fix:

1. special format of obj file(with only 1 F term)
2. Grid sample under too small area

src/API/MSGrid.cpp

@@ -85,8 +85,8 @@ void MSGrid::generateSamplesInternal(Array<Surface::Point> *pts, int numSamples,
     //  get normal
     Vector3D n;
     sur.getTriangleNormal(&n, i);
-
-    if (num > 1) {
+    float tArea = areaTriangle(p[0], p[1], p[2]);
+    if (num > 1 && tArea >= 1e-6) {
       //  generate random samples on the triangle
       Array<Point3D> points;
       sampleTriangleGrid(&points, num, p);
@@ -98,7 +98,7 @@ void MSGrid::generateSamplesInternal(Array<Surface::Point> *pts, int numSamples,
         p->p = points.index(j);
         p->n = n;
       }
-    } else /*if (num == 1)*/ {
+    } else /*if (num == 1 || tArea < 1e-6)*/ {
       //  should we use incenter ??
       Surface::Point *s = &pts->addItem();
       s->n = n;

src/Surface/OBJLoader.cpp

@@ -88,8 +88,10 @@ bool loadOBJ(Surface *sur, const char *fileName, float boxSize) {
 
         //  decode token
         int a = 0, b = 0, c = 0;
-        if (token == NULL || (sscanf(token, "%d/%d/%d", &a, &b, &c) != 3 &&
-                              sscanf(token, "%d//%d", &a, &c) != 2)) {
+        if (token == NULL ||
+            (sscanf(token, "%d/%d/%d", &a, &b, &c) != 3  &&
+             sscanf(token, "%d//%d", &a, &c) != 2 &&
+             sscanf(token, "%d", &a) != 1)){
           fclose(f);
           return false;
         }