diff --git a/example/CMakeLists.txt b/example/CMakeLists.txt
index e338d8f..4566857 100644
--- a/example/CMakeLists.txt
+++ b/example/CMakeLists.txt
@@ -23,7 +23,7 @@ add_example(windowfunc_ex OFF)
add_example(legendre_ex OFF)
add_example(refellipsoid_ex OFF)
add_example(kde_ex OFF)
-add_example(meshio_ex ON)
+add_example(meshio_ex OFF)
add_example(autodiff_ex OFF)
add_example(multinary_ex OFF)
add_example(text_io_ex OFF)
@@ -31,4 +31,5 @@ add_example(getoption_ex OFF)
add_example(process_ex OFF)
add_example(array_ex OFF)
add_example(gmt_ex OFF)
-add_example(gnuplot_ex OFF)
\ No newline at end of file
+add_example(gnuplot_ex OFF)
+add_example(stl_io_ex OFF)
\ No newline at end of file
diff --git a/example/stl_io_ex.cpp b/example/stl_io_ex.cpp
new file mode 100644
index 0000000..b433f36
--- /dev/null
+++ b/example/stl_io_ex.cpp
@@ -0,0 +1,50 @@
+/********************************************************
+ * ██████╗ ██████╗████████╗██╗
+ * ██╔════╝ ██╔════╝╚══██╔══╝██║
+ * ██║ ███╗██║ ██║ ██║
+ * ██║ ██║██║ ██║ ██║
+ * ╚██████╔╝╚██████╗ ██║ ███████╗
+ * ╚═════╝ ╚═════╝ ╚═╝ ╚══════╝
+ * Geophysical Computational Tools & Library (GCTL)
+ *
+ * Copyright (c) 2023 Yi Zhang (yizhang-geo@zju.edu.cn)
+ *
+ * GCTL is distributed under a dual licensing scheme. You can redistribute
+ * it and/or modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, either version 2
+ * of the License, or (at your option) any later version. You should have
+ * received a copy of the GNU Lesser General Public License along with this
+ * program. If not, see .
+ *
+ * If the terms and conditions of the LGPL v.2. would prevent you from using
+ * the GCTL, please consider the option to obtain a commercial license for a
+ * fee. These licenses are offered by the GCTL's original author. As a rule,
+ * licenses are provided "as-is", unlimited in time for a one time fee. Please
+ * send corresponding requests to: yizhang-geo@zju.edu.cn. Please do not forget
+ * to include some description of your company and the realm of its activities.
+ * Also add information on how to contact you by electronic and paper mail.
+ ******************************************************/
+
+#include "../lib/core.h"
+#include "../lib/io.h"
+
+using namespace gctl;
+
+int main(int argc, char const *argv[]) try
+{
+ array nodes;
+ array tris;
+ read_stl_ascii("tmp/Stanford_Bunny", nodes, tris);
+
+ mesh_io mshio;
+ mshio.import_from(tris, nodes);
+ mshio.save_gmsh_v2_ascii("tmp");
+ mshio.info();
+
+ save_stl_ascii("tmp", nodes, tris, "Stanford_Bunny");
+ return 0;
+}
+catch(std::exception &e)
+{
+ GCTL_ShowWhatError(e.what(), GCTL_ERROR_ERROR, 0, 0, 0);
+}
\ No newline at end of file
diff --git a/lib/io.h b/lib/io.h
index 3e5b4c6..40b9e7b 100644
--- a/lib/io.h
+++ b/lib/io.h
@@ -38,5 +38,6 @@
#include "io/tetgen_io.h"
#include "io/triangle_io.h"
#include "io/off_io.h"
+#include "io/stl_io.h"
#endif // _GCTL_IO_H
\ No newline at end of file
diff --git a/lib/io/stl_io.h b/lib/io/stl_io.h
new file mode 100644
index 0000000..c1c3a28
--- /dev/null
+++ b/lib/io/stl_io.h
@@ -0,0 +1,158 @@
+/********************************************************
+ * ██████╗ ██████╗████████╗██╗
+ * ██╔════╝ ██╔════╝╚══██╔══╝██║
+ * ██║ ███╗██║ ██║ ██║
+ * ██║ ██║██║ ██║ ██║
+ * ╚██████╔╝╚██████╗ ██║ ███████╗
+ * ╚═════╝ ╚═════╝ ╚═╝ ╚══════╝
+ * Geophysical Computational Tools & Library (GCTL)
+ *
+ * Copyright (c) 2023 Yi Zhang (yizhang-geo@zju.edu.cn)
+ *
+ * GCTL is distributed under a dual licensing scheme. You can redistribute
+ * it and/or modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, either version 2
+ * of the License, or (at your option) any later version. You should have
+ * received a copy of the GNU Lesser General Public License along with this
+ * program. If not, see .
+ *
+ * If the terms and conditions of the LGPL v.2. would prevent you from using
+ * the GCTL, please consider the option to obtain a commercial license for a
+ * fee. These licenses are offered by the GCTL's original author. As a rule,
+ * licenses are provided "as-is", unlimited in time for a one time fee. Please
+ * send corresponding requests to: yizhang-geo@zju.edu.cn. Please do not forget
+ * to include some description of your company and the realm of its activities.
+ * Also add information on how to contact you by electronic and paper mail.
+ ******************************************************/
+
+#ifndef _GCTL_STL_IO_H
+#define _GCTL_STL_IO_H
+
+// library's head file
+#include "../core.h"
+#include "../utility.h"
+#include "../geometry.h"
+
+namespace gctl
+{
+ template
+ void read_stl_ascii(std::string filename, array> &nodes,
+ array> &facets, std::string solid = "null", double eps = 1e-8)
+ {
+ std::ifstream infile;
+ open_infile(infile, filename, ".stl");
+
+ vertex3dc tmp_node;
+ std::vector tmp_nodes;
+ _1i_vector one_tri(3);
+ _2i_vector tmp_tris;
+
+ bool inside_solid, new_node;
+ point3dc nor, vt[3];
+ char solid_name[256], solid_endname[256];
+ std::string line;
+ while (std::getline(infile, line))
+ {
+ if (sscanf(line.c_str(), "solid %s", solid_name) == 1 && (!strcmp(solid_name, solid.c_str()) || solid == "null"))
+ {
+ inside_solid = true;
+ while (inside_solid)
+ {
+ std::getline(infile, line);
+ if (sscanf(line.c_str(), "endsolid %s", solid_endname) == 1)
+ {
+ if (strcmp(solid_endname, solid_name))
+ throw std::runtime_error("[gctl::read_stl_ascii] Invalid solid names.");
+
+ inside_solid = false;
+ }
+ else
+ {
+ sscanf(line.c_str(), "facet normal %lf %lf %lf", &nor.x, &nor.y, &nor.z);
+ std::getline(infile, line); // outer loop
+ for (int i = 0; i < 3; i++)
+ {
+ std::getline(infile, line);
+ line.erase(0, line.find_first_not_of(" \t"));
+ line.erase(line.find_last_not_of(" \t") + 1);
+ sscanf(line.c_str(), "vertex %lf %lf %lf", &vt[i].x, &vt[i].y, &vt[i].z);
+ }
+ std::getline(infile, line); // endloop
+ std::getline(infile, line); // endfacet
+
+ for (size_t i = 0; i < 3; i++)
+ {
+ tmp_node.id = tmp_nodes.size();
+ tmp_node.x = vt[i].x;
+ tmp_node.y = vt[i].y;
+ tmp_node.z = vt[i].z;
+
+ new_node = true;
+ for (size_t v = 0; v < tmp_nodes.size(); v++)
+ {
+ if (isequal(tmp_nodes[v], tmp_node, eps))
+ {
+ tmp_node.id = tmp_nodes[v].id;
+ new_node = false;
+ break;
+ }
+ }
+
+ if (new_node) tmp_nodes.push_back(tmp_node);
+ one_tri[i] = tmp_node.id;
+ }
+ tmp_tris.push_back(one_tri);
+ }
+ }
+ }
+ }
+ infile.close();
+
+ nodes.resize(tmp_nodes.size());
+ for (size_t i = 0; i < tmp_nodes.size(); i++)
+ {
+ nodes[i].id = tmp_nodes[i].id;
+ nodes[i].x = tmp_nodes[i].x;
+ nodes[i].y = tmp_nodes[i].y;
+ nodes[i].z = tmp_nodes[i].z;
+ }
+
+ facets.resize(tmp_tris.size());
+ for (size_t i = 0; i < tmp_tris.size(); i++)
+ {
+ facets[i].set(nodes[tmp_tris[i][0]], nodes[tmp_tris[i][1]], nodes[tmp_tris[i][2]], i);
+ }
+
+ destroy_vector(tmp_nodes);
+ destroy_vector(tmp_tris);
+ destroy_vector(one_tri);
+ return;
+ }
+
+ template
+ void save_stl_ascii(std::string filename, const array> &nodes,
+ const array> &facets, std::string solid)
+ {
+ std::ofstream outfile;
+ open_outfile(outfile, filename, ".stl");
+
+ point3dc nor;
+ outfile << "solid " << solid << "\n";
+ for (size_t i = 0; i < facets.size(); i++)
+ {
+ nor = cross(*facets[i].vert[1] - *facets[i].vert[0], *facets[i].vert[2] - *facets[i].vert[0]).normal();
+ outfile << "facet normal " << nor.x << " " << nor.y << " " << nor.z << "\n";
+ outfile << " outer loop\n";
+ outfile << " vertex " << facets[i].vert[0]->x << " " << facets[i].vert[0]->y << " " << facets[i].vert[0]->z << "\n";
+ outfile << " vertex " << facets[i].vert[1]->x << " " << facets[i].vert[1]->y << " " << facets[i].vert[1]->z << "\n";
+ outfile << " vertex " << facets[i].vert[2]->x << " " << facets[i].vert[2]->y << " " << facets[i].vert[2]->z << "\n";
+ outfile << " endloop\n";
+ outfile << "endfacet\n";
+ }
+ outfile << "endsolid " << solid <<