begin merging files which were previously in temp-squares directory into main

fcore/ndc.sml

@@ -0,0 +1,56 @@
+structure Ndc = 
+struct
+  (* ndc = normalised device coordinates *)
+
+  fun ltrbToVertex (left, top, right, bottom) =
+    #[ left, bottom
+     , right, bottom
+     , left, top
+
+     , left, top
+     , right, bottom
+     , right, top
+     ]
+
+  fun ltrbToVertexRgb (left, top, right, bottom, r, g, b) =
+    #[ left, bottom, r, g, b
+     , right, bottom, r, g, b
+     , left, top, r, g, b
+
+     , left, top, r, g, b
+     , right, bottom, r, g, b
+     , right, top, r, g, b
+     ]
+
+  fun fromPixelX (xpos, windowWidth, windowHeight) =
+    let
+      val halfWidth = Real32.fromInt (windowWidth div 2)
+      val xpos = xpos - halfWidth
+    in
+      if windowWidth > windowHeight then
+        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 ypos = ~(ypos - halfHeight)
+    in
+      if windowHeight > windowWidth then
+        let
+          val difference = windowHeight - windowWidth
+          val offset = Real32.fromInt (difference div 2)
+        in
+          ypos / (halfHeight - offset)
+        end
+      else
+        ypos / halfHeight
+    end
+end