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// c = {
// finished: Whether or not we are finished
// }
/***
Base Class
==========
The base stepper class that will be
***/
SVG.Stepper = SVG.invent ({
create: function (fn) {
},
extend: {
step: function (current, target, dt, c) {
},
isComplete: function (dt, c) {
},
},
})
/***
Easing Functions
================
***/
SVG.Ease = SVG.invent ({
inherit: SVG.Stepper,
create: function (fn) {
SVG.Stepper.call(this, fn)
this.ease = SVG.easing[fn || SVG.defaults.timeline.ease] || fn
},
extend: {
step: function (from, to, pos) {
if(typeof from !== 'number') {
return pos < 1 ? from : to
}
return from + (to - from) * this.ease(pos)
},
isComplete: function (dt, c) {
return false
},
},
})
SVG.easing = {
'-': function (pos) { return pos },
'<>': function (pos) { return -Math.cos(pos * Math.PI) / 2 + 0.5 },
'>': function (pos) { return Math.sin(pos * Math.PI / 2) },
'<': function (pos) { return -Math.cos(pos * Math.PI / 2) + 1 },
bezier: function (t0, x0, t1, x1) {
return function (t) {
// TODO: FINISH
}
},
}
/***
Controller Types
================
***/
SVG.Controller = SVG.invent ({
inherit: SVG.Stepper,
create: function (fn) {
SVG.Stepper.call(this, fn)
this.stepper = fn
},
extend: {
step: function (current, target, dt, c) {
return this.stepper(current, target, dt, c)
},
isComplete: function (dt, c) {
return false
var result = false
for(var i = c.length; i--;) {
result = result || (Math.abs(c[i].error) < 0.01)
}
return result
},
},
})
SVG.Spring = function spring(duration, overshoot) {
// Apply the default parameters
duration = duration || 500
overshoot = overshoot || 15
// Calculate the PID natural response
var eps = 1e-10
var os = overshoot / 100 + eps
var zeta = -Math.log(os) / Math.sqrt(Math.PI ** 2 + Math.log(os) ** 2)
var wn = 4 / (zeta * duration / 1000)
// Calculate the Spring values
var D = 2 * zeta * wn
var K = wn * wn
// Return the acceleration required
return new SVG.Controller(
function (current, target, dt, c) {
if(dt == Infinity) return target
// Get the parameters
var error = target - current
var lastError = c.error || 0
var velocity = (error - c.error) / dt
// Apply the control to get the new position and store it
var control = -D * velocity - K * error
var newPosition = current + control
c.error = error
return newPosition
})
}
SVG.PID = function (P, I, D, antiwindup) {
P = P == null ? 0.1 : P
I = I == null ? 0.01 : I
D = D == null ? 0 : D
antiwindup = antiwindup == null ? 1000 : antiwindup
// Return the acceleration required
return new SVG.Controller(
function (current, target, dt, c) {
if(dt == Infinity) return target
var p = target - current
var i = (c.integral || 0) + p * dt
var d = (p - (c.error || 0)) / dt
// antiwindup
i = Math.max(-antiwindup, Math.min(i, antiwindup))
c.error = p
c.integral = i
return current + (P * p + I * i + D * d)
})
}
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