Add 'dotscape/' from commit 'f306501a68a51b634e895c5fdac70788ae899d75'

git-subtree-dir: dotscape
git-subtree-mainline: 6b91d64fc3
git-subtree-split: f306501a68

dotscape/fcore/ndc.sml

@@ -0,0 +1,38 @@
+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 (startX, startY, endX, endY, r, g, b) =
+    #[ startX, endY, r, g, b
+     , endX, endY, r, g, b
+     , startX, startY, r, g, b
+
+     , startX, startY, r, g, b
+     , endX, endY, r, g, b
+     , endX, startY, r, g, b
+     ]
+
+  fun fromPixelX (xpos, windowWidth, windowHeight) =
+    let
+      val halfWidth = Real32.fromInt windowWidth / 2.0
+    in
+      (xpos - halfWidth) / halfWidth
+    end
+
+  fun fromPixelY (ypos, windowWidth, windowHeight) =
+    let
+      val halfHeight = Real32.fromInt windowHeight / 2.0
+    in
+      ~((ypos - halfHeight) / halfHeight)
+    end
+end