add functionality to draw in different colours

fcore/quad-tree.sml

@@ -99,10 +99,7 @@ end
 
 structure CollisionTree =
 struct
-  (* ignoreData = any data we find in grid but which doesn't concern us
-   * so we omit from tree, to reduce number of items in tree,
-   * and therefore decrease the constant in O(n) *)
-  val ignoreData = 0
+  fun shouldIgnoreData {a, r = _, g = _, b = _} = a = 0
 
   local
     fun loopYAxis (x, y, eX, eY, yAxis, col) =
@@ -147,7 +144,7 @@ struct
         val yAxis = Vector.sub (grid, x)
         val data = Vector.sub (yAxis, y)
       in
-        if data = ignoreData then
+        if shouldIgnoreData data then
           bintree
         else
           let
@@ -218,8 +215,14 @@ struct
       val endX = Ndc.fromPixelX (ex, windowWidth, windowHeight)
       val startY = Ndc.fromPixelY (y, windowWidth, windowHeight)
       val endY = Ndc.fromPixelY (ey, windowWidth, windowHeight)
+
+      val {r, g, b, a} = data
+      val r = Real32.fromInt r / 255.0
+      val g = Real32.fromInt g / 255.0
+      val b = Real32.fromInt b / 255.0
+      val a = Real32.fromInt a / 255.0
     in
-      Ndc.ltrbToVertexRgb (startX, startY, endX, endY, 0.0, 0.0, 0.0) :: acc
+      Ndc.ltrbToVertexRgb (startX, startY, endX, endY, r, g, b) :: acc
     end
 
   fun toTriangles
@@ -250,7 +253,7 @@ struct
 
   (* building and querying quad tree, plus compression *)
   datatype quad_tree =
-    LEAF of {x: int, y: int, ex: int, ey: int, data: int}
+    LEAF of {x: int, y: int, ex: int, ey: int, data: AppType.square}
   | NODE of {tl: quad_tree, tr: quad_tree, bl: quad_tree, br: quad_tree}
   | EMPTY
 
@@ -278,7 +281,7 @@ struct
         val yAxis = Vector.sub (grid, x)
         val data = Vector.sub (yAxis, y)
       in
-        if data = ignoreData then
+        if shouldIgnoreData data then
           EMPTY
         else
           let