change Ndc.fromPixelX and Ndc.fromPixelY functions to not try and centre pixels (centering is handled in the click points instead)

fcore/ndc.sml

@@ -24,33 +24,17 @@ struct
 
   fun fromPixelX (xpos, windowWidth, windowHeight) =
     let
-      val halfWidth = Real32.fromInt (windowWidth div 2)
+      val halfWidth = Real32.fromInt windowWidth / 2.0
       val xpos = xpos - halfWidth
     in
-      if windowWidth > windowHeight then
+      xpos / halfWidth
-        let
-          val difference = windowWidth - windowHeight
-          val offset = Real32.fromInt (difference div 2)
-        in
-          xpos / (halfWidth - offset)
-        end
-      else
-        xpos / halfWidth
     end
 
   fun fromPixelY (ypos, windowWidth, windowHeight) =
     let
-      val halfHeight = Real32.fromInt (windowHeight div 2)
+      val halfHeight = Real32.fromInt windowHeight / 2.0
       val ypos = ~(ypos - halfHeight)
     in
-      if windowHeight > windowWidth then
+      ypos / halfHeight
-        let
-          val difference = windowHeight - windowWidth
-          val offset = Real32.fromInt (difference div 2)
-        in
-          ypos / (halfHeight - offset)
-        end
-      else
-        ypos / halfHeight
     end
 end