Added support for bounce easing functions

warrenm · Jun 9, 2011 · 2a6cb1a · 2a6cb1a
1 parent a651ada
commit 2a6cb1a
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Showing 4 changed files with 44 additions and 10 deletions.
diff --git a/AHEasing/PlaygroundViewController.m b/AHEasing/PlaygroundViewController.m
@@ -124,6 +124,10 @@ - (void)configureEasingFunction
 			break;
 		case CurveTypeBack:
 			currentFunction = (currentEasing == EaseIn) ? BackEaseIn : (currentEasing == EaseOut) ? BackEaseOut : BackEaseInOut;
+			break;
+		case CurveTypeBounce:
+			currentFunction = (currentEasing == EaseIn) ? BounceEaseIn : (currentEasing == EaseOut) ? BounceEaseOut : BounceEaseInOut;
+			break;
 	}
 
 	[graphView setEasingFunction:currentFunction];

diff --git a/AHEasing/easing.c b/AHEasing/easing.c
@@ -234,19 +234,22 @@ AHFloat ElasticEaseInOut(AHFloat p)
 	}
 }
 
-// Modeled after the overshooting cubic y = x^3 - x*sin(x*pi)
+// Modeled after the overshooting cubic y = x^3-x*sin(x*pi)
 AHFloat BackEaseIn(AHFloat p)
 {
 	return p * p * p - p * sin(p * M_PI);
 }
 
-// Modeled after overshooting cubic y = 1 - ((1-x)^3 - (1-x)*sin((1-x)*pi))
+// Modeled after overshooting cubic y = 1-((1-x)^3-(1-x)*sin((1-x)*pi))
 AHFloat BackEaseOut(AHFloat p)
 {
 	AHFloat f = (1 - p);
 	return 1 - (f * f * f - f * sin(f * M_PI));
 }
 
+// Modeled after the piecewise overshooting cubic function:
+// y = (1/2)*((2x)^3-(2x)*sin(2*x*pi))           ; [0, 0.5)
+// y = (1/2)*(1-((1-x)^3-(1-x)*sin((1-x)*pi))+1) ; [0.5, 1]
 AHFloat BackEaseInOut(AHFloat p)
 {
 	if(p < 0.5)
@@ -256,22 +259,44 @@ AHFloat BackEaseInOut(AHFloat p)
 	}
 	else
 	{
-		AHFloat f = (1 - (2 * p - 1));
+		AHFloat f = (1 - (2*p - 1));
 		return 0.5 * (1 - (f * f * f - f * sin(f * M_PI))) + 0.5;
 	}
 }
 
 AHFloat BounceEaseIn(AHFloat p)
 {
-	return p;
+	return 1 - BounceEaseOut(1 - p);
 }
 
 AHFloat BounceEaseOut(AHFloat p)
 {
-	return p;
+	if(p < 4/11.0)
+	{
+		return (121 * p * p)/16.0;
+	}
+	else if(p < 8/11.0)
+	{
+		return (363/40.0 * p * p) - (99/10.0 * p) + 17/5.0;
+	}
+	else if(p < 9/10.0)
+	{
+		return (4356/361.0 * p * p) - (35442/1805.0 * p) + 16061/1805.0;
+	}
+	else
+	{
+		return (54/5.0 * p * p) - (513/25.0 * p) + 268/25.0;
+	}
 }
 
 AHFloat BounceEaseInOut(AHFloat p)
 {
-	return p;
+	if(p < 0.5)
+	{
+		return 0.5 * BounceEaseIn(p*2);
+	}
+	else
+	{
+		return 0.5 * BounceEaseOut(p * 2 - 1) + 0.5;
+	}
 }
diff --git a/AHEasing/easing.h b/AHEasing/easing.h
@@ -70,8 +70,8 @@ AHFloat BackEaseOut(AHFloat p);
 AHFloat BackEaseInOut(AHFloat p);
 
 // Exponentially-decaying bounce easing
-//AHFloat BounceEaseIn(AHFloat p);
-//AHFloat BounceEaseOut(AHFloat p);
-//AHFloat BounceEaseInOut(AHFloat p);
+AHFloat BounceEaseIn(AHFloat p);
+AHFloat BounceEaseOut(AHFloat p);
+AHFloat BounceEaseInOut(AHFloat p);
 
 #endif
diff --git a/AHEasing/en.lproj/PlaygroundView.xib b/AHEasing/en.lproj/PlaygroundView.xib
@@ -88,7 +88,7 @@
 						<bool key="IBUIOpaque">NO</bool>
 						<string key="targetRuntimeIdentifier">IBCocoaTouchFramework</string>
 						<int key="IBSegmentControlStyle">2</int>
-						<int key="IBNumberOfSegments">10</int>
+						<int key="IBNumberOfSegments">11</int>
 						<int key="IBSelectedSegmentIndex">0</int>
 						<object class="NSArray" key="IBSegmentTitles">
 							<bool key="EncodedWithXMLCoder">YES</bool>
@@ -102,6 +102,7 @@
 							<string>Exp</string>
 							<string>Elastic</string>
 							<string>Back</string>
+							<string>Bounce</string>
 						</object>
 						<object class="NSMutableArray" key="IBSegmentWidths">
 							<bool key="EncodedWithXMLCoder">YES</bool>
@@ -115,6 +116,7 @@
 							<real value="0.0"/>
 							<real value="0.0"/>
 							<real value="0.0"/>
+							<real value="0.0"/>
 						</object>
 						<object class="NSMutableArray" key="IBSegmentEnabledStates">
 							<bool key="EncodedWithXMLCoder">YES</bool>
@@ -128,6 +130,7 @@
 							<boolean value="YES"/>
 							<boolean value="YES"/>
 							<boolean value="YES"/>
+							<boolean value="YES"/>
 						</object>
 						<object class="NSMutableArray" key="IBSegmentContentOffsets">
 							<bool key="EncodedWithXMLCoder">YES</bool>
@@ -141,6 +144,7 @@
 							<string>{0, 0}</string>
 							<string>{0, 0}</string>
 							<string>{0, 0}</string>
+							<string>{0, 0}</string>
 						</object>
 						<object class="NSMutableArray" key="IBSegmentImages">
 							<bool key="EncodedWithXMLCoder">YES</bool>
@@ -154,6 +158,7 @@
 							<reference ref="4"/>
 							<reference ref="4"/>
 							<reference ref="4"/>
+							<reference ref="4"/>
 						</object>
 					</object>
 					<object class="IBUISegmentedControl" id="942628741">