Incorrect error handling of invalid polygons. about poly2tri HOT 9 CLOSED

C++ version BTW.

Currently the lib assumes that the user has validated the input to be a simple 
polygon.

I'm looking into a way to just throw an exception in cases where constraints 
intersect during the triangulation.

I believe the C# port has some excellent pre-processing functions to help 
simplify the initialization/validation process. I'm in the process of updating 
the C++ code, and will incorporate into the library soon.

Sorry I completely forgot about this issue, have been busy with other stuff.

My first brain storm on this would be the following:
To throw an exception when we have intersecting constraints this should be all 
we need to do. (Not tested)

When enforcing a constraint on the triangulation we trace the constraint thru 
current triangulation and flip triangles. We could easily test if one of the 
edges we cross already are a constrained edge and throw an exception.

I would implement this as follows:
In void Sweep::FlipEdgeEvent(..)
Adding this as first thing to do in that method

    if( t.getConstrainedEdgeAcross(p) )
    {
        throw new RuntimeException( "Input Error: Intersecting Constraints" );
    }

should be enough to catch all constraint intersections due to self intersecting 
input.

with a reservation for not having tested it yet :)

There is no such method in the Triangle class as we speak.
The only 2 I can see are:

- bool GetConstrainedEdgeCCW(Point& p);
- bool GetConstrainedEdgeCW(Point& p);

Oh. sorry. I'm working with the Java version so didn't know that.

    public boolean getConstrainedEdgeAcross( TriangulationPoint p )
    {
        if( p == points[0] )
        {
            return cEdge[0];
        }
        else if( p == points[1] )
        {
            return cEdge[1];
        }
        return cEdge[2];
    }

Seems to work like a charm, thanks!