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gareththegeek's picture

VB.Net Fog is Ambiguous

Posted Thursday, 21 May, 2009 - 19:14 by gareththegeek in

I am unable to use the Fog functions in VB.Net in the head revision because of the following compilation error:

'Fog' is ambiguous because multiple kinds of members with this name exist in class 'OpenTK.Graphics.GL'.

I believe this is an issue with VB.Net and C#.Net interoperability, for example:
http://msdn.microsoft.com/en-us/library/ms235408.aspx

Any ideas?

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the Fiddler's picture

Re: VB.Net Fog is Ambiguous

Posted Thursday, 21 May, 2009 - 21:10 by the Fiddler

The important question here is, which version of OpenTK are you using? Is it 0.9.7 or SVN? This could be an interoperability issue, but not due to case-sensitivity.

Can you post your exact call to the Fog method? The solution could be as simple as a plain cast to the correct type.

Edit: OK, I've managed to reproduce the error. The issue is that VB.Net cannot distinguish between:

     Sub Fog(ByVal pname As FogParameter, ByRef params As Single)
    Sub Fog(ByVal pname As FogParameter, ByVal params As Single)

C# uses the ref keyword which allows the compiler to distinguish between those two.

One solution is to revert the change and use Fogv and Fog to distinguish between the two. I don't know if it is possible to somehow instruct the compiler which method to use. It seems [CLSCompliant(false)] is ignored when consuming the assembly, but there might be another way (reading the docs).

Any ideas?

the Fiddler's picture

Re: VB.Net Fog is Ambiguous

Posted Thursday, 21 May, 2009 - 23:39 by the Fiddler

The issues related to Fog functions should be resolved now (SVN 1763+).

I took the butcher's approach of removing all ambiguous overloads. This is a breaking change, but a) affected code is easy to fix and b) these overloads would be broken during the 0.9.7 -> 0.9.8 transition anyway.

gareththegeek's picture

Re: VB.Net Fog is Ambiguous

Posted Friday, 22 May, 2009 - 15:53 by gareththegeek

You are correct. The issue is because you do not explicitly specify that an argument is by ref when calling a function in VB.Net and worse there IS no way to do so :(

I guess I've just never got on with C syntax, I used to use Pascal!!

Thanks for sorting this out. I will test out the SVN head revision (to replace my hacked about version where I was renaming things back to fogv, texparameterv, &c)

the Fiddler's picture

Re: VB.Net Fog is Ambiguous

Posted Friday, 22 May, 2009 - 16:41 by the Fiddler

Please tell me if you encounter any more problems related to this. If worse comes to worst, it is always possible to revert the change.