begin coding player

fcore/player.sml

@@ -0,0 +1,57 @@
+structure Player =
+struct
+  datatype y_axis = ON_GROUND | FALLING | JUMPING of int
+  datatype x_axis = MOVE_LEFT | STAY_STILL | MOVE_RIGHT
+
+  (* width/height *)
+  val size = 35
+
+  val moveBy = 5
+  val jumpLimit = 55
+
+  type t = {yAxis: y_axis, xAxis: x_axis, health: int, x: int, y: int}
+
+  fun mkPlayer (health, xAxis, yAxis, x, y) =
+    {yAxis = yAxis, xAxis = xAxis, health = health, x = x, y = y}
+
+  fun move (player: t) =
+    let
+      val {yAxis, xAxis, x, y, health} = player
+
+      (* todo: check for wall and platform collisions 
+       * in case analysis for both axis
+       * *)
+      val x =
+        case xAxis of
+          MOVE_LEFT =>
+            (* todo: check if we are trying to move left 
+             * even though player is against wall.
+             * In that case, keep same action (it is a sign for us to animate),
+             * but don't actually move leftwards. *)
+            x - moveBy
+        | MOVE_RIGHT => (* todo: check against wall *) x + moveBy
+        | STAY_STILL => x
+    in
+      case yAxis of
+        JUMPING jumped =>
+          (* check if we hit jump limit; 
+           * if we did, change to falling case. 
+           * *)
+          if jumped + moveBy <= jumpLimit then
+            let
+              val jumped = jumped + moveBy
+              val yAxis = JUMPING jumped
+              val y = y + moveBy
+            in
+              mkPlayer (health, xAxis, yAxis, x, y)
+            end
+          else
+            mkPlayer (health, xAxis, FALLING, x, y)
+      | FALLING =>
+          (* todo: keep decrementing and falling down 
+           * until we hit ground or platform 
+           * *)
+          mkPlayer (health, xAxis, yAxis, x, y - moveBy)
+      | ON_GROUND => mkPlayer (health, xAxis, yAxis, x, y)
+    end
+end