math: add a new math.easing module (#13226)

vlib/math/easing.v

@@ -0,0 +1,100 @@
+// Copyright (c) 2020-2022 Leah Lundqvist. All rights reserved.
+// Use of this source code is governed by a GPL license
+// that can be found in the LICENSE file.
+module math
+
+pub type EasingFunction = fn (arg_1 f64) f64
+
+pub enum EasingType {
+	linear
+	ease_in_quad
+	ease_out_quad
+	ease_in_out_quad
+	ease_in_cubic
+	ease_out_cubic
+	ease_in_out_cubic
+	ease_in_quart
+	ease_out_quart
+	ease_in_out_quart
+	ease_in_quint
+	ease_out_quint
+	ease_in_out_quint
+}
+
+fn linear(x f64) f64 {
+	return x
+}
+
+fn ease_in_quad(x f64) f64 {
+	return x * x
+}
+
+fn ease_out_quad(x f64) f64 {
+	return x * (2.0 - x)
+}
+
+fn ease_in_out_quad(x f64) f64 {
+	return if x < .5 { 2.0 * x * x } else { -1.0 + (4.0 - 2.0 * x) * x }
+}
+
+fn ease_in_cubic(x f64) f64 {
+	return x * x * x
+}
+
+fn ease_out_cubic(x f64) f64 {
+	return (x - 1.0) * (x - 1.0) * (x - 1.0) + 1
+}
+
+fn ease_in_out_cubic(x f64) f64 {
+	return if x < .5 { 4.0 * x * x * x } else { (x - 1.0) * (2.0 * x - 2.0) * (2.0 * x - 2.0) + 1.0 }
+}
+
+fn ease_in_quart(x f64) f64 {
+	return x * x * x * x
+}
+
+fn ease_out_quart(x f64) f64 {
+	return 1.0 - (x - 1.0) * (x - 1.0) * (x - 1.0) * (x - 1.0)
+}
+
+fn ease_in_out_quart(x f64) f64 {
+	return if x < 0.5 {
+		8.0 * x * x * x * x
+	} else {
+		1.0 - 8.0 * (x - 1.0) * (x - 1.0) * (x - 1.0) * (x - 1.0)
+	}
+}
+
+fn ease_in_quint(x f64) f64 {
+	return x * x * x * x * x
+}
+
+fn ease_out_quint(x f64) f64 {
+	return 1.0 + (x - 1.0) * (x - 1.0) * (x - 1.0) * (x - 1.0) * (x - 1.0)
+}
+
+fn ease_in_out_quint(x f64) f64 {
+	return if x < 0.5 {
+		16.0 * x * x * x * x * x
+	} else {
+		1.0 + 16.0 * (x - 1.0) * (x - 1.0) * (x - 1.0) * (x - 1.0) * (x - 1.0)
+	}
+}
+
+pub fn easing(easingtype EasingType) EasingFunction {
+	match easingtype {
+		.linear { return linear }
+		.ease_in_quad { return ease_in_quad }
+		.ease_out_quad { return ease_out_quad }
+		.ease_in_out_quad { return ease_in_out_quad }
+		.ease_in_cubic { return ease_in_cubic }
+		.ease_out_cubic { return ease_out_cubic }
+		.ease_in_out_cubic { return ease_in_out_cubic }
+		.ease_in_quart { return ease_in_quart }
+		.ease_out_quart { return ease_out_quart }
+		.ease_in_out_quart { return ease_in_out_quart }
+		.ease_in_quint { return ease_in_quint }
+		.ease_out_quint { return ease_out_quint }
+		.ease_in_out_quint { return ease_in_out_quint }
+	}
+}