[WIP] Add RBBRubberbandAnimation

RBBAnimation.xcodeproj/project.pbxproj

@@ -7,6 +7,12 @@
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@@ -37,6 +45,8 @@
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+		549ECA8518F7010400D968C7 /* RBBDampedHarmonicOscillatonSpec.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RBBDampedHarmonicOscillatonSpec.m; sourceTree = "<group>"; };
+		549ECA8718F7028E00D968C7 /* RBBRubberbandAnimationSpec.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RBBRubberbandAnimationSpec.m; sourceTree = "<group>"; };
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@@ -326,6 +342,10 @@
 				545D5AB9180B1FAE00FC94AB /* RBBTweenAnimation.m */,
 				545D5AC3180C138D00FC94AB /* RBBSpringAnimation.h */,
 				545D5AC4180C138D00FC94AB /* RBBSpringAnimation.m */,
+				545FEFD418F177B000900B78 /* RBBRubberbandAnimation.h */,
+				545FEFD518F177B000900B78 /* RBBRubberbandAnimation.m */,
+				5466A9B318F6C2260090E3E6 /* RBBDampedHarmonicOscillaton.h */,
+				5466A9B418F6C2260090E3E6 /* RBBDampedHarmonicOscillaton.m */,
 				54D5EA87181AE8620014896C /* RBBLinearInterpolation.h */,
 				54D5EA88181AE8620014896C /* RBBLinearInterpolation.m */,
 				545D5AC0180B5E8400FC94AB /* RBBEasingFunction.h */,
@@ -358,8 +378,10 @@
 			isa = PBXGroup;
 			children = (
 				5466C56218082D4200652BDC /* RBBBlockBasedArraySpec.m */,
+				549ECA8518F7010400D968C7 /* RBBDampedHarmonicOscillatonSpec.m */,
 				540F65AA18F82B3E005A6BB8 /* RBBLinearInterpolationSpec.m */,
 				549ECA8318F6ECFC00D968C7 /* RBBSpringAnimationSpec.m */,
+				549ECA8718F7028E00D968C7 /* RBBRubberbandAnimationSpec.m */,
 				54F3AE441807394800E1E688 /* Supporting Files */,
 			);
 			path = Specs;
@@ -386,6 +408,8 @@
 				549ECAC418F8157200D968C7 /* RBBSpringAnimation.h in Headers */,
 				549ECACA18F8157200D968C7 /* RBBCubicBezier.h in Headers */,
 				549ECAC018F8157200D968C7 /* RBBCustomAnimation.h in Headers */,
+				540935651905223A007565F7 /* RBBDampedHarmonicOscillaton.h in Headers */,
+				540935661905223D007565F7 /* RBBRubberbandAnimation.h in Headers */,
 				549ECAC618F8157200D968C7 /* RBBLinearInterpolation.h in Headers */,
 				540F65A718F82347005A6BB8 /* NSValue+PlatformIndependence.h in Headers */,
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@@ -695,6 +719,8 @@
 				549ECAC718F8157200D968C7 /* RBBLinearInterpolation.m in Sources */,
 				549ECABF18F8157200D968C7 /* RBBAnimation.m in Sources */,
 				549ECACD18F8157200D968C7 /* RBBBlockBasedArray.m in Sources */,
+				5409356719052241007565F7 /* RBBRubberbandAnimation.m in Sources */,
+				5409356419052226007565F7 /* RBBDampedHarmonicOscillaton.m in Sources */,
 				549ECACB18F8157200D968C7 /* RBBCubicBezier.m in Sources */,
 				540F65A918F82347005A6BB8 /* NSValue+PlatformIndependence.m in Sources */,
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@@ -707,6 +733,8 @@
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 				549ECABE18F8155B00D968C7 /* RBBSpringAnimationSpec.m in Sources */,
 				540F65AC18F82C67005A6BB8 /* RBBLinearInterpolationSpec.m in Sources */,
+				5409356919052251007565F7 /* RBBRubberbandAnimationSpec.m in Sources */,
+				540935681905224C007565F7 /* RBBDampedHarmonicOscillatonSpec.m in Sources */,
 			);
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@@ -720,6 +748,8 @@
 				54D5EA89181AE8620014896C /* RBBLinearInterpolation.m in Sources */,
 				545D5AC2180B5E8400FC94AB /* RBBEasingFunction.m in Sources */,
 				5466C56118082BEB00652BDC /* RBBBlockBasedArray.m in Sources */,
+				545FEFD618F177B000900B78 /* RBBRubberbandAnimation.m in Sources */,
+				5466A9B518F6C2260090E3E6 /* RBBDampedHarmonicOscillaton.m in Sources */,
 				545D5ABA180B1FAE00FC94AB /* RBBTweenAnimation.m in Sources */,
 				545D5AC5180C138D00FC94AB /* RBBSpringAnimation.m in Sources */,
 				54F3AE351807394800E1E688 /* RBBAnimation.m in Sources */,
@@ -733,6 +763,8 @@
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 				5466C56318082D4200652BDC /* RBBBlockBasedArraySpec.m in Sources */,
 				549ECA8418F6ECFC00D968C7 /* RBBSpringAnimationSpec.m in Sources */,
+				549ECA8618F7010400D968C7 /* RBBDampedHarmonicOscillatonSpec.m in Sources */,
+				549ECA8818F7028E00D968C7 /* RBBRubberbandAnimationSpec.m in Sources */,
 				540F65AB18F82B3E005A6BB8 /* RBBLinearInterpolationSpec.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

RBBAnimation/NSValue+PlatformIndependence.h

@@ -6,6 +6,10 @@
 //  Copyright (c) 2014 Robert Böhnke. All rights reserved.
 //
 
+#if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
+#import <UIKit/UIKit.h>
+#endif
+
 #import <Foundation/Foundation.h>
 
 @interface NSValue (PlatformIndependence)

RBBAnimation/NSValue+PlatformIndependence.m

@@ -6,10 +6,6 @@
 //  Copyright (c) 2014 Robert Böhnke. All rights reserved.
 //
 
-#if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
-#import <UIKit/UIKit.h>
-#endif
-
 #import "NSValue+PlatformIndependence.h"
 
 @implementation NSValue (PlatformIndependence)

RBBAnimation/RBBDampedHarmonicOscillaton.h

@@ -0,0 +1,13 @@
+//
+//  RBBDampedHarmonicOscillaton.h
+//  RBBAnimation
+//
+//  Created by Robert Böhnke on 10/04/14.
+//  Copyright (c) 2014 Robert Böhnke. All rights reserved.
+//
+
+#import <QuartzCore/QuartzCore.h>
+
+typedef CGFloat (^RBBOsciallation)(CGFloat t);
+
+RBBOsciallation RBBDampedHarmonicOscillation(CGFloat x0, CGFloat damping, CGFloat mass, CGFloat stiffness, CGFloat velocity, BOOL allowsOverdamping);

RBBAnimation/RBBDampedHarmonicOscillaton.m

@@ -0,0 +1,45 @@
+//
+//  RBBDampedHarmonicOscillaton.m
+//  RBBAnimation
+//
+//  Created by Robert Böhnke on 10/04/14.
+//  Copyright (c) 2014 Robert Böhnke. All rights reserved.
+//
+
+#import "RBBDampedHarmonicOscillaton.h"
+
+RBBOsciallation RBBDampedHarmonicOscillation(CGFloat x0, CGFloat b, CGFloat m, CGFloat k, CGFloat v0, BOOL allowsOverdamping) {
+    NSCAssert(m > 0, @"mass must be greater than zero.");
+    NSCAssert(k > 0, @"stiffness must be greater than zero.");
+    NSCAssert(b > 0, @"damping must be greater than zero.");
+
+    CGFloat beta = b / (2 * m);
+    CGFloat omega0 = sqrtf(k / m);
+    CGFloat omega1 = sqrtf((omega0 * omega0) - (beta * beta));
+    CGFloat omega2 = sqrtf((beta * beta) - (omega0 * omega0));
+
+    if (!allowsOverdamping && beta > omega0) beta = omega0;
+
+    if (beta < omega0) {
+        // Underdamped
+        return ^(CGFloat t) {
+            CGFloat envelope = expf(-beta * t);
+
+            return envelope * (x0 * cosf(omega1 * t) + ((beta * x0 + v0) / omega1) * sinf(omega1 * t));
+        };
+    } else if (beta == omega0) {
+        // Critically damped
+        return ^(CGFloat t) {
+            CGFloat envelope = expf(-beta * t);
+
+            return envelope * (x0 + (beta * x0 + v0) * t);
+        };
+    } else {
+        // Overdamped
+        return ^(CGFloat t) {
+            CGFloat envelope = expf(-beta * t);
+
+            return envelope * (x0 * coshf(omega2 * t) + ((beta * x0 + v0) / omega2) * sinhf(omega2 * t));
+        };
+    }
+}

RBBAnimation/RBBRubberbandAnimation.h

@@ -0,0 +1,27 @@
+//
+//  RBBRubberbandAnimation.h
+//  RBBAnimation
+//
+//  Created by Robert Böhnke on 06/04/14.
+//  Copyright (c) 2014 Robert Böhnke. All rights reserved.
+//
+
+#import <QuartzCore/QuartzCore.h>
+
+#import "RBBAnimation.h"
+
+@interface RBBRubberbandAnimation : RBBAnimation
+
+@property (readwrite, nonatomic, assign) CGFloat damping;
+@property (readwrite, nonatomic, assign) CGFloat mass;
+@property (readwrite, nonatomic, assign) CGFloat stiffness;
+@property (readwrite, nonatomic, assign) CGPoint velocity;
+
+@property (readwrite, nonatomic, assign) CGPoint from;
+@property (readwrite, nonatomic, assign) CGPoint to;
+
+@property (readwrite, nonatomic, assign) BOOL allowsOverdamping;
+
+- (CFTimeInterval)durationForEpsilon:(double)epsilon;
+
+@end

RBBAnimation/RBBRubberbandAnimation.m

@@ -0,0 +1,95 @@
+//
+//  RBBRubberbandAnimation.m
+//  RBBAnimation
+//
+//  Created by Robert Böhnke on 06/04/14.
+//  Copyright (c) 2014 Robert Böhnke. All rights reserved.
+//
+
+#import "NSValue+PlatformIndependence.h"
+
+#import "RBBDampedHarmonicOscillaton.h"
+
+#import "RBBRubberbandAnimation.h"
+
+@implementation RBBRubberbandAnimation
+
+#pragma mark - Lifecycle
+
+- (id)init {
+    self = [super init];
+    if (self == nil) return nil;
+
+    self.damping = 10;
+    self.mass = 1;
+    self.stiffness = 100;
+
+    return self;
+}
+
+#pragma mark - KVO
+
++ (NSSet *)keyPathsForValuesAffectingAnimationBlock {
+    return [NSSet setWithArray:@[
+        @"damping",
+        @"mass",
+        @"stiffness",
+        @"velocity",
+        @"from",
+        @"to",
+        @"allowsOverdamping"
+    ]];
+}
+
+#pragma mark - RBBSpringAnimation
+
+- (CFTimeInterval)durationForEpsilon:(double)epsilon {
+    CGFloat beta = self.damping / (2 * self.mass);
+
+    CFTimeInterval duration = 0;
+    while (expf(-beta * duration) >= epsilon) {
+        duration += 0.1;
+    }
+
+    return duration;
+}
+
+#pragma mark - RBBAnimation
+
+- (RBBAnimationBlock)animationBlock {
+    CGFloat deltaX = self.from.x - self.to.x;
+    CGFloat deltaY = self.from.y - self.to.y;
+
+    RBBOsciallation oscillationX = RBBDampedHarmonicOscillation(deltaX, self.damping, self.mass, self.stiffness, self.velocity.x, self.allowsOverdamping);
+    RBBOsciallation oscillationY = RBBDampedHarmonicOscillation(deltaY, self.damping, self.mass, self.stiffness, self.velocity.y, self.allowsOverdamping);
+
+    CGFloat x0 = self.to.x;
+    CGFloat y0 = self.to.y;
+
+    return ^(CGFloat t, CGFloat _) {
+        CGPoint p = { .x = x0 + oscillationX(t), .y = y0 + oscillationY(t) };
+
+        return [NSValue rbb_valueWithCGPoint:p];
+    };
+}
+
+#pragma mark - NSObject
+
+- (id)copyWithZone:(NSZone *)zone {
+    RBBRubberbandAnimation *copy = [super copyWithZone:zone];
+    if (copy == nil) return nil;
+
+    copy->_damping = _damping;
+    copy->_mass = _mass;
+    copy->_stiffness = _stiffness;
+    copy->_velocity = _velocity;
+
+    copy->_from = _from;
+    copy->_to = _to;
+
+    copy->_allowsOverdamping = _allowsOverdamping;
+
+    return copy;
+}
+
+@end

RBBAnimation/RBBSpringAnimation.m

@@ -7,6 +7,7 @@
 //
 
 #import "RBBBlockBasedArray.h"
+#import "RBBDampedHarmonicOscillaton.h"
 #import "RBBLinearInterpolation.h"
 
 #import "RBBSpringAnimation.h"
@@ -58,51 +59,11 @@ - (CFTimeInterval)durationForEpsilon:(double)epsilon {
 #pragma mark - RBBAnimation
 
 - (RBBAnimationBlock)animationBlock {
-    CGFloat b = self.damping;
-    CGFloat m = self.mass;
-    CGFloat k = self.stiffness;
-    CGFloat v0 = self.velocity;
-
-    NSParameterAssert(m > 0);
-    NSParameterAssert(k > 0);
-    NSParameterAssert(b > 0);
-
-    CGFloat beta = b / (2 * m);
-    CGFloat omega0 = sqrtf(k / m);
-    CGFloat omega1 = sqrtf((omega0 * omega0) - (beta * beta));
-    CGFloat omega2 = sqrtf((beta * beta) - (omega0 * omega0));
-
-    CGFloat x0 = -1;
-
-    if (!self.allowsOverdamping && beta > omega0) beta = omega0;
-
-    CGFloat (^oscillation)(CGFloat);
-    if (beta < omega0) {
-        // Underdamped
-        oscillation = ^(CGFloat t) {
-            CGFloat envelope = expf(-beta * t);
-
-            return -x0 + envelope * (x0 * cosf(omega1 * t) + ((beta * x0 + v0) / omega1) * sinf(omega1 * t));
-        };
-    } else if (beta == omega0) {
-        // Critically damped
-        oscillation = ^(CGFloat t) {
-            CGFloat envelope = expf(-beta * t);
-
-            return -x0 + envelope * (x0 + (beta * x0 + v0) * t);
-        };
-    } else {
-        // Overdamped
-        oscillation = ^(CGFloat t) {
-            CGFloat envelope = expf(-beta * t);
-
-            return -x0 + envelope * (x0 * coshf(omega2 * t) + ((beta * x0 + v0) / omega2) * sinhf(omega2 * t));
-        };
-    }
+    CGFloat (^oscillation)(CGFloat) = RBBDampedHarmonicOscillation(-1, self.damping, self.mass, self.stiffness, self.velocity, self.allowsOverdamping);
 
     RBBLinearInterpolation lerp = RBBInterpolate(self.fromValue, self.toValue);
     return ^(CGFloat t, CGFloat _) {
-        return lerp(oscillation(t));
+        return lerp(1 + oscillation(t));
     };
 }