Add easing functions normalized to [0, 1] range

lib/utils/easing.lua

@@ -0,0 +1,52 @@
+---- Функции смягчения, нормализованные к [0, 1]
+
+---@alias ease fun(x: number): number
+
+local easing = {}
+
+--- @type ease
+function easing.easeInSine(x)
+    return 1 - math.cos((x * math.pi) / 2);
+end
+
+--- @type ease
+function easing.easeOutSine(x)
+    return math.sin((x * math.pi) / 2);
+end
+
+--- @type ease
+function easing.easeInOutSine(x)
+    return -(math.cos(x * math.pi) - 1) / 2;
+end
+
+--- @type ease
+function easing.easeInQuad(x)
+    return x * x
+end
+
+--- @type ease
+function easing.easeOutQuad(x)
+    return 1 - (1 - x) * (1 - x)
+end
+
+--- @type ease
+function easing.easeInOutQuad(x)
+    return x < 0.5 and 2 * x * x or 1 - math.pow(-2 * x + 2, 2) / 2;
+end
+
+--- @type ease
+function easing.easeInCubic(x)
+    return x * x * x
+end
+
+--- @type ease
+function easing.easeOutCubic(x)
+    return 1 - math.pow(1 - x, 3)
+end
+
+--- @type ease
+function easing.easeInOutCubic(x)
+    return x < 0.5 and 4 * x * x * x or 1 - math.pow(-2 * x + 2, 3) / 2;
+end
+
+return easing