st/scroll-view-fade: Fix vertical top fading

The fade for the vertical top edge was calculating the fade ratio for a
larger height (up to where the bottom fade starts) than it was
displaying.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1674>

diff --git a/src/st/st-scroll-view-fade.glsl b/src/st/st-scroll-view-fade.glsl
index 2eacfd9af541ff6a2f9350bfcfd0e531e069b12b..e3f1a259f36c020a8df15e252943a9232a24ac26 100644 (file)
--- a/src/st/st-scroll-view-fade.glsl
+++ b/src/st/st-scroll-view-fade.glsl
@@ -55,7 +55,7 @@ void main ()
 
         float vfade_scale = height / vfade_offset;
         if (fade_top) {
-            ratio *= (fade_area_topleft[1] - y) / (fade_area_topleft[1] - fade_bottom_start);
+            ratio *= (fade_area_topleft[1] - y) / (fade_area_topleft[1] - fade_top_start);
         }
 
         if (fade_bottom) {