interpolate

SCView extensions

part of wslib

a number of interpolation functions.

there are a number of types of interpolation available, and a number of ways to do it.

interpolation types

cubic interpolation:

'spline' : basic spline interpolation with automatic control points; extra argument: amt for the control points.

amt = 0 will result in sine-like interpolation.

the default amt is ( 0.75 / (1.9**0.5) ), for 2D circle approximation

'hermite' : simplified spline interpolation with fixed amt = 1/3, as used by many UGens ( DelayC, PlayBuf etc)

'bspline' : better curves but higher cpu. bspline also has an amt argument, which defines the order.

the default amt is 4.

other interpolation:

'quad' : not correct yet

'sine' : wraps s-shaped sine curves between steps

'linear' : linear interpolation

'step' : step interpolation

There is also the possibility of entering your own control points for the cubic interpolation.

methods

Array:intAt( index, type, loop, extra )

returns an interpolated value from the array at index with type interpolation. if loop == true the curve after the last point will bend towards the first. extra contains the extra arguments for specific types.

[0,1,5,2].intAt( 2.5 );

[0,1,5,2].intAt( 2.5, \hermite );

[0,1,5,2].intAt( 2.5, \bspline );

Array:atL ( index, loop ), atH ( index, loop ), atS ( index, loop, extra ),

atB ( index, loop, extra ), atSin ( index, loop )

shortcuts for all intAt types

Array:resize ( newSize, type, loop, extra )

resizes the array to newSize with type interpolation.

[0,1,5,2].resize( 100, \hermite ).plot;

(

a = { 1.0.rand2 } ! 10;

({ |i| a.resize( 200, [\linear, \step, \hermite, \spline, \bspline][i] ) } ! 5)

.flop.flat.plot(numChannels: 5);

)

Array:interpolate ( division, type, loop, extra )

expands the array to division values per input value with type interpolation.

[0,1,5,2].interpolate( 10, \hermite ).size;

[0,1,5,2].interpolate( 10, \hermite ).plot;

Array:splineIntFunction ( i, x1, x2 )

the basic cubic interpolation function with user given control points. The input aray should be of size = 2.

If you use an array for i, the function will run optimized ( calculates controls only once ).

[0,1].splineIntFunction( (0,0.01..1), 0.125, 1.75 ).plot;

examples

(

// hands on interpolation

// move the points around..

w = SCWindow( "y-axis interpolation" ).front;

u = SCUserView( w, w.view.bounds ).resize_(5);

w.decorate;

w.view.background_( Color.white );

m = SCPopUpMenu( w, 160@20 ).items_([

"cubic with controls",

"bspline",

"spline",

"hermite",

"linear",

"sine",

"step" ])

.action_({ |pu|

if( (pu.value == 2) or: (pu.value == 1) )

{ c.visible = true }

{ c.visible = false };

w.refresh; });

c = SCSlider( w, 200@20 )

.value_( (0.75 / (1.9**0.5)) )

.action_({ w.refresh })

.visible_( false );

p = [ 12@200, 138@50, 262@50, 388@200 ];

j = nil;

r = 7;

u.drawFunc_({ |uvw|

Color.black.alpha_(0.5).set;

Pen.line( 0@200, 400@200 ).stroke;

p[[0,3]].do({ |point, i| Pen.addArc( point, r, 0, 2pi ).stroke; });

if( m.value == 0 )

{ Color.red.set;

Pen.line( p[0], p[1] ).stroke;

Pen.line( p[2], p[3] ).stroke;

};

p[[1,2]].do({ |point, i| Pen.addArc( point, r, 0, 2pi ).stroke; });

Color.blue.set;

Pen.moveTo( p[0] );

switch( m.value,

0, { p[[0,3]].collect( _.y )

.splineIntFunction( (0,1/50..1), p[1].y, p[2].y )

.do({ |item, i|

Pen.lineTo(

i.linlin( 0, 50, p[0].x, p[3].x, \none )@item )

});

1, { p.collect(_.y).interpolate(15, 'bspline', false, c.value.linlin( 0,1,2,8 ).asInt )