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GitHub Repository: hrydgard/ppsspp
 Path: blob/master/Common/Math/curves.cpp
Views: 1401
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#include <cmath>

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#include "Common/Math/math_util.h"

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#include "curves.h"

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float linearInOut(int t, int fadeInLength, int solidLength, int fadeOutLength) {

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	if (t < 0) return 0;

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	if (t < fadeInLength) {

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		return (float)t / fadeInLength;

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	}

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	t -= fadeInLength;

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	if (t < solidLength) {

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		return 1.0f;

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	}

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	t -= solidLength;

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	if (t < fadeOutLength) {

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		return 1.0f - (float)t / fadeOutLength;

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	}

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	return 0.0f;

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}

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float linearIn(int t, int fadeInLength) {

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	if (t < 0) return 0;

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	if (t < fadeInLength) {

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		return (float)t / fadeInLength;

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	}

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	return 1.0f;

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}

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float linearOut(int t, int fadeOutLength) {

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	return 1.0f - linearIn(t, fadeOutLength);

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}

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float ease(float val) {

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	if (val >= 1.0f) return 1.0f;

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	if (val <= 0.0f) return 0.0f;

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	return (float)(((-cosf(val * PI)) + 1.0f) * 0.5);

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}

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float ease(int t, int fadeLength)

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{

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	if (t <= 0.0f) return 0.0f;

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	if (t >= fadeLength) return 1.0f;

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	return ease((float)t / (float)fadeLength);

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}

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template <int hundredthsX1, int hundredthsX2, int hundredthsY1 = 0, int hundredthsY2 = 100>

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inline float bezierEaseFunc(float val) {

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	constexpr float x1 = hundredthsX1 / 100.0f;

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	constexpr float x2 = hundredthsX2 / 100.0f;

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	constexpr float a = 1.0f - 3.0f * x2 + 3.0f * x1;

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	constexpr float b = 3.0f * x2 - 6.0f * x1;

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	constexpr float c = 3.0f * x1;

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	constexpr float y1 = hundredthsY1 / 100.0f;

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	constexpr float y2 = hundredthsY2 / 100.0f;

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	constexpr float ya = 1.0f - 3.0f * y2 + 3.0f * y1;

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	constexpr float yb = 3.0f * y2 - 6.0f * y1;

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	constexpr float yc = 3.0f * y1;

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	float guess = val;

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	// Newton-Raphson calculation, no need to be too precise.

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	for (int i = 0; i < 4; ++i) {

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		float slope = 3.0f * a * guess * guess + 2.0f * b * guess + c;

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		if (slope == 0.0f) {

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			break;

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		}

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		float x = ((a * guess + b) * guess + c) * guess - val;

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		guess -= x / slope;

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	}

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	return ((ya * guess + yb) * guess + yc) * guess;

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}

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float bezierEase(float val) {

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	return bezierEaseFunc<25, 25, 10, 100>(val);

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}

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float bezierEaseInOut(float val) {

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	return bezierEaseFunc<42, 58>(val);

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}

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float bezierEaseIn(float val) {

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	return bezierEaseFunc<42, 100>(val);

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}

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float bezierEaseOut(float val) {

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	return bezierEaseFunc<0, 58>(val);

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}

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float sawtooth(int t, int period) {

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	return (t % period) * (1.0f / (period - 1));

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}

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float passWithPause(int t, int fadeInLength, int pauseLength, int fadeOutLength)

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{

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	if (t < fadeInLength) {

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		return -1.0f + (float)t / fadeInLength;

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	}

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	t -= fadeInLength;

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	if (t < pauseLength) {

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		return 0.0f;

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	}

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	t -= pauseLength;

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	if (t < fadeOutLength) {

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		return (float)t / fadeOutLength;

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	}

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	return 1.0f;

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}

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