Add primitive polar plot support

Author: johannes-wolf

src/plot/util.typ

@@ -20,6 +20,10 @@
     } else {
       max = calc.max(max, dom.at(i).at(1))
     }
+    if min == max {
+      min -= float-epsilon
+      max += float-epsilon
+    }
     ptx.axes.at(ax.name).auto-domain = (min, max)
   }
   return ptx

src/projection.typ

@@ -1,3 +1,4 @@
+#import "/src/cetz.typ": vector
 
 /// Create a new cartesian projection between two vectors, low and high
 ///
@@ -23,19 +24,24 @@
   )
 }
 
-/// - center (vector): Center vector
-/// - start (angle): Start angle (0deg for full circle)
+/// - low (vector): low vector
+/// - high (angle): Start angle (0deg for full circle)
 /// - stop (angle): Stop angle (360deg for full circle)
-/// - theta (axis): Theta axis
-/// - r (axis): R axis
+/// - axes (list): Axis array (angular, distal)
 /// -> function Transformation for one or more vectors
-#let polar(center, radius, start, stop, theta, r) = {
+#let polar(low, high, (angular, distal, ..), start: 0deg, stop: 360deg) = {
+  let center = vector.lerp(low, high, .5)
+  let radius = calc.min(..vector.sub(high, low).slice(0, 2)) / 2
+
   return (
-    axes: axes,
+    axes: (angular, distal),
     transform: (..v) => {
-      let v = v.pos()
-      // TODO
-      return v
+      return v.pos().map(v => {
+        let theta = (angular.transform)(angular, v.at(0), start, stop)
+        let r = (distal.transform)(distal, v.at(1), 0, radius)
+
+        vector.add(center, (calc.cos(theta) * r, calc.sin(theta) * r, 0))
+      })
     },
   )
 }

src/spine.typ

@@ -106,6 +106,14 @@
       ),
     ),
   ),
+  distal: (
+    tick: (
+      flip: true,
+      label: (
+        anchor: "east",
+      )
+    )
+  ),
 )
 
 /// Default schoolbook style
@@ -160,9 +168,9 @@
 
 
 ///
-#let cartesian-scientific(projections: none, style: (:)) = {
+#let cartesian-scientific(projections: none, name: none, style: (:)) = {
   return (
-    name: none,
+    name: name,
     draw: (ptx) => {
       let proj = projections.at(0)
       let axes = proj.axes
@@ -224,9 +232,9 @@
 }
 
 ///
-#let schoolbook(projections: none, zero: (0, 0), ..style) = {
+#let schoolbook(projections: none, name: none, zero: (0, 0), ..style) = {
   return (
-    name: none,
+    name: name,
     draw: (ptx) => {
       let proj = projections.at(0)
       let axes = proj.axes
@@ -288,3 +296,41 @@
     }
   )
 }
+
+/// Polar frame
+#let polar(projections: none, name: none, ..style) = {
+  assert(projections.len() == 1,
+    message: "Unexpected number of projections!")
+
+  return (
+    name: name,
+    draw: (ptx) => {
+      let proj = projections.first()
+      let angular = proj.axes.at(0)
+      let distal = proj.axes.at(1)
+
+      let (origin, outer) = (proj.transform)((0, distal.min), (0, distal.max))
+      let radius = vector.dist(origin, outer)
+
+      let style = _prepare-style(ptx, cetz.styles.resolve(ptx.cetz-ctx.style,
+        root: "axes", merge: style.named(), base: default-style))
+      let angular-style = _get-axis-style(ptx, style, "angular")
+      let distal-style = _get-axis-style(ptx, style, "distal")
+
+      let r-start = origin
+      let r-end = vector.add(origin, (0, radius))
+      draw.line(r-start, r-end, stroke: distal-style.stroke)
+      if "computed-ticks" in distal {
+        //ticks.draw-cartesian-grid(min-y, max-y, 1, y, y.computed-ticks, min-x, max-x, y-style)
+        ticks.draw-cartesian(r-start, r-end, distal.computed-ticks, distal-style)
+      }
+
+      let padding = angular-style.padding.first()
+      draw.circle(origin, radius: radius + padding,
+        stroke: angular-style.stroke)
+      if "computed-ticks" in angular {
+        // TODO
+      }
+    },
+  )
+}