Is there a limit/restriction on the s2polygon size?

[sreekanth-cb]

Hi @jmr,

Can you please help me with another doubt around the s2 polygon.

Having trouble understanding the problem reported here - golang/geo#78
And I tried to replicate the same test here.

Looks like the test is timing out against C++ version.
We can see that the original/first polygon is really large covering almost the entire sphere.

Is this stem out from any known restriction or limitation here?

TEST(S2NonOverlapping1, AllCases) {
  vector<S2Point> pts(5);
  S2LatLng latlng;
  
  pts[0] = latlng.FromDegrees(-38.0, -135.0).ToPoint();
  pts[1] = latlng.FromDegrees(-38.0, 149.0).ToPoint();
  pts[2] = latlng.FromDegrees(77.0, 149.0).ToPoint();
  pts[3] = latlng.FromDegrees(77.0, -135.0).ToPoint();
  pts[4] = latlng.FromDegrees(-38.0, -135.0).ToPoint();
  
  vector<std::unique_ptr<S2Loop>> loops;
  loops.emplace_back(new S2Loop(pts));  
  S2Polygon polygon1 = S2Polygon(std::move(loops));

  pts.clear();
  pts.resize(5);
  pts[0] = latlng.FromDegrees(37.99616267972809, 13.007812500000002).ToPoint();
  pts[1] = latlng.FromDegrees(7.99616267972809, 13.359375000000002).ToPoint();
  pts[2] = latlng.FromDegrees(38.272819658516866, 13.359375000000002).ToPoint();
  pts[3] = latlng.FromDegrees(38.272819658516866, 13.007812500000002).ToPoint();
  pts[4] = latlng.FromDegrees(37.99616267972809, 13.007812500000002).ToPoint();

 
  loops.clear();
  loops.emplace_back(new S2Loop(pts));  

  auto polygon2 = S2Polygon(std::move(loops));

  bool contains = polygon1.Contains(&polygon2);
  EXPECT_EQ(false,contains); 

  pts.clear();
  pts.resize(5);
  pts[0] = latlng.FromDegrees(37.99616267972809, 13.007812500000002).ToPoint();
  pts[1] = latlng.FromDegrees(7.99616267972809, 13.559375000000002).ToPoint();
  pts[2] = latlng.FromDegrees(38.472819658516866, 13.559375000000002).ToPoint();
  pts[3] = latlng.FromDegrees(38.472819658516866, 13.007812500000002).ToPoint();
  pts[4] = latlng.FromDegrees(37.99616267972809, 13.007812500000002).ToPoint();

 
  loops.clear();
  loops.emplace_back(new S2Loop(pts));  

  auto polygon3 = S2Polygon(std::move(loops));
  bool contains = polygon1.Contains(&polygon3);
  EXPECT_EQ(false,contains); 
}

[jmr]

The first vertex of an S2Loop is already implicitly connected to the last:

s2geometry/src/s2/s2loop.h

Line 60 in ae470b7

// chain of vertices where the first vertex is implicitly connected to the

Duplicate vertices are not allowed:

s2geometry/src/s2/s2loop.h

Line 66 in ae470b7

// Loops are not allowed to have any duplicate vertices (whether adjacent or

You will see errors logged if you configured with glog. Debug mode should also CHECK-fail that the loop isn't valid.