begin parameterising level so that it fits into larger type (with different modes like TITLE, LEVEL, SETTINGS, etc.)

fcore/level/projectile.sml

@@ -0,0 +1,58 @@
+structure Projectile =
+struct
+  fun helpGetProjectileVec
+    (pos, projectiles, width, height, ratio, xOffset, yOffset, acc) =
+    if pos = Vector.length projectiles then
+      Vector.concat acc
+    else
+      let
+        val {x, y, ...} = Vector.sub (projectiles, pos)
+
+        val x = Real32.fromInt x * ratio + xOffset
+        val y = Real32.fromInt y * ratio + yOffset
+
+        val size = Constants.projectileSize * ratio
+
+        val vec = Field.lerp
+          (x, y, size, size, width, height, 0.3, 0.9, 0.3, 1.0)
+        val acc = vec :: acc
+      in
+        helpGetProjectileVec
+          (pos + 1, projectiles, width, height, ratio, xOffset, yOffset, acc)
+      end
+
+  fun getProjectileVec (player: PlayerType.player, width, height) =
+    let
+      val {projectiles, ...} = player
+
+      val wratio = width / 1920.0
+      val hratio = height / 1080.0
+    in
+      if wratio < hratio then
+        let
+          val scale = 1080.0 * wratio
+          val yOffset =
+            if height > scale then (height - scale) / 2.0
+            else if height < scale then (scale - height) / 2.0
+            else 0.0
+
+          val xOffset = 0.0
+        in
+          helpGetProjectileVec
+            (0, projectiles, width, height, wratio, xOffset, yOffset, [])
+        end
+      else
+        let
+          val scale = 1920.0 * hratio
+          val xOffset =
+            if width > scale then (width - scale) / 2.0
+            else if width < scale then (scale - width) / 2.0
+            else 0.0
+
+          val yOffset = 0.0
+        in
+          helpGetProjectileVec
+            (0, projectiles, width, height, hratio, xOffset, yOffset, [])
+        end
+    end
+end