Animatable Value

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SoCoder -> Snippet Home -> Timing

Cower	Created : 21 November 2010 Edited : 21 November 2010 System : Mac Language : C# Animatable Value Simple class to animate between two values over a set amount of time using GLFW's timing API
This is a fairly simple bit of code to animate between two values over a set amount of time (in seconds as far as I'm concerned, since that's what GLFW is using, but the units are completely arbitrary). Simple as it is, it's fairly handy to have as far as I'm concerned (I use stuff like this a lot in my code). Basically, you call [NAnimation setTime:time] each frame to keep all animations in sync (that is, one animation won't end up 3 milliseconds ahead of another), and the other stuff is all fairly self-explanatory (comments explain them). NAnimation.h #import <Cocoa/Cocoa.h> @interface NAnimation : NSObject { @private BOOL m_running; double m_startTime; double m_duration; double m_elapsed; double m_durationOverOne; double m_initial; double m_target; } + (void) setTime:(double)seconds; // The duration of the animation in seconds @property (assign, nonatomic) double duration; // The time in seconds that has elapsed since the animation started (not including time paused) @property (readonly) double elapsed; // The percentage (0.0 to 1.0) that the animation is complete. @property (readonly) double progress; // Property for the initial value. Setting this resets the animation. @property (assign, nonatomic) double initialValue; // Property for the target value. Setting this resets the animation. @property (assign, nonatomic) double targetValue; // Property to get the current value @property (readonly) double currentValue; - (id) initWithDuration:(double)seconds initialValue:(double)init target:(double)target; // stops and resets the animation - (void) reset; // stops, resets the animation, and then starts it again - (void) restart; // starts the animation (if paused, will resume the animation from where it left off) - (void) start; // stops the animation (can be resumed by sending the 'start' message - (void) stop; @end --v NAnimation.m #import "NAnimation.h" static double g_time = 0.0; @implementation NAnimation + (void) setTime:(double)seconds { g_time = seconds; } @synthesize duration=m_duration; @dynamic elapsed; @dynamic progress; @synthesize targetValue=m_target; @synthesize initialValue=m_initial; @dynamic currentValue; - (id) initWithDuration:(double)seconds initialValue:(double)init target:(double)target { self = [super init]; if (self) { m_elapsed = 0.0; m_duration = seconds; m_durationOverOne = 1.0 / seconds; m_initial = init; m_target = target; m_running = NO; } return self; } - (double) currentValue { double progress = self.progress; if (progress == 0.0) return m_initial; else if (progress == 1.0) return m_target; else return m_initial + (m_target - m_initial) * progress; } - (double) progress { double elapsed = self.elapsed; if (!m_running && m_duration <= elapsed) { return 1.0; } double progress = m_durationOverOne * elapsed; if (1.0 < progress) { [self stop]; return 1.0; } if (progress < 0.0) return 0.0; return progress; } - (void)reset { m_running = NO; m_elapsed = 0.0; } - (void)restart { [self reset]; [self start]; } - (void) start { if (m_running) return; m_startTime = g_time - m_elapsed; m_running = YES; } - (void) stop { if (!m_running) return; m_running = NO; m_elapsed = g_time - m_startTime; } - (double)elapsed { if (m_running) { return (m_elapsed = g_time - m_startTime); } return m_elapsed; } - (void) setDuration:(double)seconds { m_duration = seconds; m_durationOverOne = 1.0 / seconds; [self reset]; } - (void) setInitialValue:(double)init { [self reset]; m_initial = init; } - (void) setTargetValue:(double)target { [self reset]; m_target = target; } @end --v

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