feat: add easing fns

src/sine.rs

@@ -0,0 +1,16 @@
+use ::std::f32::consts::PI;
+
+/// <https://easings.net/#easeInSine>
+pub fn sine_in(t: f32) -> f32 {
+	1.0 - (t * PI / 2.0).cos()
+}
+
+/// <https://easings.net/#easeOutSine>
+pub fn sine_out(t: f32) -> f32 {
+	(t * PI / 2.0).sin()
+}
+
+/// <https://easings.net/#easeInOutSine>
+pub fn sine_in_out(t: f32) -> f32 {
+	-((PI * t).cos() - 1.0) / 2.0
+}