Fill Between

Introduction

Move beyond arrows — instead of just pointing at things, fill the space between them. With \nskFillBetween, you can create fluid, ambient shapes that connect elements without overwhelming them. These filled areas become a kind of visual glue: they group, guide, and suggest.

This visual overlay can help group related parts, emphasize sequential flows, or annotate areas without introducing new geometry.

Usage

\nskFillBetween[
  from=<source>, to=<target>,
  fill=<color>, border-color=<border-color>,
  opacity=<opacity>,
  edge=<straight|curved>,
  orientation=<vertical|horizontal>,
  corner-offset=<dimension>
]

Parameter Overview

Parameter	Description	Default
`from`	ID of the first block or coordinate	required
`to`	ID of the second block or coordinate	required
`fill`	Fill color between elements	transparent
`border-color`	Border color of the filled area	none
`opacity`	Opacity of the filled area (`0`–`1`)	`1`
`edge`	Determines if edges are `straight` or `curved`	`straight`
`orientation`	Direction of filling: `vertical` or `horizontal`	`vertical`
`corner-offset`	Offset to adjust the corner alignment (straight edge)	`0mm`
`in`	Inbound angle	`{}`
`out`	Outbound angle	`{}`

Examples

Straight vs. Curved Edges

Here’s an illustrative example showcasing both straight and curved fills:

% Straight Edges
\nskContainer[text-north=Straight, text-north-loc=west,]{
  \nskBlock[id=ablock, text-center=\Large A, width=2cm, height=1cm, border-radius=0mm,]
  \nskBlock[id=bblock, text-center=B, last-pos={below=.8cm}, border-radius=0mm,]
  \nskFillBetween[
    from=ablock, to=bblock,
    edge=straight,orientation=vertical,corner-offset=0mm,
  ]
  \nskBlock[id=ablock, text-center=\Large A, width=1cm, height=2cm, border-radius=0mm, last-pos={above right=-.5cm and 1.5cm},]
  \nskBlock[id=bblock, text-center=B, last-pos={right=.8cm}, border-radius=0mm,]
  \nskFillBetween[
    from=ablock, to=bblock,
    edge=straight,orientation=horizontal,corner-offset=0mm,
  ]
}

Advanced Example

This advanced use case demonstrates multiple fills, annotations, and coordinate-based fills:

examples/r-fields.tex

% block 0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <<<
\nskBlock[id=ba, width=8cm, height=1cm, border-radius=1mm,]
\nskMarkPath[
  path-width=8cm,skip-first=true, skip-last=true,step=10mm
]{(ba.south west) -- (ba.south east)}{
  \draw[black] (0,0) -- (0,1cm);
}
 
\foreach \i in {0,...,8}
  {
    \nskCoord[id=rat\i, pos={left=0mm of ba.north west}, shift-x=(10mm*\i), shift-y=4mm, marker=none,]
    \nskCoord[id=ra\i, pos={left=0mm of ba.south west}, shift-x=(10mm*\i), shift-y=0mm, marker=none,]
  }
 
\nskBlock[
  id=rb00,fill=none,shadow=false,border-color=none, border-radius=0mm,
  width=3cm, height=1cm,pos={above right=-1.3mm and 0mm of ra0},
  anchor=south west,
]
\nskBlock[
  id=rb01,fill=none,shadow=false,border-color=none, border-radius=0mm,
  width=3cm, height=1cm,pos={above right=-1.3mm and 0mm of ra5},
  anchor=south west,
]
 
% block 1 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <<<
\nskBlock[id=bb, width=2cm, height=1cm, pos={below=3cm of ba}, border-radius=1mm,]
\nskMarkPath[
  path-width=2cm,skip-first=true, skip-last=true,step=10mm
]{(bb.south west) -- (bb.south east)}{
  \draw[black] (0,0) -- (0,1cm);
}
 
\nskBlock[
  id=rb10,fill=none,shadow=false,border-color=none,
  width=1cm, height=1cm,pos={above right=0cm of bb.south west},
  anchor=south west,
]
\nskBlock[
  id=rb11,fill=none, shadow=false,border-color=none,
  width=1cm, height=1cm,pos={above right=0cm and 1cm of bb.south west},
  anchor=south west,
]
 
% measures ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <<<
\nskConnect[id=t0, from=rat0, to=rat3, arrow-tip={|-}, arrow-style={very thick}, shorten-to=.5mm,]
\nskConnect[
  id=t1,from=rat3,to=rat5,color=nskStrongCyan,
  arrow-tip={|-|},arrow-style={very thick},shorten-to=.5mm,
]
\nskConnect[id=t2,from=rat5, to=rat8, arrow-tip={-|},arrow-style={very thick},]
 
% ttext ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <<<
\nskMarkPath[at=.5,]{t0}{\node[above] {$s_l\cdot r_l$};}
\nskMarkPath[at=.5,]{t1}{\node[above] {$r_l=2$};}
\nskMarkPath[at=.5,]{t2}{\node[above] {$s_{l-1}$};}
 
% fills ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <<<
\nskFillBetween[from=ba, to=bb, edge=curved, orientation=vertical]
\nskFillBetween[from=rb00, to=rb10, edge=curved, orientation=vertical]
\nskFillBetween[from=rb01, to=rb11, edge=curved, orientation=vertical]
 
% annotate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <<<
\nskAnnotate[
  pos={right=2cm of ba},
  anchor-from=west,
  connect-to=ba.east,
  header={\nskBlockIDLast[1]},
  fill=none,
  header={Explanation},
  border-type=none,
  title={Key Observations},
  text={
      This is an important portion.
    },
  text-align=justify,
  connect-opts = {
      arrow-style={dotted, thick},
    },
  tikz-opts={},
]
 
\nskAnnotate[
  pos={right=5cm of rb11},
  anchor-from=west,
  connect-to=rb11.east,
  header={\nskBlockIDLast[1]},
  fill=none,
  header={Explanation},
  border-type=none,
  title={Key Observations},
  text={
      This is an important portion.
    },
  text-align=justify,
  connect-opts = {
      arrow-style={dotted, thick},
    },
  tikz-opts={},
]

Best Practices

Less is more: avoid flooding the diagram.
Use low-opacity or brand-tinted fills to avoid visual conflict.
Combine fills with annotations for clarity — use them to imply, not just decorate.

Key Takeaway

The \nskFillBetween command provides an effective method to visually emphasize regions and relationships between diagram elements, enhancing both clarity and aesthetics with customizable fills, edges, and orientation controls.

Reference Table

Prop	Type	Default
corner-offset?	`dimension`	`{}`
draw?	`token list`	`nskStrongBlue!50`
edge?	`choice`	`straight`
fill?	`token list`	`nskStrongBlue!20`
from?	`token list`	`{}`
opacity?	`number`	`0.4`
orientation?	`choice`	`vertical`
to?	`token list`	`{}`
in?	`token list`	`{}`
out?	`token list`	`{}`

Fill Between

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