add [r, g, b] field to triangle, so we can draw coloured objects (next: add ability to change current colour)

functional-core/app/app-update.sml

@@ -246,7 +246,7 @@ struct
         end
     | NO_TRIANGLE =>
         (case #triangles model of
-           {x1, y1, x2, y2, x3, y3} :: trianglesTl =>
+           {x1, y1, x2, y2, x3, y3, r, g, b} :: trianglesTl =>
              (* Have to slice off (x3, y3) from triangle head,
               * turn (x1, y1, x2, y2) into a triangleStage,
               * and redraw both triangle and triangleStage. *)
@@ -309,9 +309,19 @@ struct
          | SECOND {x1, y1, x2, y2} =>
              (* clear triangle stage, add to trinagle list and redraw triangles *)
              let
+               val {r, g, b, ...} = model
                val newTriangleStage = NO_TRIANGLE
                val newTriangle =
-                 {x1 = x1, y1 = y1, x2 = x2, y2 = y2, x3 = x, y3 = y}
+                 { x1 = x1
+                 , y1 = y1
+                 , x2 = x2
+                 , y2 = y2
+                 , x3 = x
+                 , y3 = y
+                 , r = r
+                 , g = g
+                 , b = b
+                 }
                val newTriangles = newTriangle :: (#triangles model)
                val model =
                  AppWith.redo (model, newTriangleStage, newTriangles, redoHd)