add gun-tackle (#47)

* add gun-tackle

* add myself to citation.cff, remove extra quote

* minor refactor

* assets

---------

Co-authored-by: Janosh Riebesell <[email protected]>

Author: SillyFreak

assets/gun-tackle/gun-tackle-hd.png

@@ -0,0 +1,118 @@
+#import "@preview/cetz:0.3.4"
+#import "@preview/pull-eh:0.1.0"
+#import cetz.draw: on-layer, line, content
+#import pull-eh: wind, ccw, cw
+
+#set page(width: auto, height: auto, margin: 5mm)
+#set text(0.9em)
+
+#let block(coord, (w, h), ..args) = {
+  // use the given coord as the center of the rect
+  let tl = (rel: (-w / 2, -h / 2), to: coord)
+  let br = (rel: (w, h))
+  cetz.draw.rect(tl, br, fill: white, ..args)
+}
+#let fixing(coord, len, ..args) = {
+  cetz.draw.line(stroke: 3pt, coord, (rel: len, to: coord))
+  cetz.draw.circle(coord, fill: black, radius: 0.2)
+}
+#let pulley(..args) = {
+  cetz.draw.circle(fill: green, stroke: none, ..args)
+}
+
+#let force(coord, direction, ..args) = {
+  let mark = (end: (symbol: ">", length: 0.12cm, width: 0.15cm))
+  cetz.draw.line(coord, (rel: direction), stroke: 4pt, mark: mark, ..args)
+}
+
+#let gun-tackle = cetz.canvas({
+  // the pulleys; on the default layer
+  pulley(name: "pulley1", (1, 4))
+  pulley(name: "pulley2", (1, 0))
+  // the "fixed" parts of the diagram: ceiling and blocks. The blocks wrap around the pulleys
+  // and thus hide them and the rope
+  on-layer(
+    1,
+    {
+      block(name: "block1", "pulley1", (0.4, 2.4))
+      block(name: "block2", "pulley2", (0.4, 2.4))
+      line(stroke: 2pt, (rel: (-1.4, 0), to: "block1.north"), (rel: (1.4, 0), to: "block1.north"))
+    },
+  )
+  // the rope; drawn over the pulleys, but hidden by the blocks
+  wind(
+    stroke: 1.5pt,
+    (rel: (1.5, -2.5), to: "pulley1"),
+    (coord: "pulley1", radius: 1) + ccw,
+    (coord: "pulley2", radius: 1) + ccw,
+    "block1.south",
+  )
+  // the labels of the diagram
+  on-layer(
+    1,
+    {
+      content((rel: (-1.4, -2), to: "pulley1"))[50N]
+      content((rel: (-0.1, -2), to: "pulley1"))[50N]
+      content((rel: (1.7, -1.5), to: "pulley1"))[50N]
+
+      force((rel: (0, 0.4), to: "pulley1.north"), (90deg, 0.8), name: "f-ceiling")
+      content((rel: (0.7, 0), to: "f-ceiling"))[150N]
+
+      force((rel: (0, -0.4), to: "pulley2.south"), (-90deg, 0.8), name: "f-load")
+      content((rel: (0.7, 0), to: "f-load"))[100N]
+
+      force((rel: (1.54, -2.7), to: "pulley1"), (-78deg, 0.8), name: "f-rope")
+      content((rel: (0.65, 0), to: "f-rope"))[50N]
+    },
+  )
+})
+
+#let separated = cetz.canvas({
+  let block1 = (4, 5.2)
+
+  // the pulleys; on the default layer
+  pulley(name: "pulley1", (1, 4))
+  pulley(name: "pulley2", (3, 0))
+  // the "fixed" parts of the diagram: ceiling and blocks. The blocks wrap around the pulleys
+  // and thus hide them and the rope
+  on-layer(
+    1,
+    {
+      fixing("pulley1.center", (0, 1.2))
+      fixing("pulley2.center", (0, -1.2))
+      line(stroke: 2pt, (rel: (-4.4, 0), to: block1), (rel: (0.4, 0), to: block1))
+    },
+  )
+  // the rope; drawn over the pulleys, but hidden by the blocks
+  wind(
+    stroke: 1.5pt,
+    (rel: (-1.5, -2.5), to: "pulley1"),
+    (coord: "pulley1", radius: 1) + cw,
+    (coord: "pulley2", radius: 1) + ccw,
+    block1,
+  )
+  // the labels of the diagram
+  on-layer(
+    1,
+    {
+      content((rel: (3.4, -2), to: "pulley1"))[50N]
+      content((rel: (1.4, -2), to: "pulley1"))[50N]
+      content((rel: (-1.7, -1.5), to: "pulley1"))[50N]
+
+      force((rel: (1.5, 0.4), to: "pulley1.north"), (90deg, 0.8), name: "f-ceiling")
+      content((rel: (0.7, 0), to: "f-ceiling"))[150N]
+
+      force((rel: (0, -0.4), to: "pulley2.south"), (-90deg, 0.8), name: "f-load")
+      content((rel: (0.7, 0), to: "f-load"))[100N]
+
+      force((rel: (-1.54, -2.7), to: "pulley1"), (-102deg, 0.8), name: "f-rope")
+      content((rel: (0.65, 0), to: "f-rope"))[50N]
+    },
+  )
+})
+
+#grid(
+  columns: 2,
+  column-gutter: 2cm,
+  gun-tackle, separated,
+)