Fix bounds for empty text nodes

[calumr]

_lineCount can be 0 if the TextBase has no text, so we get underflow if the alignment is one of the *_BOTTOM_BASE_LINE. Empty text nodes seem to come up in some of the .dxf files our users are importing.

I've worked around the bug in our code for now by deleting the empty text nodes on load.

[robertosfield]

Could provide details of how to reproduce the problem?

I think it would be better to have a dedicated code at the start of the method, along the lines of:

 if (empty) { set fallback values; return; }

[calumr]

    osg::ref_ptr<osg::Node> root = osgDB::readRefNodeFile("c:\\dev\\emptyTextNodes.dxf");

    osg::ComputeBoundsVisitor cbv;
    root->accept(cbv);
    if (cbv.getBoundingBox().xMax() > 10000)
    {
        osg::notify(osg::NOTICE) << "too big: "<< cbv.getBoundingBox().xMax() << std::endl;
    }

Run that on the attached .dxf, it should print "too big: 7.50612e+09".

emptyTextNodes.zip

[calumr]

I've updated the change to check if (_text.empty()) as you suggested.

[openscenegraph]

Hi Calum, Thanks for the model. I can't look at it right away, but once I've finished my current task I'll have a look. W.r.t to the changed commit. I don't know whether the Vec3{} usage will work with older compilers, () would be safer. Also using an if () else () block results in less readable code, for this type of usage I typically doing a return in the if (null_condition) { hande_nul_condition; return; } as it minimizes the changes required to unrelated code. Robert.

…

On Tue, 13 Apr 2021 at 14:20, Calum Robinson ***@***.***> wrote: I've updated the change to check if (_text.empty()) as you suggested. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1062 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABUA25TPPE4UO24MTSCN2LTIRAIRANCNFSM423H3SYA> .

[calumr]

All done. I had to move the _normal calculation up above the if, I hope this is OK. There's no rush on this, thanks for taking a look.

[robertosfield]

Looks good!

[robertosfield]

Also merged with 3.6 and MeshShaders branches.