figure out reason for the strange player/projectile alignment, and address it (when player is facing left, we want to subtract size of whole projectile so it looks like it starts at the leftmost side; however, when player is facing right, we want to add by the width of the player, so it looks like the projectile starts from the player's rightmost side)

fcore/level/player/player-vec.sml

@@ -155,8 +155,9 @@ struct
                val playerVec = PlayerAttackStandRight.lerp
                  (rx, ry, 3.0, windowWidth, windowHeight)
 
-               (* todo: why does 81 work to give perfect alignment? *)
-               val projX = x + 81
+               (* adding playerWidth to x so that projectile starts from 
+                * the rightmost pixel of the player *)
+               val projX = x + Constants.playerWidth
                val projY = y + (Constants.playerHeight div 3)
                val projX = (Real32.fromInt projX + xOffset) * ratio
                val projY = (Real32.fromInt projY + yOffset) * ratio
@@ -172,6 +173,10 @@ struct
                val playerVec = PlayerAttackStandLeft.lerp
                  (rx, ry, 3.0, windowWidth, windowHeight)
 
+               (* subtracting playerHeight from x because projectile
+                * is the same size as the playerHeight, and it looks like
+                * the projectile starts from player's leftmost side this way.
+                * *)
                val projX = x - Constants.playerHeight
                val projY = y + (Constants.playerHeight div 3)
                val projX = (Real32.fromInt projX + xOffset) * ratio