BCSTM-Player |

external/tween-engine/src/equations/Elastic.cpp

@@ -0,0 +1,80 @@
+//
+//  Elastic.cpp
+//
+//  This code is derived from Universal Tween Engine
+//  Licensed under Apache License 2.0 - http://www.apache.org/licenses/LICENSE-2.0
+//
+
+#include <math.h>
+#include <TweenEngine/equations/Elastic.h>
+
+#define M_PI        3.14159265358979323846
+#define M_TWOPI         (M_PI * 2.0)
+
+namespace TweenEngine
+{
+    float ElasticIn::compute(float t) {
+        float a = amplitude;
+        float p = period;
+        if (t == 0) return 0;
+        if (t == 1) return 1;
+        if (!isPeriodSet) p = 0.3;
+        float s;
+        if (!isAmplitudeSet || a < 1) {
+            a = 1;
+            s = p/4.0;
+        } else {
+            s = p/(M_TWOPI) * (float)asin(1/a);
+        }
+        t -= 1;
+        return -(a*(float)pow(2,10*t) * (float)sin((t-s)*(M_TWOPI)/p ));
+    }
+    const char *ElasticIn::toString() { return "Elastic.IN"; }
+    void ElasticIn::setAmplitude(float a) { this->amplitude = a; this->isAmplitudeSet = true; }
+    void ElasticIn::setPeriod(float p) { this->period = p; this->isPeriodSet = true; }
+    
+    float ElasticOut::compute(float t) {
+        float a = amplitude;
+        float p = period;
+        if (t==0) return 0;
+        if (t==1) return 1;
+        if (!isPeriodSet) p = 0.3f;
+        float s;
+        if (!isAmplitudeSet || a < 1) {
+            a = 1;
+            s = p/4.0;
+        } else {
+            s = p/(M_TWOPI) * (float)asin(1/a);
+        }
+        return a*(float)pow(2,-10*t) * (float)sin((t-s)*(M_TWOPI)/p ) + 1;
+    }
+    const char *ElasticOut::toString() { return "Elastic.OUT"; }
+    void ElasticOut::setAmplitude(float a) { this->amplitude = a; this->isAmplitudeSet = true; }
+    void ElasticOut::setPeriod(float p) { this->period = p; this->isPeriodSet = true; }
+    
+    float ElasticInOut::compute(float t) {
+        float a = amplitude;
+        float p = period;
+        if (t==0) return 0;
+        t *= 2;
+        if (t==2) return 1;
+        if (!isPeriodSet) p = 0.3f*1.5f;
+        float s;
+        if (!isAmplitudeSet || a < 1) {
+            a = 1;
+            s = p/4.0;
+        } else {
+            s = p/(M_TWOPI) * (float)asin(1/a);
+        }
+        if (t < 1) {
+            t -= 1;
+            return -0.5f*(a*(float)pow(2,10*t) * (float)sin((t-s)*(M_TWOPI)/p));
+        } else {
+            t -= 1;
+            return a*(float)pow(2,-10*t) * (float)sin((t-s)*(M_TWOPI)/p)*0.5f + 1;
+        }
+    }
+    const char *ElasticInOut::toString() { return "Elastic.INOUT"; }
+    void ElasticInOut::setAmplitude(float a) { this->amplitude = a; this->isAmplitudeSet = true; }
+    void ElasticInOut::setPeriod(float p) { this->period = p; this->isPeriodSet = true; }
+}