Fix a typo that prevented IsDroppingFrames() from working

sheepytina · sheepytina · commit ad2a902f901d · 2023-09-12T15:40:28.000+10:00
(Maybe more than a mere typo, but a typo was involved.)
diff --git a/soh/soh/Enhancements/resolution-editor/ResolutionEditor.cpp b/soh/soh/Enhancements/resolution-editor/ResolutionEditor.cpp
@@ -406,8 +406,9 @@ void AdvancedResolutionSettingsWindow::UpdateElement() {
 bool AdvancedResolutionSettingsWindow::IsDroppingFrames() {
     // a rather imprecise way of checking for frame drops.
     // but it's mostly there to inform the player of large drops.
-    const float threshold = CVarGetInteger("gInterpolationFPS", 20) / 20.0f - 4.1f;
-    return ImGui::GetIO().Framerate < threshold;
+    const short targetFPS = CVarGetInteger("gInterpolationFPS", 20);
+    const float threshold = targetFPS / 20.0f + 4.1f;
+    return ImGui::GetIO().Framerate < targetFPS - threshold;
 }
 
 bool AdvancedResolutionSettingsWindow::IsBoolArrayTrue(bool* foo) {
