commit 8cf7076309da014e8e2af033b1c636785ae407cd
author Behdad Esfahbod <behdad@behdad.org> Wed Jan 25 14:35:35 2023 -0700
committer Behdad Esfahbod <behdad@behdad.org> Wed Jan 25 14:35:35 2023 -0700
tree 5d7972b9bdb73a2447f66c9d2b87b5449bfe7777
parent 626f8e4de3060376d12c77ac4967fd6fb908169a

[VarComposite] Fix skew

src/OT/glyf/VarCompositeGlyph.hh

diff --git a/src/OT/glyf/VarCompositeGlyph.hh b/src/OT/glyf/VarCompositeGlyph.hh
index 3685da7..dd34e36 100644
--- a/src/OT/glyf/VarCompositeGlyph.hh
+++ b/src/OT/glyf/VarCompositeGlyph.hh
@@ -156,9 +156,10 @@
 		    float skewX, float skewY)
   {
     // https://github.com/fonttools/fonttools/blob/f66ee05f71c8b57b5f519ee975e95edcd1466e14/Lib/fontTools/misc/transform.py#L255
+    // We need a sign difference compared to fonttools
     skewX = skewX * float (M_PI);
     skewY = skewY * float (M_PI);
-    float other[6] = {1.f, tanf (skewY), tanf (skewX), 1.f, 0.f, 0.f};
+    float other[6] = {1.f, tanf (skewY), -tanf (skewX), 1.f, 0.f, 0.f};
     transform (matrix, trans, other);
   }