Make rotations/angles consistent (#275)

Closes #274.

src/draw/shapes.typ

@@ -495,7 +495,7 @@
   } else if args.len() == 3 {
     args
   } else {
-    panic("Expected 2 or 3 positional arguments, got " + str(args.len))
+    panic("Expected 2 or 3 positional arguments, got " + str(args.len()))
   }
 
   coordinate.resolve-system(a)
@@ -530,6 +530,8 @@
       angle
     }
 
+    // Typst's `rotate` function is clockwise relative to x-axis, which is backwards from us
+    angle = angle * -1
 
     let (width, height, ..) = if auto-size {
       util.measure(ctx, body)

src/lib/angle.typ

@@ -54,9 +54,9 @@
     message: "Angle z coordinates of all three points must be equal")
 
   let (s, e, ss) = {
-    let s = vector.angle2(origin, a) * -1
+    let s = vector.angle2(origin, a)
     if s < 0deg { s += 360deg }
-    let e = vector.angle2(origin, b) * -1
+    let e = vector.angle2(origin, b)
     if e < 0deg { e += 360deg }
 
     if s > e {

src/lib/axes.typ

@@ -422,7 +422,7 @@
       if not axis.at("is-mirror", default: false) {
         let is-left-right = side in ("west", "east")
         let angle = if is-left-right {
-          -90deg
+          90deg
         } else {
           0deg
         }

src/lib/decorations.typ

@@ -280,7 +280,7 @@
     // pointing upwards, so we set the origin and rotate the entire group accordingly
     let (_, start, end) = coordinate.resolve(ctx, start, end)
     set-origin(start)
-    rotate(vector.angle2(start, end))
+    rotate(vector.angle2(start, end) * -1)
 
     let length = vector.dist(start, end)
     let middle = aspect * length

src/vector.typ

@@ -89,7 +89,8 @@
 
 /// Calculate angle between two points and the x-axis in 2d space
 #let angle2(a, b) = {
-  return calc.atan2(a.at(1) - b.at(1), a.at(0) - b.at(0)) + 90deg
+  // Typst's atan2 is (x, y) order, not (y, x)
+  return calc.atan2(b.at(0) - a.at(0), b.at(1) - a.at(1))
 }
 
 /// Calculate angle between three points 

tests/axes/test.typ

@@ -23,10 +23,10 @@
   set-style(axes: (stroke: blue))
   set-style(axes: (left: (tick: (stroke: green + 2pt))))
   set-style(axes: (bottom: (tick: (stroke: red, length: .5,
-                                   label: (angle: -90deg,
+                                   label: (angle: 90deg,
                                            anchor: "east")))))
   set-style(axes: (right: (tick: (label: (offset: .2,
-                                          angle: 45deg,
+                                          angle: -45deg,
                                           anchor: "north-west"), length: -.1))))
   axes.scientific(size: (6, 6),
     frame: "set",