Hi Robert,
It's not a small set of changes. It's actually quite tedious (but not complex
to do). Unfortunately, we cannot be sure it avoids the invalid code generation
bug in all cases.
Basically, changing the operator (in this case, it's operator -) from:
/** Binary vector subtract. */
inline const Vec3f operator - (const Vec3f& rhs) const
{
return Vec3f(_v[0]-rhs._v[0], _v[1]-rhs._v[1], _v[2]-rhs._v[2]);
}
/** Unary vector subtract. */
inline Vec3f& operator -= (const Vec3f& rhs)
{
_v[0]-=rhs._v[0];
_v[1]-=rhs._v[1];
_v[2]-=rhs._v[2];
return *this;
}
To:
inline Vec3f & operator -= (const Vec3f& rhs)
{
_v[0] -= rhs._v[0];
_v[1] -= rhs._v[1];
_v[2] -= rhs._v[2];
return *this;
}
inline friend Vec3f operator - (const Vec3f& lhs, const Vec3f& rhs)
{
return Vec3f(lhs) -= rhs;
}
Seems to work around the problem with VS2005 and VS2008 without requiring
changes in the user code. Also, someone's pointed out the latter is more
correct in some cases (e.g. argument dependent lookup, see below).
But changing all the operators of classes like Vec3f, Vec3d (and I suppose
others such as Matrix classes) would be quite tedious. I guess it really
depends on how many people are really by this problem.
One a broader note, I've noticed Boost has a very nice library for dealing with
this (http://www.boost.org/doc/libs/1_37_0/libs/utility/operators.htm). Too bad
OSG probably cannot use it because of the dependencies it would introduce. But
it's still worth a read, as they explain several issues that may not be obvious
at first sight.
Cheers,
Tanguy
-----Original Message-----
From: osg-users-boun...@lists.openscenegraph.org
[mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Robert Osfield
Sent: Wednesday 04 February 2009 12:40
To: OpenSceneGraph Users
Subject: Spam: Re: [osg-users] MSVC v9
Hi Tanguy,
On Wed, Feb 4, 2009 at 12:22 PM, Tanguy Fautre
<tang...@aristechnologies.com> wrote:
> Robert, do you thing the problem may be serious enough to possibly motivate
> a code change for all operators of Vec3f and co as a workaround?
We could change code, it would all depend on how intrusive the changes
are, without code changes in front of me I can't make this judgement
call. Could you send me a modified Vec* files so I could do a review?
The other approach is to change the compile flags of the OSG to avoid
this bug. This wouldn't help 3rd party apps though.
Robert.
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