diff -r bec11707ed3f source/core/shape/quadric.cpp --- a/source/core/shape/quadric.cpp Thu Apr 09 20:57:14 2015 +0200 +++ b/source/core/shape/quadric.cpp Sat Aug 01 19:46:33 2015 +0200 @@ -840,7 +840,7 @@ { if (D != 0.0) { - T1[X] = J / (2.0 * D); + T1[X] = -J / (2.0 * D); } else { @@ -856,7 +856,7 @@ { if (G != 0.0) { - T1[Y] = J / (2.0 * G); + T1[Y] = -J / (2.0 * G); } else { @@ -872,7 +872,7 @@ { if (I != 0.0) { - T1[Z] = J / (2.0 * I); + T1[Z] = -J / (2.0 * I); } else { @@ -885,7 +885,7 @@ D += A * T1[X]; G += E * T1[Y]; I += H * T1[Z]; - J -= T1[X]*(A*T1[X] + 2.0*D) + T1[Y]*(E*T1[Y] + 2.0*G) + T1[Z]*(H*T1[Z] + 2.0*I); + J -= T1[X]*(A*T1[X] - 2.0*D) + T1[Y]*(E*T1[Y] - 2.0*G) + T1[Z]*(H*T1[Z] - 2.0*I); } else {