From dd5452527eb556b4d1eee394177e67b97099a9cd Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 8 Aug 2022 09:35:10 -0600
Subject: [PATCH] [instancer.solver] More fixes

---
 Lib/fontTools/varLib/instancer/solver.py | 22 ++++++++++++++++------
 Tests/varLib/instancer/solver_test.py    | 22 ++++++++++++++++++++++
 2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/Lib/fontTools/varLib/instancer/solver.py b/Lib/fontTools/varLib/instancer/solver.py
index 8bd8c1008..5a956341a 100644
--- a/Lib/fontTools/varLib/instancer/solver.py
+++ b/Lib/fontTools/varLib/instancer/solver.py
@@ -58,14 +58,24 @@ def _solveWithGain(tent, axisLimit):
 
         crossing = peak + ((1 - gain) * (upper - peak) / (1 - outGain))
 
-        loc1 = (peak, peak, crossing)
-        scalar1 = 1
+        loc = (peak, peak, crossing)
+        scalar = 1
 
-        loc2 = (crossing, axisMax, axisMax)
-        scalar2 = supportScalar({'tag': axisMax}, {'tag': tent})
+        out.append((scalar - gain, loc))
 
-        out.append((scalar1 - gain, loc1))
-        if (peak < upper):
+        if upper >= axisMax:
+            loc = (crossing, axisMax, axisMax)
+            scalar = supportScalar({'tag': axisMax}, {'tag': tent})
+
+            out.append((scalar - gain, loc))
+        else:
+            loc1 = (crossing, upper, axisMax)
+            scalar1 = 0
+
+            loc2 = (upper, axisMax, axisMax)
+            scalar2 = supportScalar({'tag': axisMax}, {'tag': tent})
+
+            out.append((scalar1 - gain, loc1))
             out.append((scalar2 - gain, loc2))
 
     # case 3: outermost limit still fits within F2Dot14 bounds;
diff --git a/Tests/varLib/instancer/solver_test.py b/Tests/varLib/instancer/solver_test.py
index b3bb90eb2..6936b7231 100644
--- a/Tests/varLib/instancer/solver_test.py
+++ b/Tests/varLib/instancer/solver_test.py
@@ -135,6 +135,28 @@ class RebaseTentTest(object):
                     (-.4, (.8, 1, 1)),
                 ]
             ),
+
+            #
+            # Misc corner cases
+            #
+
+            pytest.param(
+                (.5, .5, .5), (.5, .5, .5),
+                [
+                    (1, (0, 0, 0)),
+                ]
+            ),
+
+            pytest.param(
+                (.3, .5, .7), (.1, .5, .9),
+                [
+                    (1, (-1, 0, 1)),
+                    (-1, (0, 0.4999999999999999, 1)),
+                    (-1, (0.4999999999999999, 1, 1)),
+                    (-1, (-1, -.5, 0)),
+                    (-1, (-1, -1, -.5)),
+                ]
+            ),
         ],
     )
     def test_rebaseTent(self, tent, axisRange, expected):