Provides a (loose) port of Tween.js for Chicken Scheme. Other Schemes may work, though perhaps with some minor alterations.
(factorial n)
Memoized implementation of the factorial method. Provides O(n) computation, albeit with an O(1) average case. Requires O(n) memory.
You may reset the memory by whiping out the cache: (set! factorial* (make-vector 1 1))
(rationalize count value #!optional (epsilon 0))
Sometimes its useful to truncate the number of decimal places a floating point number is exact to. Sometimes it's also useful to do so after applying an epsilon value to smudge for floating point computation errors. This function can perform both operations.
Note that it is not a function to force a number to a particular number of significant digits.
(tween easing-function direction start stop percent)
Given an easing-function and a direction, this produces a value between start and stop that is representative of the provided percent.
direction may be one of the following symbols:
* in
* out
* inout
percent must be a value between 0.0 and 1.0.
start and stop must be numbers.
easing-function be of the form direction -> percent -> percent.
(interpolate selector-function value-vector percent)
Given a selector-function this produces a value within the range of values defined in value-vector that is representative of the provided percent.
value-vector must be a vector of numbers.
percent must be a value between 0.0 and 1.0.
selector-function must be of the form value-vector -> percent -> number
The following easing functions are available:
The following interpolation functions are available:
```scheme (define test-percents '(0.0 0.1 0.2 0.3 0.4 0.5 0.66 0.75 0.95 1.0))
(define (test-ease ease start stop) (let ((in '()) (out '()) (inout '())) (map (lambda (p) (set! in (cons (rationalize 2 (tween ease 'in start stop p)) in)) (set! out (cons (rationalize 2 (tween ease 'out start stop p)) out)) (set! inout (cons (rationalize 2 (tween ease 'inout start stop p)) inout)) ) (reverse test-percents)) `((in . ,in) (out . ,out) (inout . ,inout))))
;; Tests tweens for values between 0 and 10 (map (lambda (e) (display (list e 0 10 (test-ease e 0 10))) (newline)) (list linear-ease quadratic-ease cubic-ease quartic-ease quintic-ease sinusoidal-ease exponential-ease circular-ease elastic-ease back-ease bounce-ease))
;; Tests interpolation for values in the given set (let ((v '(0 1 2 3 4 5 10 15 20 25 30 35 40 45 50))) (map (lambda (s) (display (list s v (test-select s (list->vector v))))) (list linear-select bezier-select catmullrom-select)))
;; Tween test produces:
(#
;; Interpolation test produces:
(#
Copyright 2012 Daniel J. Leslie. All rights reserved.
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