Added easing functions.

include/bx/easing.h

@@ -0,0 +1,265 @@
+/*
+ * Copyright 2011-2016 Branimir Karadzic. All rights reserved.
+ * License: https://github.com/bkaradzic/bx#license-bsd-2-clause
+ */
+
+#ifndef BX_EASING_H_HEADER_GUARD
+#define BX_EASING_H_HEADER_GUARD
+
+#include "fpumath.h"
+
+// Reference:
+// http://easings.net/
+// http://robertpenner.com/easing/
+
+namespace bx
+{
+	typedef float (*EaseFn)(float _t);
+
+	template<EaseFn ease>
+	float easeOut(float _t)
+	{
+		return 1.0f - ease(1.0f - _t);
+	}
+
+	template<EaseFn easeFrom0toH, EaseFn easeFromHto1>
+	float easeMix(float _t)
+	{
+		return _t < 0.5f
+			? easeFrom0toH(2.0f*_t)*0.5f
+			: easeFromHto1(2.0f*_t - 1.0f)*0.5f + 0.5f
+			;
+	}
+
+	inline float easeLinear(float _t)
+	{
+		return _t;
+	}
+
+	inline float easeInQuad(float _t)
+	{
+		return fsq(_t);
+	}
+
+	inline float easeOutQuad(float _t)
+	{
+		return easeOut<easeInQuad>(_t);
+	}
+
+	inline float easeInOutQuad(float _t)
+	{
+		return easeMix<easeInQuad, easeOutQuad>(_t);
+	}
+
+	inline float easeOutInQuad(float _t)
+	{
+		return easeMix<easeOutQuad, easeInQuad>(_t);
+	}
+
+	inline float easeInCubic(float _t)
+	{
+		return _t*_t*_t;
+	}
+
+	inline float easeOutCubic(float _t)
+	{
+		return easeOut<easeInCubic>(_t);
+	}
+
+	inline float easeInOutCubic(float _t)
+	{
+		return easeMix<easeInCubic, easeOutCubic>(_t);
+	}
+
+	inline float easeOutInCubic(float _t)
+	{
+		return easeMix<easeOutCubic, easeInCubic>(_t);
+	}
+
+	inline float easeInQuart(float _t)
+	{
+		return _t*_t*_t*_t;
+	}
+
+	inline float easeOutQuart(float _t)
+	{
+		return easeOut<easeInQuart>(_t);
+	}
+
+	inline float easeInOutQuart(float _t)
+	{
+		return easeMix<easeInQuart, easeOutQuart>(_t);
+	}
+
+	inline float easeOutInQuart(float _t)
+	{
+		return easeMix<easeOutQuart, easeInQuart>(_t);
+	}
+
+	inline float easeInQuint(float _t)
+	{
+		return _t*_t*_t*_t*_t;
+	}
+
+	inline float easeOutQuint(float _t)
+	{
+		return easeOut<easeInQuint>(_t);
+	}
+
+	inline float easeInOutQuint(float _t)
+	{
+		return easeMix<easeInQuint, easeOutQuint>(_t);
+	}
+
+	inline float easeOutInQuint(float _t)
+	{
+		return easeMix<easeOutQuint, easeInQuint>(_t);
+	}
+
+	inline float easeInSine(float _t)
+	{
+		return 1.0f - fcos(_t*piHalf);
+	}
+
+	inline float easeOutSine(float _t)
+	{
+		return easeOut<easeInSine>(_t);
+	}
+
+	inline float easeInOutSine(float _t)
+	{
+		return easeMix<easeInSine, easeOutSine>(_t);
+	}
+
+	inline float easeOutInSine(float _t)
+	{
+		return easeMix<easeOutSine, easeInSine>(_t);
+	}
+
+	inline float easeInExpo(float _t)
+	{
+		return fpow(2.0f, 10.0f * (_t - 1.0f) ) - 0.001f;
+	}
+
+	inline float easeOutExpo(float _t)
+	{
+		return easeOut<easeInExpo>(_t);
+	}
+
+	inline float easeInOutExpo(float _t)
+	{
+		return easeMix<easeInExpo, easeOutExpo>(_t);
+	}
+
+	inline float easeOutInExpo(float _t)
+	{
+		return easeMix<easeOutExpo, easeInExpo>(_t);
+	}
+
+	inline float easeInCirc(float _t)
+	{
+		return -(fsqrt(1.0f - _t*_t) - 1.0f);
+	}
+
+	inline float easeOutCirc(float _t)
+	{
+		return easeOut<easeInCirc>(_t);
+	}
+
+	inline float easeInOutCirc(float _t)
+	{
+		return easeMix<easeInCirc, easeOutCirc>(_t);
+	}
+
+	inline float easeOutInCirc(float _t)
+	{
+		return easeMix<easeOutCirc, easeInCirc>(_t);
+	}
+
+	inline float easeOutElastic(float _t)
+	{
+		return fpow(2.0f, -10.0f*_t)*fsin( (_t-0.3f/4.0f)*(2.0f*pi)/0.3f) + 1.0f;
+	}
+
+	inline float easeInElastic(float _t)
+	{
+		return easeOut<easeOutElastic>(_t);
+	}
+
+	inline float easeInOutElastic(float _t)
+	{
+		return easeMix<easeInElastic, easeOutElastic>(_t);
+	}
+
+	inline float easeOutInElastic(float _t)
+	{
+		return easeMix<easeOutElastic, easeInElastic>(_t);
+	}
+
+	inline float easeInBack(float _t)
+	{
+		return easeInCubic(_t) - _t*fsin(_t*pi);
+	}
+
+	inline float easeOutBack(float _t)
+	{
+		return easeOut<easeInBack>(_t);
+	}
+
+	inline float easeInOutBack(float _t)
+	{
+		return easeMix<easeInBack, easeOutBack>(_t);
+	}
+
+	inline float easeOutInBack(float _t)
+	{
+		return easeMix<easeOutBack, easeInBack>(_t);
+	}
+
+	inline float easeOutBounce(float _t)
+	{
+		if (4.0f/11.0f > _t)
+		{
+			return 121.0f/16.0f*_t*_t;
+		}
+
+		if (8.0f/11.0f > _t)
+		{
+			return 363.0f/40.0f*_t*_t
+				 -  99.0f/10.0f*_t
+				 +  17.0f/ 5.0f
+				 ;
+		}
+
+		if (9.0f/10.0f > _t)
+		{
+			return  4356.0f/ 361.0f*_t*_t
+				 - 35442.0f/1805.0f*_t
+				 + 16061.0f/1805.0f
+				 ;
+		}
+
+		return  54.0f/ 5.0f*_t*_t
+			 - 513.0f/25.0f*_t
+			 + 268.0f/25.0f
+			 ;
+	}
+
+	inline float easeInBounce(float _t)
+	{
+		return easeOut<easeOutBounce>(_t);
+	}
+
+	inline float easeInOutBounce(float _t)
+	{
+		return easeMix<easeInBounce, easeOutBounce>(_t);
+	}
+
+	inline float easeOutInBounce(float _t)
+	{
+		return easeMix<easeOutBounce, easeInBounce>(_t);
+	}
+
+} // namespace bx
+
+#endif // BX_EASING_H_HEADER_GUARD

include/bx/fpumath.h

@@ -102,16 +102,6 @@ namespace bx
 		return _a < 0.0f ? -1.0f : 1.0f;
 	}
 
-	inline float fstep(float _edge, float _a)
-	{
-		return _a < _edge ? 0.0f : 1.0f;
-	}
-
-	inline float fpulse(float _a, float _start, float _end)
-	{
-		return fstep(_a, _start) - fstep(_a, _end);
-	}
-
 	inline float fabsolute(float _a)
 	{
 		return fabsf(_a);
@@ -127,11 +117,21 @@ namespace bx
 		return sinf(_a);
 	}
 
+	inline float fasin(float _a)
+	{
+		return asinf(_a);
+	}
+
 	inline float fcos(float _a)
 	{
 		return cosf(_a);
 	}
 
+	inline float facos(float _a)
+	{
+		return acosf(_a);
+	}
+
 	inline float fpow(float _a, float _b)
 	{
 		return powf(_a, _b);
@@ -197,6 +197,21 @@ namespace bx
 		return result;
 	}
 
+	inline float fstep(float _edge, float _a)
+	{
+		return _a < _edge ? 0.0f : 1.0f;
+	}
+
+	inline float fpulse(float _a, float _start, float _end)
+	{
+		return fstep(_a, _start) - fstep(_a, _end);
+	}
+
+	inline float fsmoothstep(float _a)
+	{
+		return fsq(_a)*(3.0f - 2.0f*_a);
+	}
+
 	// References:
 	//  - Bias And Gain Are Your Friend
 	//    http://blog.demofox.org/2012/09/24/bias-and-gain-are-your-friend/