\tcreaseAngle 0.0\n");
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fprintf(fp, "\t}\n");
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fprintf(fp, "\tDEF STLModel Separator {\n");
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fprintf(fp, "\t\tDEF STLColor Material {\n");
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fprintf(fp, "\t\t\temissiveColor 0.700000 0.700000 0.000000\n");
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fprintf(fp, "\t\t}\n");
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fprintf(fp, "\t\tDEF STLVertices Coordinate3 {\n");
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fprintf(fp, "\t\t\tpoint [\n");
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int i = 0;
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for (; i + 1 < its.vertices.size(); ++ i)
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fprintf(fp, "\t\t\t\t%f %f %f,\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
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fprintf(fp, "\t\t\t\t%f %f %f]\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
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fprintf(fp, "\t\t}\n");
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fprintf(fp, "\t\tDEF STLTriangles IndexedFaceSet {\n");
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fprintf(fp, "\t\t\tcoordIndex [\n");
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for (size_t i = 0; i + 1 < its.indices.size(); ++ i)
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fprintf(fp, "\t\t\t\t%d, %d, %d, -1,\n", its.indices[i][0], its.indices[i][1], its.indices[i][2]);
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fprintf(fp, "\t\t\t\t%d, %d, %d, -1]\n", its.indices[i][0], its.indices[i][1], its.indices[i][2]);
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fprintf(fp, "\t\t}\n");
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fprintf(fp, "\t}\n");
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fprintf(fp, "}\n");
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fclose(fp);
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return true;
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}
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bool its_write_obj(const indexed_triangle_set &its, const char *file)
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{
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FILE *fp = boost::nowide::fopen(file, "w");
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if (fp == nullptr) {
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BOOST_LOG_TRIVIAL(error) << "stl_write_obj: Couldn't open " << file << " for writing";
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return false;
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}
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for (size_t i = 0; i < its.vertices.size(); ++ i)
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fprintf(fp, "v %f %f %f\n", its.vertices[i](0), its.vertices[i](1), its.vertices[i](2));
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for (size_t i = 0; i < its.indices.size(); ++ i)
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fprintf(fp, "f %d %d %d\n", its.indices[i][0]+1, its.indices[i][1]+1, its.indices[i][2]+1);
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fclose(fp);
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return true;
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}
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// Check validity of the mesh, assert on error.
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bool stl_validate(const stl_file *stl, const indexed_triangle_set &its)
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{
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assert(! stl->facet_start.empty());
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assert(stl->facet_start.size() == stl->stats.number_of_facets);
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assert(stl->neighbors_start.size() == stl->stats.number_of_facets);
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assert(stl->facet_start.size() == stl->neighbors_start.size());
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assert(! stl->neighbors_start.empty());
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assert((its.indices.empty()) == (its.vertices.empty()));
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assert(stl->stats.number_of_facets > 0);
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assert(its.vertices.empty() || its.indices.size() == stl->stats.number_of_facets);
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#ifdef _DEBUG
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// Verify validity of neighborship data.
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for (int facet_idx = 0; facet_idx < (int)stl->stats.number_of_facets; ++ facet_idx) {
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const stl_neighbors &nbr = stl->neighbors_start[facet_idx];
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const int *vertices = its.indices.empty() ? nullptr : its.indices[facet_idx].data();
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for (int nbr_idx = 0; nbr_idx < 3; ++ nbr_idx) {
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int nbr_face = stl->neighbors_start[facet_idx].neighbor[nbr_idx];
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assert(nbr_face < (int)stl->stats.number_of_facets);
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if (nbr_face != -1) {
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int nbr_vnot = nbr.which_vertex_not[nbr_idx];
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assert(nbr_vnot >= 0 && nbr_vnot < 6);
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// Neighbor of the neighbor is the original face.
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assert(stl->neighbors_start[nbr_face].neighbor[(nbr_vnot + 1) % 3] == facet_idx);
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int vnot_back = stl->neighbors_start[nbr_face].which_vertex_not[(nbr_vnot + 1) % 3];
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assert(vnot_back >= 0 && vnot_back < 6);
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assert((nbr_vnot < 3) == (vnot_back < 3));
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assert(vnot_back % 3 == (nbr_idx + 2) % 3);
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if (vertices != nullptr) {
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// Has shared vertices.
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if (nbr_vnot < 3) {
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// Faces facet_idx and nbr_face share two vertices accross the common edge. Faces are correctly oriented.
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assert((its.indices[nbr_face][(nbr_vnot + 1) % 3] == vertices[(nbr_idx + 1) % 3] && its.indices[nbr_face][(nbr_vnot + 2) % 3] == vertices[nbr_idx]));
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} else {
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// Faces facet_idx and nbr_face share two vertices accross the common edge. Faces are incorrectly oriented, one of them is flipped.
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assert((its.indices[nbr_face][(nbr_vnot + 2) % 3] == vertices[(nbr_idx + 1) % 3] && its.indices[nbr_face][(nbr_vnot + 1) % 3] == vertices[nbr_idx]));
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}
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}
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}
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}
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}
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#endif /* _DEBUG */
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return true;
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}
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// Check validity of the mesh, assert on error.
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bool stl_validate(const stl_file *stl)
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{
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indexed_triangle_set its;
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return stl_validate(stl, its);
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}
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