Fix bug with knot mesh not closing loop, tweak constants

Torus.elm

@@ -34,6 +34,11 @@ type alias Model =
     , time : Float
     , winSize : Window.Size }
 
+totalLinePoints = 250
+ringRadius = 0.1
+ringVerts = 40
+knotScale = 0.2
+
 init: ( Model , Cmd Msg )
 init =
     -- ( { p = 1 , q = 0 , time = 0.0 , winSize = (Window.Size 1 1)
@@ -124,10 +129,10 @@ torusPoints p q =
     interpolatedCircle totalLinePoints
     |> List.map
         (\ t ->
-            let r = 0.5 * (2 + sin (q * t))
+            let r = 2 + sin (q * t)
             in vec3
                  (cos (t * p) * r)
-                 (cos (t * q) * r * 0.5)
+                 (cos (t * q) * r * 0.25)
                  (sin (t * p) * r) )
 
 
@@ -136,9 +141,11 @@ torusRings verts =
     verts
     |> List.map
         (\ (p1, p2)->
-            (List.map circlePoint <| interpolatedCircle ringVerts)
+            ringVerts
+            |> interpolatedCircle
+            |> List.map circlePoint
             |> List.map (\ p ->
-                let (mid , dir) = (Vec3.add p1 p2 |> Vec3.scale 0.5 , Vec3.sub p2 p1 |> Vec3.normalize)
+                let (mid , dir) = (Vec3.add p1 p2 |> Vec3.scale knotScale , Vec3.sub p2 p1 |> Vec3.normalize)
                     p_ = Vec3.toRecord p
                     dir_ = Vec3.toRecord dir
                     u = Vec3.cross dir Vec3.j |> Vec3.normalize
@@ -168,7 +175,12 @@ circlePoint: Float -> Vec3
 circlePoint x = vec3 (cos x) (sin x) 0
 
 makePairs: List a -> List (a ,a)
-makePairs ps = List.map2 (,) ps (List.drop 1 ps)
+makePairs ps1 =
+    case ps1 of
+    [] -> []
+    h::tail ->
+        let ps2 = tail ++ [h]
+        in List.map2 (,) ps1 ps2
 
 closedPairs: List a -> List (a ,a)
 closedPairs xs =
@@ -197,6 +209,10 @@ colorToVec3 color =
         c = Color.toRgb color
     in vec3 (to01 c.red) (to01 c.green) (to01 c.blue)
 
+-------------
+-- Shaders
+-------------
+
 type alias DiffuseColor =
     { projection : Mat4
     , view : Mat4
@@ -248,6 +264,3 @@ diffuseFS =
             gl_FragColor = vec4(color * vlightWeight, 1.0);
         }
     |]
-
-
-