backIn backInOut backOut bounceIn bounceInOut bounceOut byName circularIn circularInOut circularOut cubicIn cubicInOut cubicOut def elasticIn elasticInOut elasticOut exponentialIn exponentialInOut exponentialOut linear quadraticIn quadraticInOut quadraticOut quarticIn quarticInOut quarticOut quinticIn quinticInOut quinticOut sinusoidalIn sinusoidalInOut sinusoidalOut stepped

quadraticIn detail::quadraticInEasing quadraticIn {} inlineconstexpr Quadratic polynomial easing (t²) with gentle acceleration. The quadraticIn easing function uses a squared power curve for acceleration, providing the gentlest polynomial easing. It's more subtle than cubic but still provides noticeable easing. Characteristics: Gentle, smooth acceleration Polynomial with power of 2 Subtle but perceptible easing Good for beginners and subtle animations This easing is ideal for: Subtle UI motion: When easing should be felt but not seen Quick animations: Short durations where gentle curves work best Minimal designs: Interfaces prioritizing restraint Learning easings: Easy to understand and predict Mathematically: f(t) = t² // Gentle fade in auto opacity = tweeny::from(0.0f) .to(1.0f) .via(easing::quadraticIn) .during(20U) .build(); See also quadraticOut For gentle deceleration quadraticInOut For gentle motion at both ends cubicIn For more pronounced acceleration Visualize at https://easings.net/#easeInQuad