start taking in account feedbacks

slides/lib.typ

@@ -19,6 +19,8 @@ rgb("#E69426"),
 pirat-color.red,
 )
 
+#let etal = [_et al._]
+
 #let highlight-block(body) = {
   set text(fill: white)
   block(
@@ -73,22 +75,8 @@ pirat-color.red,
 }
 */
 
-#let ghost(
-  img, x: 0pt, 
-  y: 0pt,
-  mirror: false,
-  rot: 0deg,
-  height: 100pt
-) = context {
-  let img = image(img, height: height)
-  if mirror {
-    img = scale(x: -100%, img)
-  }
-  if rot != 0deg {
-    img = rotate(rot, img)
-  }
-
-  let s = measure(img)
+#let place-fg(x: 0pt, y: 0pt, body) = context {
+  let s = measure(body)
   let hx = s.width / 2
   let hy = s.height / 2
 
@@ -96,10 +84,27 @@ pirat-color.red,
     bottom + left,
     dx: x - hx,
     dy: -y + hy,
-    img
+    body
   )
 }
 
+#let ghost(
+  img, x: 0pt, 
+  y: 0pt,
+  mirror: false,
+  rot: 0deg,
+  height: 100pt
+) = {
+  let img = image(img, height: height)
+  if mirror {
+    img = scale(x: -100%, img)
+  }
+  if rot != 0deg {
+    img = rotate(rot, img)
+  }
+  place-fg(x: x, y: y, img)
+}
+
 #let ghost-1 = ghost.with("imgs/ghosts/ghost-1.png")
 #let ghost-2 = ghost.with("imgs/ghosts/ghost-2.png")
 #let ghost-3 = ghost.with("imgs/ghosts/ghost-3.png")
@@ -111,3 +116,30 @@ pirat-color.red,
 #let eye-2 = ghost.with("imgs/ghosts/eye-2.png")
 #let eye-3 = ghost.with("imgs/ghosts/eye-3.png")
 #let eye-4 = ghost.with("imgs/ghosts/eye-4.png")
+
+#let arrow(start, end, strk: 3pt + black) = {
+  let strk = stroke(strk)
+  start.at(1) = -start.at(1)
+  end.at(1) = -end.at(1)
+  let (xe, ye) = end
+  let (xs, ys) = start
+  let w = xe.pt() - xs.pt()
+  let h = ye.pt() - ys.pt()
+  let len = if w == 0pt and h == 0pt {
+    1pt
+  } else {
+    calc.sqrt(w*w + h*h)
+  }
+  let cos = w / len
+  let sin = h / len
+
+  place(bottom + left, line(start: start, end: end, stroke: strk))
+  place(bottom + left, polygon(
+    fill: strk.paint,
+    stroke: strk,
+    end,
+    (xe + strk.thickness * (sin - cos), ye - strk.thickness * (sin + cos )),
+    (xe - strk.thickness * (sin + cos), ye - strk.thickness * (sin - cos )),
+  ))
+}
+