[3.38] surface-actor: Fix unobscurred_fraction calculation
This calculation wrongly applied a x2 - x1
pattern.
Closes #1971 (closed)
Part-of: !2169 (merged)
(cherry picked from commit 6204769f)
For Debian 11 and friends.
This calculation wrongly applied a x2 - x1
pattern.
Closes #1971 (closed)
Part-of: !2169 (merged)
(cherry picked from commit 6204769f)
For Debian 11 and friends.