waves: Use ortho function (#785)

gallery/waves.typ

@@ -5,35 +5,36 @@
 #canvas({
   import draw: *
 
-  // Set up the transformation matrix
-  set-transform(matrix.transform-rotate-dir((1, 1, -1.3), (0, 1, .3)))
-  scale(x: 1.5, z: -1)
+  ortho(y: -30deg, x: 30deg, {
+    on-xz({
+      grid((0,-2), (8,2), stroke: gray + .5pt)
+    })
 
-  grid((0,-2), (8,2), stroke: gray + .5pt)
+    // Draw a sine wave on the xy plane
+    let wave(amplitude: 1, fill: none, phases: 2, scale: 8, samples: 100) = {
+      line(..(for x in range(0, samples + 1) {
+        let x = x / samples
+        let p = (2 * phases * calc.pi) * x
+        ((x * scale, calc.sin(p) * amplitude),)
+      }), fill: fill)
 
-  // Draw a sine wave on the xy plane
-  let wave(amplitude: 1, fill: none, phases: 2, scale: 8, samples: 100) = {
-    line(..(for x in range(0, samples + 1) {
-      let x = x / samples
-      let p = (2 * phases * calc.pi) * x
-      ((x * scale, calc.sin(p) * amplitude),)
-    }), fill: fill)
-
-    let subdivs = 8
-    for phase in range(0, phases) {
-      let x = phase / phases
-      for div in range(1, subdivs + 1) {
-        let p = 2 * calc.pi * (div / subdivs)
-        let y = calc.sin(p) * amplitude
-        let x = x * scale + div / subdivs * scale / phases
-        line((x, 0), (x, y), stroke: rgb(0, 0, 0, 150) + .5pt)
+      let subdivs = 8
+      for phase in range(0, phases) {
+        let x = phase / phases
+        for div in range(1, subdivs + 1) {
+          let p = 2 * calc.pi * (div / subdivs)
+          let y = calc.sin(p) * amplitude
+          let x = x * scale + div / subdivs * scale / phases
+          line((x, 0), (x, y), stroke: rgb(0, 0, 0, 150) + .5pt)
+        }
       }
     }
-  }
 
-  group({
-    rotate(x: 90deg)
-    wave(amplitude: 1.6, fill: rgb(0, 0, 255, 50))
+    on-xy({
+      wave(amplitude: 1.6, fill: rgb(0, 0, 255, 50))
+    })
+    on-xz({
+      wave(amplitude: 1, fill: rgb(255, 0, 0, 50))
+    })
   })
-  wave(amplitude: 1, fill: rgb(255, 0, 0, 50))
 })