Adjust animations based on FPS and skipped frames

data/core/init.lua

@@ -414,6 +414,7 @@ function core.init()
   core.redraw = true
   core.visited_files = {}
   core.restart_request = false
+  core.frames_lost = 0
 
   core.root_view = RootView()
   core.command_view = CommandView()
@@ -869,7 +870,13 @@ function core.run()
     else
       idle_iterations = 0
       local elapsed = system.get_time() - core.frame_start
-      system.sleep(math.max(0, frame_duration - elapsed))
+      local remaining = frame_duration - elapsed
+      if remaining > 0 then
+        core.frames_lost = 0
+        system.sleep(remaining)
+      else
+        core.frames_lost = math.ceil(elapsed / frame_duration) - 1
+      end
     end
   end
 end

data/core/view.lua

@@ -24,8 +24,10 @@ function View:move_towards(t, k, dest, rate)
   if not config.transitions or math.abs(val - dest) < 0.5 then
     t[k] = dest
   else
-    t[k] = common.lerp(val, dest, rate or 0.5)
-  end
+    rate = common.clamp(rate or 0.5, 1e-8, 1 - 1e-8)
+    local alpha = math.log(1 - rate)
+    local dt = (60 / config.fps) * (1 + core.frames_lost)
+    t[k] = common.lerp(val, dest, 1 - math.exp(alpha * dt))  end
   if val ~= dest then
     core.redraw = true
   end