Comment 6 for bug 1421865

Revision history for this message
Liam P. White (liampwhite) wrote :

This revision changed experimental to use Cairo to render elliptical arcs:
https://bazaar.launchpad.net/~inkscape.dev/inkscape/experimental/revision/13462
Experimental was later merged back into trunk, and this at least explains why trunk renders this file correctly.

However, 0.91 still uses pathv_to_linear_and_cubic_beziers to render curves.
pathv_to_linear_and_cubic_beziers (src/helper/geom.cpp) attempts to estimate this elliptical arc using cubic Bézier curves, and gets it very, horribly wrong for this specific case. I've determined the problem to stem from within 2geom, and I unfortunately don't know enough of the math going on to really be able to tell where it is going wrong at this point.

I do know that the tailError (3 truncated terms) for the SBasis representing this SVGEllipticalArc is not an accurate to the real error that this conversion would incur.
https://bazaar.launchpad.net/~lib2geom-hackers/lib2geom/trunk/view/head:/src/2geom/sbasis.cpp#L45