From 859d0e35456b35309397fe75ecd262edcf5ecbe6 Mon Sep 17 00:00:00 2001
From: Ian Mackenzie <ian.e.mackenzie@gmail.com>
Date: Wed, 11 Nov 2020 19:58:07 -0500
Subject: [PATCH] Add example of reproducing circle with quadratic NURBS curve

---
 sandbox/src/NurbsCircle.elm | 60 +++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 sandbox/src/NurbsCircle.elm

diff --git a/sandbox/src/NurbsCircle.elm b/sandbox/src/NurbsCircle.elm
new file mode 100644
index 00000000..06bdd5ba
--- /dev/null
+++ b/sandbox/src/NurbsCircle.elm
@@ -0,0 +1,60 @@
+module NurbsCircle exposing (main)
+
+import Circle2d
+import Color
+import Drawing2d
+import Html exposing (Html)
+import Pixels
+import Point2d
+import Polyline2d
+import Quantity
+import RationalQuadraticSpline2d
+import Rectangle2d
+
+
+main : Html Never
+main =
+    let
+        circle =
+            Circle2d.withRadius (Pixels.float 300) Point2d.origin
+
+        w =
+            1 / sqrt 2
+
+        splineSegments =
+            RationalQuadraticSpline2d.bSplineSegments
+                [ 0, 0, 1, 1, 2, 2, 3, 3, 4, 4 ]
+                [ ( Point2d.pixels 300 0, 1 )
+                , ( Point2d.pixels 300 300, w )
+                , ( Point2d.pixels 0 300, 1 )
+                , ( Point2d.pixels -300 300, w )
+                , ( Point2d.pixels -300 0, 1 )
+                , ( Point2d.pixels -300 -300, w )
+                , ( Point2d.pixels 0 -300, 1 )
+                , ( Point2d.pixels 300 -300, w )
+                , ( Point2d.pixels 300 0, 1 )
+                ]
+
+        polylines =
+            List.map (RationalQuadraticSpline2d.segments 100) splineSegments
+    in
+    Drawing2d.toHtml
+        { viewBox =
+            Rectangle2d.from
+                (Point2d.pixels -400 -400)
+                (Point2d.pixels 400 400)
+        , size = Drawing2d.fixed
+        }
+        []
+        [ Drawing2d.group
+            [ Drawing2d.strokeColor Color.lightBlue
+            , Drawing2d.strokeWidth (Pixels.float 6)
+            ]
+            (List.map (Drawing2d.polyline []) polylines)
+        , Drawing2d.circle
+            [ Drawing2d.strokeColor Color.orange
+            , Drawing2d.strokeWidth (Pixels.float 2)
+            , Drawing2d.noFill
+            ]
+            circle
+        ]