[gegl] trasform-core.c: wrong inner product (the y axis goes down in images)

[Nicolas Robidoux <nrobidoux src gnome org>]

commit a4582dac5594fbfac7ba42449edfd547397f8603
Author: Nicolas Robidoux <nrobidoux git gnome org>
Date:   Mon Dec 3 22:06:29 2012 -0500

    trasform-core.c: wrong inner product (the y axis goes down in images)

 operations/transform/transform-core.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/operations/transform/transform-core.c b/operations/transform/transform-core.c
index acc60d4..bf9c138 100644
--- a/operations/transform/transform-core.c
+++ b/operations/transform/transform-core.c
@@ -754,7 +754,8 @@ transform_affine (GeglBuffer  *dest,
                 inverse.coeff[1][1] * (roi->y + (gdouble) 0.5) +
                 inverse.coeff[1][2];
 
-      if (inverse_jacobian.coeff[0][0] < inverse_jacobian.coeff[1][0])
+      if (inverse_jacobian.coeff[0][0] + inverse_jacobian.coeff[1][0] <
+	  (gdouble) 0.0)
         {
           /*
            * "Flip", that is, put the "horizontal start" at the end
@@ -774,7 +775,8 @@ transform_affine (GeglBuffer  *dest,
           flip_x = (gint) 1;
         }
 
-      if (inverse_jacobian.coeff[0][1] < inverse_jacobian.coeff[1][1])
+      if (inverse_jacobian.coeff[0][1] + inverse_jacobian.coeff[1][1] <
+	  (gdouble) 0.0)
         {
           /*
            * "Flip", that is, put the "vertical start" at the last