Merge pull request #2657 from afabri/Polyhedron_IO-improve_read_STL-GF

Parse headers of binary STL files starting with the keyword 'solid' correctly as binary STL

Polyhedron_IO/include/CGAL/IO/STL_reader.h

@@ -26,6 +26,7 @@
 #include <map>
 #include <iostream>
 #include <string>
+#include <cctype>
 
 namespace CGAL{
 
@@ -35,26 +36,97 @@ namespace CGAL{
             std::vector< cpp11::array<int,3> >& facets,
             bool verbose = false)
   {
-    std::string s, solid("solid");
+    bool is_binary_file = false;
+    
+    std::string s, solid("solid"), facet("facet");
     std::map<cpp11::array<double,3>, int> pmap;
     int index = 0;
     cpp11::array<int,3> ijk;
     cpp11::array<double,3> p;
 
     char line[80];
-    for(int i=0;i < 80; i++){
-      boost::uint8_t c;
-      input.read(reinterpret_cast<char*>(&c), sizeof(c));
-      line[i]=c;
-      if(i==5){
-        s = std::string(line,5);
-        if(s == solid){
-          break;
-        }
-      }
-    }
+    int i = 0, ni = 0;
 
-    if(s!= solid){
+      boost::uint8_t c;
+      for(; i < 5; i++){
+        input.read(reinterpret_cast<char*>(&c), sizeof(c));
+        line[i]=c;
+      }
+
+      s = std::string(line,5);
+      if(s == solid){
+        // we found the keyword "solid" which is supposed to indicate the file is Ascii
+        // But it might still be binary, so we have to find out if it is followed
+        // by an (optional) name and then the keyword "facet"
+        // When we find "facet" we conclude that it is really Ascii
+        do {
+          input.read(reinterpret_cast<char*>(&c), sizeof(c));
+          line[i++]=c;
+        }while(isspace(c) && ( i < 80));
+        if(i==80){
+          is_binary_file = true;
+          goto done;
+        }
+        // now c is not whitespace
+        ni = i-1; // here starts either the name or the keyword "facet"
+        do {
+          input.read(reinterpret_cast<char*>(&c), sizeof(c));
+          line[i++]=c;
+        }while(! isspace(c) && ( i < 80));
+        s = std::string(line+ni, (i-1) - ni);
+#       ifdef CGAL_DEBUG_BINARY_HEADER
+          std::cout << "|" << s  << "|" << std::endl;
+#       endif        
+        if(s == facet){
+          goto done;
+        } else if(i == 80){
+          // the entire header is a name
+          is_binary_file = true;
+          goto done;
+        }
+        
+        // we continue to read what comes after the name
+        
+        // now c is whitespace
+        do {
+          input.read(reinterpret_cast<char*>(&c), sizeof(c));
+          line[i++]=c;
+        }while(isspace(c) && ( i < 80));
+        if(i==80){
+          is_binary_file = true;
+          goto done;
+        }
+        
+        // now c is not whitespace
+        ni = i-1; // here starts either "facet", or it is really binary
+        do {
+          input.read(reinterpret_cast<char*>(&c), sizeof(c));
+          line[i++]=c;
+        }while(! isspace(c) && ( i < 80));
+#       ifdef CGAL_DEBUG_BINARY_HEADER
+          s = std::string(line+ni, (i-1) - ni);
+          std::cout << "|" << s  << "|" << std::endl;
+#       endif
+        if(s == facet){
+          goto done;
+        } else {
+          for(; i < 80; i++){
+            input.read(reinterpret_cast<char*>(&c), sizeof(c));
+          }
+          is_binary_file = true;
+          goto done;
+        }
+      }else{
+        // we read the other 75 characters of the header
+        for(; i < 80; i++){
+          input.read(reinterpret_cast<char*>(&c), sizeof(c));
+        }
+        is_binary_file = true;
+      }
+
+  done:
+
+    if(is_binary_file){
       boost::uint32_t N32;
       input.read(reinterpret_cast<char*>(&N32), sizeof(N32));
       unsigned int N = N32;
@@ -96,14 +168,17 @@ namespace CGAL{
       }
       return true;
     } else {
-      std::string facet("facet"),
-        outer("outer"),
+
+      // It is an Ascii file but the first occurence of "facet" has already be parsed
+      bool first_facet = true;
+      std::string outer("outer"),
         loop("loop"),
         vertex("vertex"),
         endloop("endloop"),
         endsolid("endsolid");
-
-      while(input >> s){
+      s = facet;
+      while(first_facet || (input >> s)){
+        first_facet = false;
         if(s == endsolid){
           //std::cerr << "found endsolid" << std::endl;
         } else if(s == facet){

Polyhedron_IO/test/Polyhedron_IO/data/ascii-tetrahedron.stl

@@ -0,0 +1,31 @@
+solid cube_corner
+          facet normal 0.0 -1.0 0.0
+            outer loop
+              vertex 0.0 0.0 0.0
+              vertex 1.0 0.0 0.0
+              vertex 0.0 0.0 1.0
+            endloop
+          endfacet
+          facet normal 0.0 0.0 -1.0
+            outer loop
+              vertex 0.0 0.0 0.0
+              vertex 0.0 1.0 0.0
+              vertex 1.0 0.0 0.0
+            endloop
+          endfacet
+          facet normal -1.0 0.0 0.0
+            outer loop
+              vertex 0.0 0.0 0.0
+              vertex 0.0 0.0 1.0
+              vertex 0.0 1.0 0.0
+            endloop
+          endfacet
+          facet normal 0.577 0.577 0.577
+            outer loop
+              vertex 1.0 0.0 0.0
+              vertex 0.0 1.0 0.0
+              vertex 0.0 0.0 1.0
+            endloop
+          endfacet
+        endsolid
+        

Polyhedron_IO/test/Polyhedron_IO/stl2off.cpp

@@ -1,3 +1,4 @@
+#include <cassert>
 #include <CGAL/IO/STL_reader.h>
 #include <CGAL/array.h>
 
@@ -5,8 +6,9 @@
 #include <iostream>
 #include <vector>
 
-void read(const char* fname)
+void read(const char* fname, std::size_t v, std::size_t f)
 {
+  std::cout << "Reading "<< fname << std::endl;
   std::ifstream input(fname, std::ios::in | std::ios::binary);
 
   std::vector< CGAL::cpp11::array<double,3> > points;
@@ -16,7 +18,10 @@ void read(const char* fname)
                   points,
                   faces,
                   true);
-  
+
+  assert(points.size() == v);
+    assert(faces.size() == f);
+    
   std::cout << "OFF version of file " << fname << std::endl;
 
   std::cout.precision(17);
@@ -35,7 +40,15 @@ void read(const char* fname)
 
 int main()
 {
-  read("data/cube.stl");
-  read("data/triangle.stl");
+  read("data/cube.stl", 8, 12);
+  read("data/triangle.stl", 3, 1);
+
+  
+  read("data/binary-tetrahedron-nice-header.stl", 4, 4);
+  read("data/binary-tetrahedron-non-standard-header-1.stl", 4, 4);
+  read("data/binary-tetrahedron-non-standard-header-2.stl", 4, 4);
+  read("data/binary-tetrahedron-non-standard-header-3.stl", 4, 4);
+  read("data/binary-tetrahedron-non-standard-header-4.stl", 4, 4);
+  read("data/binary-tetrahedron-non-standard-header-5.stl", 4, 4);
   return 0;
 }