ofPolyline smoothed seems broken in nightly

[ofZach]

was just working with a student and we noticed ofPolyline::getSmoothed() seems broken on nightly.

example code:

ofPolyline line;
for (int i = 0; i < 100; i++){
        float angle = ofMap(i, 0, 100, 0, PI);
        line.addVertex(400 + 200 * cos(angle),
                       400 + 200 * sin(angle));
    }
line = line.getSmoothed( (int)ofMap(mouseX, 0, ofGetWidth(), 0, 11));
line.draw();

in 0.10.1 it works as expected (half-circle shrinks slightly as you move the mouse), in nightly when you move the mouse over it does something strange.

investigating...

[ofTheo]

wow - I think this is another case of a bug with glm now not initializing variables by default.
hard to catch because of the templating.

https://github.com/openframeworks/openFrameworks/blame/master/libs/openFrameworks/graphics/ofPolyline.inl#L490

			T cur;

is not initialized so has garbage values.
Try changing it to:

			T cur(0);

See: #6397 (comment)

I am more and more tempted to do our next release with:
#define GLM_FORCE_CTOR_INIT 1

Or document really well the switch and how the #define can be used if needed.

[ofZach]

yeah I was just about to say, I tracked it down to T cur being different on the two releases :)

T cur(0) definitely fixes. I wonder if there are other subtle issues w/ initializing we should be looking for.