bool read_obj(Surface_mesh& mesh, const std::string& filename)
{
char s[200];
float x, y, z;
std::vector<Surface_mesh::Vertex> vertices;
std::vector<Texture_coordinate> all_tex_coords; //individual texture coordinates
std::vector<int> halfedge_tex_idx; //texture coordinates sorted for halfedges
Surface_mesh::Halfedge_property <Texture_coordinate> tex_coords = mesh.halfedge_property<Texture_coordinate>("h:texcoord");
bool with_tex_coord=false;
// clear mesh
mesh.clear();
// open file (in ASCII mode)
FILE* in = fopen(filename.c_str(), "r");
if (!in) return false;
// clear line once
memset(&s, 0, 200);
// parse line by line (currently only supports vertex positions & faces
while(in && !feof(in) && fgets(s, 200, in))
{
// comment
if (s[0] == '#' || isspace(s[0])) continue;
// vertex
else if (strncmp(s, "v ", 2) == 0)
{
if (sscanf(s, "v %f %f %f", &x, &y, &z))
{
mesh.add_vertex(Point(x,y,z));
}
}
// normal
else if (strncmp(s, "vn ", 3) == 0)
{
if (sscanf(s, "vn %f %f %f", &x, &y, &z))
{
// problematic as it can be either a vertex property when interpolated
// or a halfedge property for hard edges
}
}
// texture coordinate
else if (strncmp(s, "vt ", 3) == 0)
{
if (sscanf(s, "vt %f %f", &x, &y))
{
z=1;
all_tex_coords.push_back(Texture_coordinate(x,y,z));
}
}
// face
else if (strncmp(s, "f ", 2) == 0)
{
int component(0), nV(0);
bool endOfVertex(false);
char *p0, *p1(s+1);
vertices.clear();
halfedge_tex_idx.clear();
// skip white-spaces
while (*p1==' ') ++p1;
while (p1)
{
p0 = p1;
// overwrite next separator
// skip '/', '\n', ' ', '\0', '\r' <-- don't forget Windows
while (*p1!='/' && *p1!='\r' && *p1!='\n' && *p1!=' ' && *p1!='\0') ++p1;
// detect end of vertex
if (*p1 != '/')
{
endOfVertex = true;
}
// replace separator by '\0'
if (*p1 != '\0')
{
*p1 = '\0';
p1++; // point to next token
}
// detect end of line and break
if (*p1 == '\0' || *p1 == '\n')
{
p1 = 0;
}
// read next vertex component
if (*p0 != '\0')
{
switch (component)
{
case 0: // vertex
{
vertices.push_back( Surface_mesh::Vertex(atoi(p0) - 1) );
break;
}
case 1: // texture coord
{
int idx = atoi(p0)-1;
halfedge_tex_idx.push_back(idx);
with_tex_coord=true;
break;
}
case 2: // normal
break;
}
}
++component;
if (endOfVertex)
{
component = 0;
nV++;
endOfVertex = false;
}
}
Surface_mesh::Face f=mesh.add_face(vertices);
// add texture coordinates
if(with_tex_coord)
{
Surface_mesh::Halfedge_around_face_circulator h_fit = mesh.halfedges(f);
Surface_mesh::Halfedge_around_face_circulator h_end = h_fit;
unsigned v_idx =0;
do
{
tex_coords[*h_fit]=all_tex_coords.at(halfedge_tex_idx.at(v_idx));
++v_idx;
++h_fit;
}
while(h_fit!=h_end);
}
}
// clear line
memset(&s, 0, 200);
}
fclose(in);
return true;
}
bool write_obj(const Surface_mesh& mesh, const std::string& filename)
{
FILE* out = fopen(filename.c_str(), "w");
if (!out)
return false;
// comment
fprintf(out, "# OBJ export from Surface_mesh\n");
//vertices
Surface_mesh::Vertex_property<Point> points = mesh.get_vertex_property<Point>("v:point");
for (Surface_mesh::Vertex_iterator vit=mesh.vertices_begin(); vit!=mesh.vertices_end(); ++vit)
{
const Point& p = points[*vit];
fprintf(out, "v %.10f %.10f %.10f\n", p[0], p[1], p[2]);
}
//normals
Surface_mesh::Vertex_property<Point> normals = mesh.get_vertex_property<Point>("v:normal");
for (Surface_mesh::Vertex_iterator vit=mesh.vertices_begin(); vit!=mesh.vertices_end(); ++vit)
{
const Point& p = normals[*vit];
fprintf(out, "vn %.10f %.10f %.10f\n", p[0], p[1], p[2]);
}
//optionally texture coordinates
// do we have them?
std::vector<std::string> h_props= mesh.halfedge_properties();
bool with_tex_coord = false;
std::vector<std::string>::iterator h_prop_end = h_props.end();
std::vector<std::string>::iterator h_prop_start= h_props.begin();
while(h_prop_start!=h_prop_end)
{
if(0==(*h_prop_start).compare("h:texcoord"))
{
with_tex_coord=true;
}
++h_prop_start;
}
//if so then add
if(with_tex_coord)
{
Surface_mesh::Halfedge_property<Texture_coordinate> tex_coord = mesh.get_halfedge_property<Texture_coordinate>("h:texcoord");
for (Surface_mesh::Halfedge_iterator hit=mesh.halfedges_begin(); hit!=mesh.halfedges_end(); ++hit)
{
const Texture_coordinate& pt = tex_coord[*hit];
fprintf(out, "vt %.10f %.10f %.10f\n", pt[0], pt[1], pt[2]);
}
}
//faces
for (Surface_mesh::Face_iterator fit=mesh.faces_begin(); fit!=mesh.faces_end(); ++fit)
{
fprintf(out, "f");
Surface_mesh::Vertex_around_face_circulator fvit=mesh.vertices(*fit), fvend=fvit;
Surface_mesh::Halfedge_around_face_circulator fhit=mesh.halfedges(*fit);
do
{
if(with_tex_coord)
{
// write vertex index, tex_coord index and normal index
fprintf(out, " %d/%d/%d", (*fvit).idx()+1, (*fhit).idx()+1, (*fvit).idx()+1);
++fhit;
}
else
{
// write vertex index and normal index
fprintf(out, " %d//%d", (*fvit).idx()+1, (*fvit).idx()+1);
}
}
while (++fvit != fvend);
fprintf(out, "\n");
}
fclose(out);
return true;
}
