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UI: Generalize easing functions a bit.

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Unknown W. Brackets 2017-03-19 17:09:42 -07:00
parent 9f3415f43f
commit d8600229f4
2 changed files with 33 additions and 6 deletions
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36
ext/native/math/curves.cpp
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@ -45,13 +45,22 @@ float ease(int t, int fadeLength)
return ease((float)t / (float)fadeLength);
}
float bezierEaseInOut(float val) {
static const float x1 = 0.42f, x2 = 0.58f;
static const float a = 1.0f - 3.0f * x2 + 3.0f * x1;
static const float b = 3.0f * x2 - 6.0f * x1;
static const float c = 3.0f * x1;
template <int hundredthsX1, int hundredthsX2, int hundredthsY1 = 0, int hundredthsY2 = 100>
inline float bezierEaseFunc(float val) {
constexpr float x1 = hundredthsX1 / 100.0f;
constexpr float x2 = hundredthsX2 / 100.0f;
constexpr float a = 1.0f - 3.0f * x2 + 3.0f * x1;
constexpr float b = 3.0f * x2 - 6.0f * x1;
constexpr float c = 3.0f * x1;
constexpr float y1 = hundredthsY1 / 100.0f;
constexpr float y2 = hundredthsY2 / 100.0f;
constexpr float ya = 1.0f - 3.0f * y2 + 3.0f * y1;
constexpr float yb = 3.0f * y2 - 6.0f * y1;
constexpr float yc = 3.0f * y1;
float guess = val;
// Newton-Raphson calculation, no need to be too precise.
for (int i = 0; i < 4; ++i) {
float slope = 3.0f * a * guess * guess + 2.0f * b * guess + c;
if (slope == 0.0f) {
@ -62,8 +71,23 @@ float bezierEaseInOut(float val) {
guess -= x / slope;
}
return ((ya * guess + yb) * guess + yc) * guess;
}
return (-2.0f * guess + 3.0f) * guess * guess;
float bezierEase(float val) {
return bezierEaseFunc<25, 25, 10, 100>(val);
}
float bezierEaseInOut(float val) {
return bezierEaseFunc<42, 58>(val);
}
float bezierEaseIn(float val) {
return bezierEaseFunc<42, 100>(val);
}
float bezierEaseOut(float val) {
return bezierEaseFunc<0, 58>(val);
}
float sawtooth(int t, int period) {

3
ext/native/math/curves.h
View File

@ -14,7 +14,10 @@ float linearOut(int t, int fadeInLength);
float ease(float val);
float ease(int t, int fadeLength);
float bezierEase(float val);
float bezierEaseInOut(float val);
float bezierEaseIn(float val);
float bezierEaseOut(float val);
// need a bouncy ease