diff --git a/effects/slidingpopups/slidingpopups.cpp b/effects/slidingpopups/slidingpopups.cpp
--- a/effects/slidingpopups/slidingpopups.cpp
+++ b/effects/slidingpopups/slidingpopups.cpp
@@ -4,6 +4,8 @@
 
 Copyright (C) 2009 Marco Martin notmart@gmail.com
 Copyright (C) 2018 Vlad Zahorodnii <vladzzag@gmail.com>
+Copyright (C) 2019 Sefa Eyeoglu <contact@scrumplex.net>
+Copyright (C) 2019 Nate Graham <nate@kde.org>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -136,33 +138,37 @@
     switch (animData.location) {
     case Location::Left:
         if (slideLength < geo.width()) {
-            data.multiplyOpacity(t);
+            data.multiplyOpacity(interpolate(0.0, 1.0, t));
         }
+
         data.translate(-interpolate(qMin(geo.width(), slideLength), 0.0, t));
         splitPoint = geo.width() - (geo.x() + geo.width() - screenRect.x() - animData.offset);
         region = QRegion(geo.x() + splitPoint, geo.y(), geo.width() - splitPoint, geo.height());
         break;
     case Location::Top:
         if (slideLength < geo.height()) {
-            data.multiplyOpacity(t);
+            data.multiplyOpacity(interpolate(0.0, 1.0, t));
         }
+
         data.translate(0.0, -interpolate(qMin(geo.height(), slideLength), 0.0, t));
         splitPoint = geo.height() - (geo.y() + geo.height() - screenRect.y() - animData.offset);
         region = QRegion(geo.x(), geo.y() + splitPoint, geo.width(), geo.height() - splitPoint);
         break;
     case Location::Right:
         if (slideLength < geo.width()) {
-            data.multiplyOpacity(t);
+            data.multiplyOpacity(interpolate(0.0, 1.0, t));
         }
+
         data.translate(interpolate(qMin(geo.width(), slideLength), 0.0, t));
         splitPoint = screenRect.x() + screenRect.width() - geo.x() - animData.offset;
         region = QRegion(geo.x(), geo.y(), splitPoint, geo.height());
         break;
     case Location::Bottom:
     default:
         if (slideLength < geo.height()) {
-            data.multiplyOpacity(t);
+            data.multiplyOpacity(interpolate(0.0, 1.0, t));
         }
+
         data.translate(0.0, interpolate(qMin(geo.height(), slideLength), 0.0, t));
         splitPoint = screenRect.y() + screenRect.height() - geo.y() - animData.offset;
         region = QRegion(geo.x(), geo.y(), geo.width(), splitPoint);
@@ -464,7 +470,7 @@
     animation.kind = AnimationKind::In;
     animation.timeLine.setDirection(TimeLine::Forward);
     animation.timeLine.setDuration((*dataIt).slideInDuration);
-    animation.timeLine.setEasingCurve(QEasingCurve::InOutSine);
+    animation.timeLine.setEasingCurve(QEasingCurve::InQuad);
 
     // If the opposite animation (Out) was active and it had shorter duration,
     // at this point, the timeline can end up in the "done" state. Thus, we have
@@ -503,7 +509,7 @@
     animation.kind = AnimationKind::Out;
     animation.timeLine.setDirection(TimeLine::Backward);
     animation.timeLine.setDuration((*dataIt).slideOutDuration);
-    animation.timeLine.setEasingCurve(QEasingCurve::InOutSine);
+    animation.timeLine.setEasingCurve(QEasingCurve::OutQuad);
 
     // If the opposite animation (In) was active and it had shorter duration,
     // at this point, the timeline can end up in the "done" state. Thus, we have