Hi all,
I'm having some issues with AutoTransform (scale to screen) and wide
aspect viewports. To reproduce do something like:
export OSG_WINDOW="0 0 800 600"
osgautotransform
Then zoom out until only "Autoscale with no min, max limits" is visible.
Then make the aspect of the window larger/wider. You will see that the
size of the text gets smaller.
I've followed that AutoTransform uses CullStack->pixelSize() (to
determine its scale) and that this uses
CullingSet::computePixelSizeVector().
I can't quite follow the code in computePixelSizeVector, but noticed
that the scaleRatio depends on both horizontal and vertical scales, but
AFAIK OSG automatically adjusts the projection matrix so that only
vertical scale matters. If I change:
float scaleRatio =
0.7071067811f/sqrtf(scale_00.length2()+scale_10.length2());
into
float scaleRatio = 0.5/sqrtf(scale_10.length2());
then the osgautotransform example behaves like I would expect, i.e. the
text stays the same size no matter what the window aspect. I'm not sure
this is a "solution" though.
So my questions:
- What does the output of computePixelSizeVector represent? Can I write
in a matrix multiplation form? MVP*vec?
- Will it work for ortho projections?
thanks
jp
BTW, the text getting smaller for wide aspect is also present in the
osgtext example for the pixel_size_on_screen line.
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