224 lines
8.4 KiB
Plaintext
224 lines
8.4 KiB
Plaintext
define smooth [require './monotonic-interpolate'].createInterpolant
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define intersection [require './intersection'].intersection
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define Bezier [require 'bezier-js']
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define tp [require './transform'].transformPoint
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define utp [require './transform'].untransform
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define [range-array low high] : begin {
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local a ()
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for [local j low] [j < high] [inc j] : a.push j
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return a
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}
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define SAMPLES 4
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define TINY 0.0001
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define LITTLE 0.01
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define KAPPA 0.51
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define COKAPPA : 1 - KAPPA
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define BKAPPA : KAPPA + 0.1
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define COBKAPPA : COKAPPA - 0.1
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define [Stroke] : begin {
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this.points = ()
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set this.gizmo (
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.xx 1
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.yx 0
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.xy 0
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.yy 1
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.x 0
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.y 0
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)
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return this
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}
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define [Stroke.prototype.set-transform t] : begin {
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this.gizmo = t
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return this
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}
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define [Stroke.bindParameters para] : begin {
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KAPPA = para.kappa
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COKAPPA = 1 - KAPPA
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COBKAPPA = COKAPPA - 0.1
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BKAPPA = KAPPA + 0.1
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}
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define [Stroke.prototype.set-width d1 d2] : begin {
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local point this.points`[this.points.length - 1]
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point.d1 = d1
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point.d2 = d2
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return this
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}
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define [Stroke.prototype.pen-direction x y] : begin {
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if [x.x !== nothing || x.y !== nothing] : begin {
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set y x.y
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set x x.x
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}
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local point this.points`[this.points.length - 1]
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point.pdx = x
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point.pdy = y
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return this
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}
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define [Stroke.prototype.start-from x y] : begin {
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this.points = ([tp this.gizmo (.x x .y y .onCurve true)])
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return this
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}
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define [Stroke.prototype.line-to x y] : begin {
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this.points.push [tp this.gizmo (.x x .y y .onCurve true)]
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return this
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}
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define [Stroke.prototype.curve-to xc yc x y] : begin {
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this.points.push [tp this.gizmo (.x xc .y yc .onCurve false)] [tp this.gizmo (.x x .y y .onCurve true)]
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return this
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}
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define [Stroke.prototype.cubic-to x1 y1 x2 y2 x y] : begin {
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this.points.push [tp this.gizmo (.x x1 .y y1 .onCurve false .cubic true)] [tp this.gizmo (.x x2 .y y2 .onCurve false .cubic true)] [tp this.gizmo (.x x .y y .onCurve true)]
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return this
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}
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define [Stroke.prototype.arc-vh-to x y] : begin {
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local last :utp this.gizmo this.points`[this.points.length - 1]
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this.cubic-to last.x [last.y + BKAPPA * [y - last.y]] [x + BKAPPA * [last.x - x]] y x y
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return this
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}
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define [Stroke.prototype.arc-hv-to x y] : begin {
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local last :utp this.gizmo this.points`[this.points.length - 1]
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this.cubic-to [last.x + BKAPPA * [x - last.x]] last.y x [y + BKAPPA * [last.y - y]] x y
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return this
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}
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define [dforward p0 p1 p2 p3] (
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.x [p0.x + [[-11] / 6 * p0.x + 3 * p1.x - 3 / 2 * p2.x + p3.x / 3] / TINY * LITTLE]
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.y [p0.y + [[-11] / 6 * p0.y + 3 * p1.y - 3 / 2 * p2.y + p3.y / 3] / TINY * LITTLE]
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)
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define [dbackward p0 p1 p2 p3] (
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.x [p0.x + [11 / 6 * p0.x - 3 * p1.x + 3 / 2 * p2.x - p3.x / 3] / TINY * LITTLE]
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.y [p0.y + [11 / 6 * p0.y - 3 * p1.y + 3 / 2 * p2.y - p3.y / 3] / TINY * LITTLE]
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)
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define [nonlinear a b c] : [Math.abs [[c.y - a.y] * [b.x - a.x] - [c.x - a.x] * [b.y - a.y]]] > TINY
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define [computeOffsetPoint curve t j foffset fpdx fpdy] : begin {
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local onpoint : curve.compute [t - j]
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local normal : curve.normal [t - j]
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return (.x onpoint.x + [foffset t] * [normal.x + [fpdx t]] .y onpoint.y + [foffset t] * [normal.y + [fpdy t]])
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}
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define [Stroke.prototype.form-stroke d1 d2] : begin {
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local d1s ([set d1 [if [this.points.0.d1 >= 0] this.points.0.d1 d1]])
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local d2s ([set d2 [if [this.points.0.d2 >= 0] this.points.0.d2 d2]])
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local pdxs (0)
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local pdys (0)
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local subSegments ()
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local p0 this.points.0
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for [local j 1] [j < this.points.length] [inc j] : begin {
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local p1 this.points`j
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piecewise {
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p1.onCurve : begin {
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subSegments.push : local seg : new Bezier p0.x p0.y [[p0.x + p1.x] / 2] [[p0.y + p1.y] / 2] p1.x p1.y
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d1s.push : set d1 [if [p1.d1 >= 0] p1.d1 d1]
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d2s.push : set d2 [if [p1.d2 >= 0] p1.d2 d2]
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local normalpt : seg.normal 0
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pdxs.push : if [p1.pdx !== nothing] [p1.pdx - normalpt.x] 0
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pdys.push : if [p1.pdy !== nothing] [p1.pdy - normalpt.y] 0
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p0 = p1
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}
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p1.cubic : begin {
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local p2 this.points`[j + 1]
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local p3 this.points`[j + 2]
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subSegments.push : local seg : new Bezier p0.x p0.y p1.x p1.y p2.x p2.y p3.x p3.y
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d1s.push : set d1 [if [p3.d1 >= 0] p3.d1 d1]
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d2s.push : set d2 [if [p3.d2 >= 0] p3.d2 d2]
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local normalpt : seg.normal 0
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pdxs.push : if [p3.pdx !== nothing] [p3.pdx - normalpt.x] 0
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pdys.push : if [p3.pdy !== nothing] [p3.pdy - normalpt.y] 0
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p0 = p3
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j = j + 2
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}
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true : begin {
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local p2 this.points`[j + 1]
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subSegments.push : local seg : new Bezier p0.x p0.y p1.x p1.y p2.x p2.y
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d1s.push : set d1 [if [p2.d1 >= 0] p2.d1 d1]
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d2s.push : set d2 [if [p2.d2 >= 0] p2.d2 d2]
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local normalpt : seg.normal 0
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pdxs.push : if [p2.pdx !== nothing] [p2.pdx - normalpt.x] 0
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pdys.push : if [p2.pdy !== nothing] [p2.pdy - normalpt.y] 0
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p0 = p2
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j = j + 1
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}
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}
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}
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if [this.points.0.pdx !== nothing] : set pdxs.0 [this.points.0.pdx - [subSegments.0.normal 0].x]
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if [this.points.0.pdy !== nothing] : set pdys.0 [this.points.0.pdy - [subSegments.0.normal 0].y]
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local f1 : smooth [range-array 0 d1s.length] d1s
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local f2 : smooth [range-array 0 d2s.length] [d2s.map [[x] -> [-x]]]
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local fpdx : smooth [range-array 0 d1s.length] pdxs
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local fpdy : smooth [range-array 0 d2s.length] pdys
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local left ()
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local right ()
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for [local j 0] [j < subSegments.length] [inc j] : begin {
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local curve subSegments`j
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foreach sample [range 0 SAMPLES] : begin {
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local t : j + sample / SAMPLES
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local tn : j + [sample + 1] / SAMPLES
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local lthis : computeOffsetPoint curve t j f1 fpdx fpdy
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local rthis : computeOffsetPoint curve t j f2 fpdx fpdy
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local lnext : computeOffsetPoint curve tn j f1 fpdx fpdy
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local rnext : computeOffsetPoint curve tn j f2 fpdx fpdy
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local lnthis1 : computeOffsetPoint curve [t + TINY] j f1 fpdx fpdy
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local rnthis1 : computeOffsetPoint curve [t + TINY] j f2 fpdx fpdy
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local lnnext1 : computeOffsetPoint curve [tn - TINY] j f1 fpdx fpdy
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local rnnext1 : computeOffsetPoint curve [tn - TINY] j f2 fpdx fpdy
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local lnthis2 : computeOffsetPoint curve [t + 2 * TINY] j f1 fpdx fpdy
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local rnthis2 : computeOffsetPoint curve [t + 2 * TINY] j f2 fpdx fpdy
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local lnnext2 : computeOffsetPoint curve [tn - 2 * TINY] j f1 fpdx fpdy
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local rnnext2 : computeOffsetPoint curve [tn - 2 * TINY] j f2 fpdx fpdy
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local lnthis3 : computeOffsetPoint curve [t + 3 * TINY] j f1 fpdx fpdy
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local rnthis3 : computeOffsetPoint curve [t + 3 * TINY] j f2 fpdx fpdy
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local lnnext3 : computeOffsetPoint curve [tn - 3 * TINY] j f1 fpdx fpdy
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local rnnext3 : computeOffsetPoint curve [tn - 3 * TINY] j f2 fpdx fpdy
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local dlthis [dforward lthis lnthis1 lnthis2 lnthis3]
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local drthis [dforward rthis rnthis1 rnthis2 rnthis3]
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local dlnext [dbackward lnext lnnext1 lnnext2 lnnext3]
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local drnext [dbackward rnext rnnext2 rnnext2 rnnext3]
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local il : intersection lthis.x lthis.y dlthis.x dlthis.y lnext.x lnext.y dlnext.x dlnext.y
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local ir : intersection rthis.x rthis.y drthis.x drthis.y rnext.x rnext.y drnext.x drnext.y
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if [[il.x != null] && [il.y != null] && [nonlinear lthis il lnext]] [then {
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left.push (.x lthis.x .y lthis.y .onCurve true) (.x il.x .y il.y .onCurve false)
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}] [else {
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left.push (.x lthis.x .y lthis.y .onCurve true)
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}]
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if [[ir.x != null] && [ir.y != null] && [nonlinear rthis ir rnext]] [then {
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right.push (.x rthis.x .y rthis.y .onCurve true) (.x ir.x .y ir.y .onCurve false)
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}] [else {
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right.push (.x rthis.x .y rthis.y .onCurve true)
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}]
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}
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left.push [begin [local last [computeOffsetPoint curve [j + 1] j f1 fpdx fpdy]] (.x last.x .y last.y .onCurve true)]
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right.push [begin [local last [computeOffsetPoint curve [j + 1] j f2 fpdx fpdy]] (.x last.x .y last.y .onCurve true)]
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}
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local shape : left.concat [right.reverse] :.map [[p] -> (.x p.x .y p.y .onCurve p.onCurve)]
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# reduce linear oncurve points
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for [local j 0] [j < shape.length - 1] [inc j] : begin {
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local p0 shape`j
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set still true
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for [local k [j + 1]] [still && k < shape.length - 1] [inc k] : begin {
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local p1 shape`k
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local p2 shape`[k + 1]
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if [p0.onCurve && p1.onCurve && p2.onCurve && [not [nonlinear p0 p1 p2]]] [then {
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set p1.removable true
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}] [else {
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set still false
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}]
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}
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set j [k - 1]
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}
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return ([shape.filter [[x] -> [x && [not x.removable]]]])
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}
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exports.Stroke = Stroke |