marks: add documentation, more markings

src/plot/line.typ

@@ -186,8 +186,35 @@
 /// - axes (axes): Name of the axes to use for plotting. Reversing the axes
 ///   means rotating the plot by 90 degrees.
 /// - mark (string): Mark symbol to place at each distinct value of the
-///   graph. Uses the `mark` style key of `style` for drawing.
-/// - mark-size (float): Mark size in cavas units
+///   graph. Uses the `mark` style key of `style` for drawing:
+///
+///   ```cexample-vertical
+///   let points(offset) = ((offset, 0), (offset, 1))
+///
+///   plot.plot(size: (12, 2), axis-style: none, {
+///     plot.add(points(0), mark: "*")  // same as "x"
+///     plot.add(points(1), mark: "square")
+///     plot.add(points(2), mark: "triangle")
+///     plot.add(points(3), mark: "o")
+///     plot.add(points(4), mark: "+")
+///     plot.add(points(5), mark: "-")
+///     plot.add(points(6), mark: "|")
+///     plot.add(points(7), mark: "<>")
+///     plot.add(points(8), mark: 5)  // specify an integer to use a regular polygon.
+///
+///     // Alternatively, specify custom function:
+///     plot.add(points(9), mark: (pt, size, style) => {
+///       let top = (to: pt, rel: (0, size))
+///       let bot = (to: pt, rel: (0, -size))
+///       let left = (to: pt, rel: (-size/2, 0))
+///       let right = (to: pt, rel: (size/2, 0))
+///       cetz.draw.line(top, left, bot, right, close: true, ..style)
+///     })
+///    })
+///   ```
+///
+///
+/// - mark-size (float): Mark size in canvas units
 /// - data (array,function): Array of 2D data points (numeric) or a function
 ///   of the form `x => y`, where `x` is a value in `domain`
 ///   and `y` must be numeric or a 2D vector (for parametric functions).

src/plot/mark.typ

@@ -31,6 +31,13 @@
     draw.line(ll(pt), rr(pt), ..style)
   } else if mark == "|" {
     draw.line(tt(pt), bb(pt), ..style)
+  } else if mark == "diamond" or mark == "<>" {
+    draw.line(ll(pt), tt(pt), rr(pt), bb(pt), close: true, ..style)
+  } else if type(mark) == int and mark > 2 {
+    let pts = range(mark).map(i => (to: pt, rel: (90deg + 360deg * i / mark, size/2)))
+    draw.line(..pts, close: true, ..style)
+  } else if type(mark) == function {
+    mark(pt, size, style)
   }
 }