TopoDS_Shape as a map key? - Forum Open Cascade Technology

wayne606
Mon, 07/25/2011 - 22:37

Forums:

I have code that looks like:

std::map shmap;
shmap[myshape] = "have a nice day";

but I get a compilation error:

/usr/include/c++/4.5/bits/stl_function.h:230:22: error: no match for 'operator

Is there a way to use a TopoDS_Shape as a stl::map key? Alternately, is there a way I can get a unique id (string, int, whatever) from a shape that I can use in this way?

Thanks,

Wayne

haowei
Tue, 07/26/2011 - 05:25

try TopoDS_Shape::HashCode

wayne606
Tue, 07/26/2011 - 17:57

The problem with HashCode is that a hash is not one-to-one - multiple shapes could have the same hash code.

I ended up solving this by creating my own shape -> unique id map using TopTools_IndexedMapOfShape and then using this as a key to the map.

I think a few additions to the shape class would make it possible to use it as a key in maps. The > operation could be based on the address of the underlying TShape (which is invariant, correct?) and the address and orientation fields.

Bearloga
Tue, 07/26/2011 - 18:13

Why you do not use NCollection_DataMap template class?

NCollection_DataMap shmap;
shmap.Bind(myshape, "have a nice day");

For that, define the following global methods:
inline Standard_Boolean IsEqual(const TopoDS_Shape& s1, const TopoDS_Shape& s2)
{
s1 == s2;
}
inline int HashCode(const TopoDS_Shape& s, int u)
{
return s.HashCode(u);
}

wayne606
Tue, 07/26/2011 - 18:36

Ah, that would have saved me some effort... It's so hard to find stuff in OpenCascade... Thanks...