polygon

Draws a closed polygon from explicit local-coordinate points. Useful for non-rectangular glyphs (trapezoids, arrows, custom shapes) that can't be expressed by the standard shape primitives.

gf.chart([{}])
  .mark(
    gf.polygon({
      points: [
        [0, 0],
        [60, 0],
        [50, 40],
        [10, 40],
      ],
      fill: "steelblue",
    })
  )
  .render(root, { w: 100, h: 60 });

Signature

polygon({ points, fill?, stroke?, strokeWidth?, opacity = 1 })

Parameters

Option	Type	Default	Description
points	[number, number][]	—	Vertices in local coordinates. GoFish is y-up: [0, 0] is the bottom-left
fill	string	"black"	Fill color
stroke	string	fill	Stroke color (defaults to fill)
strokeWidth	number	0	Stroke width
opacity	number	1	Opacity, 0–1 (applies to fill and stroke)

Coordinates

Points are interpreted in the local coordinate system of whatever places the polygon — typically a Layer or a constraint. The polygon's bounding box is the axis-aligned extent of its points; the parent placement system translates the whole polygon to position it.

GoFish is y-up internally, so a trapezoid whose wide edge sits at the bottom and narrow edge at the top is written:

polygon({
  points: [
    [0, 0], // bottom-left (the wider edge)
    [width, 0], // bottom-right
    [width - 10, h], // top-right  (inset)
    [10, h], // top-left   (inset)
  ],
});

Examples

// Trapezoidal weight glyph (from the pulley diagram)
polygon({
  points: [
    [0, 0],
    [width, 0],
    [width - 10, height],
    [10, height],
  ],
  fill: "#545454",
}).name("body");

// Triangle with stroke
polygon({
  points: [
    [0, 0],
    [40, 0],
    [20, 30],
  ],
  fill: "transparent",
  stroke: "black",
  strokeWidth: 2,
});

Notes

• The polygon is always closed — the last point connects back to the first automatically.
• Points are literals, not channel-bound. If you need a polygon whose shape depends on data, compose multiple polygons or use a derived mark (createMark).