28 lines
769 B
C#
28 lines
769 B
C#
using SMath = System.Math;
|
|
|
|
namespace Cryville.Common.Math {
|
|
// Ported from https://github.com/arian/cubic-bezier/blob/master/index.js
|
|
public static class CubicBezier {
|
|
public static float Evaluate(float t, float x1, float y1, float x2, float y2, float epsilon) {
|
|
float x = t, t0 = 0, t1 = 1, t2 = x;
|
|
|
|
if (t2 < t0) return Curve(t0, y1, y2);
|
|
if (t2 > t1) return Curve(t1, y1, y2);
|
|
|
|
while (t0 < t1) {
|
|
float tx = Curve(t2, x1, x2);
|
|
if (SMath.Abs(tx - x) < epsilon) return Curve(t2, y1, y2);
|
|
if (x > tx) t0 = t2;
|
|
else t1 = t2;
|
|
t2 = (t1 - t0) * .5f + t0;
|
|
}
|
|
|
|
return Curve(t2, y1, y2);
|
|
}
|
|
static float Curve(float t, float p1, float p2) {
|
|
float v = 1 - t;
|
|
return 3 * v * v * t * p1 + 3 * v * t * t * p2 + t * t * t;
|
|
}
|
|
}
|
|
}
|