btDbvt.h array initialization issue

[Tassilo]

Hi,

I just stumbled upon the following line in btDbvt.h (2.73) which seem wrong to me:

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	btScalar			s1[2]={dot(xform.getOrigin(),d0),s1[0]};

s1 is used before a value is set...
Just wanted to report this.

Cheers

[Erwin Coumans]

Apparently the order of evaluation requires s1[1] to be initialized before s1[0], so the current implementation is correct.

The btDbvt::Intersect function has been taken out in Bullet 2.74, because it was unused. If it still existed, the implementation would have been more clear like this:

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btScalar tmp=dot(xform.getOrigin(),d0);
btScalar         s1[2]={tmp, tmp};

Thanks,
Erwin

[Tassilo]

Hi,

since it is possible to just use uninitialized variables in C/C++ (if it makes sense is another question), IMHO s[1] doesn't "require" s[0] to be initialized. The language standard does not specify the order of evaluation of expressions other than for ||, &&, comma and the ?: operators (which are explicitly specified in C++ 5.14, 5.15 and C99 6.5.13 and 6.5.14).
But well, it might be that I overlooked something, of course.

Well, in any case, your second snippet is guaranteed to be correct.

Cheers