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/* ADMesh -- process triangulated solid meshes
* Copyright (C) 1995, 1996 Anthony D. Martin <amartin@engr.csulb.edu>
* Copyright (C) 2013, 2014 several contributors, see AUTHORS
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Questions, comments, suggestions, etc to
* https://github.com/admesh/admesh/issues
*/
#include <stdlib.h>
#include <string.h>
#include <vector>
#include <boost/nowide/cstdio.hpp>
#include "stl.h"
void stl_invalidate_shared_vertices(stl_file *stl)
{
stl->v_indices.clear();
stl->v_shared.clear();
}
void stl_generate_shared_vertices(stl_file *stl)
{
// 3 indices to vertex per face
stl->v_indices.assign(stl->stats.number_of_facets, v_indices_struct());
// Shared vertices (3D coordinates)
stl->v_shared.clear();
stl->v_shared.reserve(stl->stats.number_of_facets / 2);
// A degenerate mesh may contain loops: Traversing a fan will end up in an endless loop
// while never reaching the starting face. To avoid these endless loops, traversed faces at each fan traversal
// are marked with a unique fan_traversal_stamp.
unsigned int fan_traversal_stamp = 0;
std::vector<unsigned int> fan_traversal_facet_visited(stl->stats.number_of_facets, 0);
for (uint32_t facet_idx = 0; facet_idx < stl->stats.number_of_facets; ++ facet_idx) {
for (int j = 0; j < 3; ++ j) {
if (stl->v_indices[facet_idx].vertex[j] != -1)
// Shared vertex was already assigned.
continue;
// Create a new shared vertex.
stl->v_shared.emplace_back(stl->facet_start[facet_idx].vertex[j]);
// 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.
int facet_in_fan_idx = facet_idx;
bool edge_direction = false;
bool traversal_reversed = false;
int vnot = (j + 2) % 3;
// Increase the
++ fan_traversal_stamp;
for (;;) {
// Next edge on facet_in_fan_idx to be traversed. The edge is indexed by its starting vertex index.
int next_edge = 0;
// Vertex index in facet_in_fan_idx, which is being pivoted around, and which is being assigned a new shared vertex.
int pivot_vertex = 0;
if (vnot > 2) {
// The edge of facet_in_fan_idx opposite to vnot is equally oriented, therefore
// the neighboring facet is flipped.
if (! edge_direction) {
pivot_vertex = (vnot + 2) % 3;
next_edge = pivot_vertex;
} else {
pivot_vertex = (vnot + 1) % 3;
next_edge = vnot % 3;
}
edge_direction = ! edge_direction;
} else {
// The neighboring facet is correctly oriented.
if (! edge_direction) {
pivot_vertex = (vnot + 1) % 3;
next_edge = vnot;
} else {
pivot_vertex = (vnot + 2) % 3;
next_edge = pivot_vertex;
}
}
stl->v_indices[facet_in_fan_idx].vertex[pivot_vertex] = stl->v_shared.size() - 1;
fan_traversal_facet_visited[facet_in_fan_idx] = fan_traversal_stamp;
// next_edge is an index of the starting vertex of the edge, not an index of the opposite vertex to the edge!
int next_facet = stl->neighbors_start[facet_in_fan_idx].neighbor[next_edge];
if (next_facet == -1) {
// No neighbor going in the current direction.
if (traversal_reversed) {
// Went to one limit, then turned back and reached the other limit. Quit the fan traversal.
break;
} else {
// Reached the first limit. Now try to reverse and traverse up to the other limit.
edge_direction = true;
vnot = (j + 1) % 3;
traversal_reversed = true;
facet_in_fan_idx = facet_idx;
}
} else if (next_facet == facet_idx) {
// Traversed a closed fan all around.
// assert(! traversal_reversed);
break;
} else if (next_facet >= (int)stl->stats.number_of_facets) {
// The mesh is not valid!
// assert(false);
break;
} else if (fan_traversal_facet_visited[next_facet] == fan_traversal_stamp) {
// Traversed a closed fan all around, but did not reach the starting face.
// This indicates an invalid geometry (non-manifold).
//assert(false);
break;
} else {
// Continue traversal.
// next_edge is an index of the starting vertex of the edge, not an index of the opposite vertex to the edge!
vnot = stl->neighbors_start[facet_in_fan_idx].which_vertex_not[next_edge];
facet_in_fan_idx = next_facet;
}
}
}
}
}
bool stl_write_off(stl_file *stl, const char *file)
{
/* Open the file */
FILE *fp = boost::nowide::fopen(file, "w");
if (fp == nullptr) {
char *error_msg = (char*)malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing", file);
perror(error_msg);
free(error_msg);
return false;
}
fprintf(fp, "OFF\n");
fprintf(fp, "%d %d 0\n", stl->v_shared.size(), stl->stats.number_of_facets);
for (int i = 0; i < stl->v_shared.size(); ++ i)
fprintf(fp, "\t%f %f %f\n", stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
fprintf(fp, "\t3 %d %d %d\n", stl->v_indices[i].vertex[0], stl->v_indices[i].vertex[1], stl->v_indices[i].vertex[2]);
fclose(fp);
return true;
}
bool stl_write_vrml(stl_file *stl, const char *file)
{
/* Open the file */
FILE *fp = boost::nowide::fopen(file, "w");
if (fp == nullptr) {
char *error_msg = (char*)malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing", file);
perror(error_msg);
free(error_msg);
return false;
}
fprintf(fp, "#VRML V1.0 ascii\n\n");
fprintf(fp, "Separator {\n");
fprintf(fp, "\tDEF STLShape ShapeHints {\n");
fprintf(fp, "\t\tvertexOrdering COUNTERCLOCKWISE\n");
fprintf(fp, "\t\tfaceType CONVEX\n");
fprintf(fp, "\t\tshapeType SOLID\n");
fprintf(fp, "\t\tcreaseAngle 0.0\n");
fprintf(fp, "\t}\n");
fprintf(fp, "\tDEF STLModel Separator {\n");
fprintf(fp, "\t\tDEF STLColor Material {\n");
fprintf(fp, "\t\t\temissiveColor 0.700000 0.700000 0.000000\n");
fprintf(fp, "\t\t}\n");
fprintf(fp, "\t\tDEF STLVertices Coordinate3 {\n");
fprintf(fp, "\t\t\tpoint [\n");
int i = 0;
for (; i + 1 < stl->v_shared.size(); ++ i)
fprintf(fp, "\t\t\t\t%f %f %f,\n", stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
fprintf(fp, "\t\t\t\t%f %f %f]\n", stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
fprintf(fp, "\t\t}\n");
fprintf(fp, "\t\tDEF STLTriangles IndexedFaceSet {\n");
fprintf(fp, "\t\t\tcoordIndex [\n");
for (int i = 0; i + 1 < (int)stl->stats.number_of_facets; ++ i)
fprintf(fp, "\t\t\t\t%d, %d, %d, -1,\n", stl->v_indices[i].vertex[0], stl->v_indices[i].vertex[1], stl->v_indices[i].vertex[2]);
fprintf(fp, "\t\t\t\t%d, %d, %d, -1]\n", stl->v_indices[i].vertex[0], stl->v_indices[i].vertex[1], stl->v_indices[i].vertex[2]);
fprintf(fp, "\t\t}\n");
fprintf(fp, "\t}\n");
fprintf(fp, "}\n");
fclose(fp);
return true;
}
bool stl_write_obj(stl_file *stl, const char *file)
{
FILE *fp = boost::nowide::fopen(file, "w");
if (fp == nullptr) {
char* error_msg = (char*)malloc(81 + strlen(file)); /* Allow 80 chars+file size for message */
sprintf(error_msg, "stl_write_ascii: Couldn't open %s for writing", file);
perror(error_msg);
free(error_msg);
return false;
}
for (size_t i = 0; i < stl->v_shared.size(); ++ i)
fprintf(fp, "v %f %f %f\n", stl->v_shared[i](0), stl->v_shared[i](1), stl->v_shared[i](2));
for (uint32_t i = 0; i < stl->stats.number_of_facets; ++ i)
fprintf(fp, "f %d %d %d\n", stl->v_indices[i].vertex[0]+1, stl->v_indices[i].vertex[1]+1, stl->v_indices[i].vertex[2]+1);
fclose(fp);
return true;
}
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