Pareen is a small library for parameterized inbetweening. The intended application is in game programming, where you sometimes have two discrete game states between which you want to transition smoothly for visualization purposes.
Pareen gives you tools for composing animations that are parameterized by time (i.e. mappings from time to some animated value) without constantly having to pass around time variables; it hides the plumbing, so that you need to provide time only once: when evaluating the animation.
Animations are composed similarly to Rust's iterators, so no memory allocations are necessary.
// An animation returning a constant value let anim1 = pareen::constant(1.0f64); // Animations can be evaluated at any time let value = anim1.eval(0.5); // Animations can be played in sequence let anim2 = anim1.seq(0.7, pareen::prop(0.25) + 0.5); // Animations can be composed and transformed in various ways let anim3 = anim2 .lerp(pareen::circle().cos()) .scale_min_max(5.0, 10.0) .backwards(1.0) .squeeze(0.5..=1.0); let anim4 = pareen::cubic(&[1.0, 2.0, 3.0, 4.0]) - anim3; let value = anim4.eval(1.0); assert_approx_eq!(value, 0.0);
Build an animation that depends on matching some expression.
Proportionally increase value from zero to 2π.
Return the value of one of two animations depending on a condition.
A constant animation, always returning the same value.
Evaluate a cubic polynomial in time.
Count from 0 to
Integrate an easing-in function from the
Integrate an easing-in-out function from the
Integrate an easing-out function from the
Turn any function
Proportionally increase value from zero to π.
An animation that returns time as its value.
Linearly interpolate between two animations, starting at time zero and finishing at time one.
An animation that returns a value proportional to time.
Evaluate a quadratic polynomial in time.
Proportionally increase value from zero to π/2.