From b59c753a013f60192a6d4528fbd4b011d69b313f Mon Sep 17 00:00:00 2001 From: Alvin Penner Date: Mon, 18 May 2015 11:03:15 -0400 Subject: sbasis-to-bezier. avoid ill-conditioned behavior for anti-symmetric case. (Bug 1428267) Fixed bugs: - https://launchpad.net/bugs/1428267 (bzr r14161) --- src/2geom/sbasis-to-bezier.cpp | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'src') diff --git a/src/2geom/sbasis-to-bezier.cpp b/src/2geom/sbasis-to-bezier.cpp index a2e4253d2..98c400197 100644 --- a/src/2geom/sbasis-to-bezier.cpp +++ b/src/2geom/sbasis-to-bezier.cpp @@ -245,6 +245,8 @@ void sbasis_to_cubic_bezier (std::vector & bz, D2 const& sb) midx = 8*midx - 4*bz[0][X] - 4*bz[3][X]; // re-define relative to center midy = 8*midy - 4*bz[0][Y] - 4*bz[3][Y]; + if ((std::abs(midx) < EPSILON) && (std::abs(midy) < EPSILON)) + return; if ((std::abs(xprime[0]) < EPSILON) && (std::abs(yprime[0]) < EPSILON) && ((std::abs(xprime[1]) > EPSILON) || (std::abs(yprime[1]) > EPSILON))) { // degenerate handle at 0 : use distance of closest approach @@ -264,6 +266,10 @@ void sbasis_to_cubic_bezier (std::vector & bz, D2 const& sb) dely[1] = 0; } else if (std::abs(xprime[1]*yprime[0] - yprime[1]*xprime[0]) > // general case : fit mid fxn value 0.002 * std::abs(xprime[1]*xprime[0] + yprime[1]*yprime[0])) { // approx. 0.1 degree of angle + double test1 = (bz[1][Y] - bz[0][Y])*(bz[3][X] - bz[0][X]) - (bz[1][X] - bz[0][X])*(bz[3][Y] - bz[0][Y]); + double test2 = (bz[2][Y] - bz[0][Y])*(bz[3][X] - bz[0][X]) - (bz[2][X] - bz[0][X])*(bz[3][Y] - bz[0][Y]); + if (test1*test2 < 0) // reject anti-symmetric case, LP Bug 1428267 & Bug 1428683 + return; denom = xprime[1]*yprime[0] - yprime[1]*xprime[0]; for (int i = 0; i < 2; ++i) { numer = xprime[1 - i]*midy - yprime[1 - i]*midx; -- cgit v1.2.3