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curveElement

Element functions can be customized with set and show rules.

A curve consisting of movements, lines, and Bézier segments.

At any point in time, there is a conceptual pen or cursor.

• Move elements move the cursor without drawing.
• Line/Quadratic/Cubic elements draw a segment from the cursor to a new position, potentially with control point for a Bézier curve.
• Close elements draw a straight or smooth line back to the start of the curve or the latest preceding move segment.

For layout purposes, the bounding box of the curve is a tight rectangle containing all segments as well as the point (0pt, 0pt).

Positions may be specified absolutely (i.e. relatively to (0pt, 0pt)), or relative to the current pen/cursor position, that is, the position where the previous segment ended.

Bézier curve control points can be skipped by passing none or automatically mirrored from the preceding segment by passing auto.

Example

#curve(
  fill: blue.lighten(80%),
  stroke: blue,
  curve.move((0pt, 50pt)),
  curve.line((100pt, 50pt)),
  curve.cubic(none, (90pt, 0pt), (50pt, 0pt)),
  curve.close(),
)

Parameters

Parameters are the inputs to a function. They are specified in parentheses after the function name.

fill

none or color or gradient or tiling

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

How to fill the curve.

When setting a fill, the default stroke disappears. To create a curve with both fill and stroke, you have to configure both.

Default: none

fill-rule

str

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

The drawing rule used to fill the curve.

View example

// We use `.with` to get a new
// function that has the common
// arguments pre-applied.
#let star = curve.with(
  fill: red,
  curve.move((25pt, 0pt)),
  curve.line((10pt, 50pt)),
  curve.line((50pt, 20pt)),
  curve.line((0pt, 20pt)),
  curve.line((40pt, 50pt)),
  curve.close(),
)

#star(fill-rule: "non-zero")
#star(fill-rule: "even-odd")

Default: "non-zero"

stroke

none or auto or length or color or gradient or stroke or tiling or dictionary

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

How to stroke the curve.

Can be set to none to disable the stroke or to auto for a stroke of 1pt black if and only if no fill is given.

View example

#let down = curve.line((40pt, 40pt), relative: true)
#let up = curve.line((40pt, -40pt), relative: true)

#curve(
  stroke: 4pt + gradient.linear(red, blue),
  down, up, down, up, down,
)

Default: auto

components

content

Required Positional

Positional parameters are specified in order, without names.

Variadic

Variadic parameters can be specified multiple times.

The components of the curve, in the form of moves, line and Bézier segment, and closes.

Definitions

Functions and types can have associated definitions. These are accessed by specifying the function or type, followed by a period, and then the definition's name.

moveElement

Element functions can be customized with set and show rules.

Starts a new curve component.

If no curve.move element is passed, the curve will start at (0pt, 0pt).

View example

#curve(
  fill: blue.lighten(80%),
  fill-rule: "even-odd",
  stroke: blue,
  curve.line((50pt, 0pt)),
  curve.line((50pt, 50pt)),
  curve.line((0pt, 50pt)),
  curve.close(),
  curve.move((10pt, 10pt)),
  curve.line((40pt, 10pt)),
  curve.line((40pt, 40pt)),
  curve.line((10pt, 40pt)),
  curve.close(),
)

start

array

Required Positional

Positional parameters are specified in order, without names.

The starting point for the new component.

relative

bool

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

Whether the coordinates are relative to the previous point.

Default: false

lineElement

Element functions can be customized with set and show rules.

Adds a straight line from the current point to a following one.

View example

#curve(
  stroke: blue,
  curve.line((50pt, 0pt)),
  curve.line((50pt, 50pt)),
  curve.line((100pt, 50pt)),
  curve.line((100pt, 0pt)),
  curve.line((150pt, 0pt)),
)

end

array

Required Positional

Positional parameters are specified in order, without names.

The point at which the line shall end.

relative

bool

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

Whether the coordinates are relative to the previous point.

View example

#curve(
  stroke: blue,
  curve.line((50pt, 0pt), relative: true),
  curve.line((0pt, 50pt), relative: true),
  curve.line((50pt, 0pt), relative: true),
  curve.line((0pt, -50pt), relative: true),
  curve.line((50pt, 0pt), relative: true),
)

Default: false

quadElement

Element functions can be customized with set and show rules.

Adds a quadratic Bézier curve segment from the last point to end, using control as the control point.

View example

// Function to illustrate where the control point is.
#let mark((x, y)) = place(
  dx: x - 1pt, dy: y - 1pt,
  circle(fill: aqua, radius: 2pt),
)

#mark((20pt, 20pt))

#curve(
  stroke: blue,
  curve.move((0pt, 100pt)),
  curve.quad((20pt, 20pt), (100pt, 0pt)),
)

control

none or auto or array

Required Positional

Positional parameters are specified in order, without names.

The control point of the quadratic Bézier curve.

• If auto and this segment follows another quadratic Bézier curve, the previous control point will be mirrored.
• If none, the control point defaults to end, and the curve will be a straight line.

View example

#curve(
  stroke: 2pt,
  curve.quad((20pt, 40pt), (40pt, 40pt), relative: true),
  curve.quad(auto, (40pt, -40pt), relative: true),
)

end

array

Required Positional

Positional parameters are specified in order, without names.

The point at which the segment shall end.

relative

bool

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

Whether the control and end coordinates are relative to the previous point.

Default: false

cubicElement

Element functions can be customized with set and show rules.

Adds a cubic Bézier curve segment from the last point to end, using control-start and control-end as the control points.

View example

// Function to illustrate where the control points are.
#let handle(start, end) = place(
  line(stroke: red, start: start, end: end)
)

#handle((0pt, 80pt), (10pt, 20pt))
#handle((90pt, 60pt), (100pt, 0pt))

#curve(
  stroke: blue,
  curve.move((0pt, 80pt)),
  curve.cubic((10pt, 20pt), (90pt, 60pt), (100pt, 0pt)),
)

control-start

none or auto or array

Required Positional

Positional parameters are specified in order, without names.

The control point going out from the start of the curve segment.

• If auto and this element follows another curve.cubic element, the last control point will be mirrored. In SVG terms, this makes curve.cubic behave like the S operator instead of the C operator.

• If none, the curve has no first control point, or equivalently, the control point defaults to the curve's starting point.

View example

#curve(
  stroke: blue,
  curve.move((0pt, 50pt)),
  // - No start control point
  // - End control point at `(20pt, 0pt)`
  // - End point at `(50pt, 0pt)`
  curve.cubic(none, (20pt, 0pt), (50pt, 0pt)),
  // - No start control point
  // - No end control point
  // - End point at `(50pt, 0pt)`
  curve.cubic(none, none, (100pt, 50pt)),
)

#curve(
  stroke: blue,
  curve.move((0pt, 50pt)),
  curve.cubic(none, (20pt, 0pt), (50pt, 0pt)),
  // Passing `auto` instead of `none` means the start control point
  // mirrors the end control point of the previous curve. Mirror of
  // `(20pt, 0pt)` w.r.t `(50pt, 0pt)` is `(80pt, 0pt)`.
  curve.cubic(auto, none, (100pt, 50pt)),
)

#curve(
  stroke: blue,
  curve.move((0pt, 50pt)),
  curve.cubic(none, (20pt, 0pt), (50pt, 0pt)),
  // `(80pt, 0pt)` is the same as `auto` in this case.
  curve.cubic((80pt, 0pt), none, (100pt, 50pt)),
)

control-end

none or array

Required Positional

Positional parameters are specified in order, without names.

The control point going into the end point of the curve segment.

If set to none, the curve has no end control point, or equivalently, the control point defaults to the curve's end point.

end

array

Required Positional

Positional parameters are specified in order, without names.

The point at which the curve segment shall end.

relative

bool

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

Whether the control-start, control-end, and end coordinates are relative to the previous point.

Default: false

closeElement

Element functions can be customized with set and show rules.

Closes the curve by adding a segment from the last point to the start of the curve (or the last preceding curve.move point).

View example

// We define a function to show the same shape with
// both closing modes.
#let shape(mode: "smooth") = curve(
  fill: blue.lighten(80%),
  stroke: blue,
  curve.move((0pt, 50pt)),
  curve.line((100pt, 50pt)),
  curve.cubic(auto, (90pt, 0pt), (50pt, 0pt)),
  curve.close(mode: mode),
)

#shape(mode: "smooth")
#shape(mode: "straight")

mode

str

Settable

Settable parameters can be customized for all following uses of the function with a set rule.

How to close the curve.

Default: "smooth"

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