Adding Box Frame as a primitive.

Adding a box frame primitive, and associated test.

Graphics/Implicit/Canon.hs

@@ -90,7 +90,7 @@ import Graphics.Implicit.Definitions
       , RotateExtrude
       , Shared3
       , Sphere
-      , Transform3
+      , Transform3, BoxFrame
       )
   , hasZeroComponent
   )
@@ -171,6 +171,7 @@ fmapObj3
 fmapObj3 f _ _ (Cube v) = f $ Cube v
 fmapObj3 f _ _ (Sphere r) = f $ Sphere r
 fmapObj3 f _ _ (Cylinder r1 r2 h) = f $ Cylinder r1 r2 h
+fmapObj3 f _ _ (BoxFrame b e) = f $ BoxFrame b e
 fmapObj3 f g s (Rotate3 q o) = f $ Rotate3 q (fmapObj3 f g s o)
 fmapObj3 f g s (Transform3 m o) = f $ Transform3 m (fmapObj3 f g s o)
 fmapObj3 f g s (Extrude o2 h) = f $ Extrude (fmapObj2 g f s o2) h
@@ -226,6 +227,7 @@ instance EqObj SymbolicObj3 where
   Cube a =^= Cube b = a == b
   Sphere a =^= Sphere b = a == b
   Cylinder r1a r2a ha =^= Cylinder r1b r2b hb = r1a == r1b && r2a == r2b && ha == hb
+  BoxFrame b1 e1 =^= BoxFrame b2 e2 = b1 == b2 && e1 == e2
   Rotate3 x a =^= Rotate3 y b = x == y && a =^= b
   Transform3 x a =^= Transform3 y b = x == y && a =^= b
   Extrude a x =^= Extrude b y = x == y && a =^= b
@@ -299,6 +301,7 @@ canon3 :: SymbolicObj3 -> SymbolicObj3
 canon3 (Cube v) | hasZeroComponent v = emptySpace
 canon3 (Sphere 0) = emptySpace
 canon3 (Cylinder 0 _ _) = emptySpace
+canon3 (BoxFrame _ 0) = emptySpace
 canon3 (Extrude _o2 0) = emptySpace
 canon3 (Rotate3 0 o) = o
 canon3 (RotateExtrude 0 _t _r _o) = emptySpace

Graphics/Implicit/Definitions.hs

@@ -58,6 +58,7 @@ module Graphics.Implicit.Definitions (
         Cylinder,
         Rotate3,
         Transform3,
+        BoxFrame,
         Extrude,
         ExtrudeM,
         ExtrudeOnEdgeOf,
@@ -324,6 +325,7 @@ data SymbolicObj3 =
       Cube ℝ3 -- rounding, size.
     | Sphere ℝ -- radius
     | Cylinder ℝ ℝ ℝ --
+    | BoxFrame ℝ3 ℝ -- b e from https://iquilezles.org/articles/distfunctions/
     -- Simple transforms
     | Rotate3 (Quaternion ℝ) SymbolicObj3
     | Transform3 (M44 ℝ) SymbolicObj3
@@ -351,6 +353,7 @@ instance Show SymbolicObj3 where
     -- centered.
     Cube sz -> showCon "cube" @| False @| sz
     Sphere d -> showCon "sphere" @| d
+    BoxFrame b e -> showCon "boxFrame" @| b @| e
     -- NB: The arguments to 'Cylinder' are backwards compared to 'cylinder' and
     -- 'cylinder2'.
     Cylinder h r1 r2 | r1 == r2 ->

Graphics/Implicit/Export/RayTrace.hs

@@ -3,7 +3,7 @@
 -- Copyright 2016, Julia Longtin ([email protected])
 -- Released under the GNU AGPLV3+, see LICENSE
 
-module Graphics.Implicit.Export.RayTrace( Color(Color), average, Camera(Camera), Light(Light), Scene(Scene), traceRay, cameraRay) where
+module Graphics.Implicit.Export.RayTrace( Color(Color), average, Camera(Camera), Light(Light), Scene(Scene), traceRay, cameraRay, vectorDistance) where
 
 import Prelude(Show, RealFrac, Maybe(Just, Nothing), Bool(False, True), (-), (.), ($), (*), (/), min, fromInteger, max, round, fromIntegral, unzip, fmap, length, sum, maximum, minimum, (>), (+), (<), (==), pred, flip, not, abs, floor, toRational, otherwise, pure)
 

Graphics/Implicit/Export/SymbolicFormats.hs

@@ -12,7 +12,7 @@ module Graphics.Implicit.Export.SymbolicFormats (scad2, scad3) where
 
 import Prelude((.), fmap, Either(Left, Right), ($), (*), ($!), (-), (/), pi, error, (+), (==), take, floor, (&&), const, pure, (<>), sequenceA, (<$>))
 
-import Graphics.Implicit.Definitions(ℝ, SymbolicObj2(Shared2, Square, Circle, Polygon, Rotate2, Transform2), SymbolicObj3(Shared3, Cube, Sphere, Cylinder, Rotate3, Transform3, Extrude, ExtrudeM, RotateExtrude, ExtrudeOnEdgeOf), isScaleID, SharedObj(Empty, Full, Complement, UnionR, IntersectR, DifferenceR, Translate, Scale, Mirror, Outset, Shell, EmbedBoxedObj, WithRounding), quaternionToEuler)
+import Graphics.Implicit.Definitions(ℝ, SymbolicObj2(Shared2, Square, Circle, Polygon, Rotate2, Transform2), SymbolicObj3(Shared3, Cube, Sphere, Cylinder, BoxFrame, Rotate3, Transform3, Extrude, ExtrudeM, RotateExtrude, ExtrudeOnEdgeOf), isScaleID, SharedObj(Empty, Full, Complement, UnionR, IntersectR, DifferenceR, Translate, Scale, Mirror, Outset, Shell, EmbedBoxedObj, WithRounding), quaternionToEuler)
 import Graphics.Implicit.Export.TextBuilderUtils(Text, Builder, toLazyText, fromLazyText, bf)
 
 import Control.Monad.Reader (Reader, runReader, ask)
@@ -127,6 +127,10 @@ buildS3 (Cube (V3 w d h)) = call "cube" [bf w, bf d, bf h] []
 
 buildS3 (Sphere r) = callNaked "sphere" ["r = " <> bf r] []
 
+buildS3 (BoxFrame (V3 w d h) e) = callNaked "boxFrame"
+  ["w = " <> bf w, "d = " <> bf d, "h = " <> bf h, "e = " <> bf e]
+  []
+
 buildS3 (Cylinder h r1 r2) = callNaked "cylinder" [
                               "r1 = " <> bf r1
                              ,"r2 = " <> bf r2

Graphics/Implicit/ObjectUtil/GetBox3.hs

@@ -12,7 +12,7 @@ import Graphics.Implicit.Definitions
     ( Fastℕ,
       fromFastℕ,
       ExtrudeMScale(C2, C1),
-      SymbolicObj3(Shared3, Cube, Sphere, Cylinder, Rotate3, Transform3, Extrude, ExtrudeOnEdgeOf, ExtrudeM, RotateExtrude),
+      SymbolicObj3(Shared3, Cube, Sphere, Cylinder, Rotate3, Transform3, Extrude, ExtrudeOnEdgeOf, ExtrudeM, RotateExtrude, BoxFrame),
       Box3,
       ℝ,
       fromFastℕtoℝ,
@@ -34,6 +34,7 @@ getBox3 (Shared3 obj) = getBoxShared obj
 getBox3 (Cube size) = (pure 0, size)
 getBox3 (Sphere r) = (pure (-r), pure r)
 getBox3 (Cylinder h r1 r2) = (V3 (-r) (-r) 0, V3 r r h ) where r = max r1 r2
+getBox3 (BoxFrame b _) = (-b, b)
 -- (Rounded) CSG
 -- Simple transforms
 getBox3 (Rotate3 q symbObj) =

Graphics/Implicit/ObjectUtil/GetImplicit3.hs

@@ -6,10 +6,20 @@
 
 module Graphics.Implicit.ObjectUtil.GetImplicit3 (getImplicit3) where
 
-import Prelude (id, (||), (/=), either, round, fromInteger, Either(Left, Right), abs, (-), (/), (*), sqrt, (+), atan2, max, cos, minimum, ($), sin, pi, (.), Bool(True, False), ceiling, floor, pure, (==), otherwise)
+import Prelude (id, (||), (/=), either, round, fromInteger, Either(Left, Right), abs, (-), (/), (*), sqrt, (+), atan2, max, cos, minimum, ($), sin, pi, (.), Bool(True, False), ceiling, floor, pure, (==), otherwise, min)
 
 import Graphics.Implicit.Definitions
-    ( objectRounding, ObjectContext, ℕ, SymbolicObj3(Cube, Sphere, Cylinder, Rotate3, Transform3, Extrude, ExtrudeM, ExtrudeOnEdgeOf, RotateExtrude, Shared3), Obj3, ℝ2, ℝ, fromℕtoℝ, toScaleFn )
+    ( objectRounding,
+      ObjectContext,
+      ℕ,
+      SymbolicObj3(Cube, Sphere, Cylinder, Rotate3, Transform3, Extrude,
+                   ExtrudeM, ExtrudeOnEdgeOf, RotateExtrude, Shared3, BoxFrame),
+      Obj3,
+      ℝ2,
+      ℝ,
+      fromℕtoℝ,
+      toScaleFn,
+      ℝ3 )
 
 import Graphics.Implicit.MathUtil ( rmax, rmaximum )
 
@@ -37,6 +47,24 @@ getImplicit3 _ (Cylinder h r1 r2) = \(V3 x y z) ->
         θ = atan2 (r2-r1) h
     in
         max (d * cos θ) (abs (z-h/2) - (h/2))
+getImplicit3 _ (BoxFrame b e) = \p' ->
+    let p@(V3 px py pz) = abs p' - b
+        V3 qx qy qz = abs (p + pure e) - pure e
+        -- Splitting out bits from https://iquilezles.org/articles/distfunctions/
+        -- to make it somewhat readable.
+        length :: ℝ3 -> ℝ
+        length v = Linear.distance (abs v) $ pure 0
+        -- Component wise maximum. This is what the opengl language is doing, so we need
+        -- it for the function as defined by the blog above.
+        -- See "Maximum" http://15462.courses.cs.cmu.edu/fall2019/article/20
+        compMax :: ℝ3 -> ℝ3 -> ℝ3
+        compMax (V3 a1 b1 c1) (V3 a2 b2 c2) = V3 (max a1 a2) (max b1 b2) (max c1 c2)
+        -- These names don't mean anything, and are just for splitting up the code.
+        x', y', z' :: ℝ
+        x' = length (compMax (V3 px qy qz) (pure 0)) + min (max px (max qy qz)) 0
+        y' = length (compMax (V3 qx py qz) (pure 0)) + min (max qx (max py qz)) 0
+        z' = length (compMax (V3 qx qy pz) (pure 0)) + min (max qx (max qy pz)) 0
+    in min (min x' y') z'
 -- Simple transforms
 getImplicit3 ctx (Rotate3 q symbObj) =
     getImplicit3 ctx symbObj . Linear.rotate (Linear.conjugate q)

Graphics/Implicit/Primitives.hs

@@ -51,7 +51,7 @@ module Graphics.Implicit.Primitives (
                                      withRounding,
                                      _Shared,
                                      pattern Shared,
-                                     Object(Space, canonicalize)) where
+                                     Object(Space, canonicalize), boxFrame) where
 
 import Prelude(Applicative, Eq, Foldable, Num, abs, (<), otherwise, Num, (+), (-), (*), (/), (.), negate, Bool(True, False), Maybe(Just, Nothing), Either, fmap, ($), (**), sqrt, (<=), (&&), max, Ord)
 
@@ -84,6 +84,7 @@ import Graphics.Implicit.Definitions (ObjectContext, ℝ, ℝ2, ℝ3, Box2,
                                                    Cube,
                                                    Sphere,
                                                    Cylinder,
+                                                   BoxFrame,
                                                    Rotate3,
                                                    Transform3,
                                                    Extrude,
@@ -140,6 +141,9 @@ cylinder ::
     -> SymbolicObj3     -- ^ Resulting cylinder
 cylinder r = cylinder2 r r
 
+boxFrame :: ℝ3 -> ℝ -> SymbolicObj3
+boxFrame = BoxFrame
+
 cone ::
     ℝ                   -- ^ Radius of the cylinder
     -> ℝ                -- ^ Height of the cylinder

tests/GoldenSpec/Spec.hs

@@ -10,7 +10,7 @@ import Graphics.Implicit
 import Graphics.Implicit.Export.OutputFormat (OutputFormat (PNG))
 import Prelude
 import Test.Hspec ( describe, Spec )
-import Graphics.Implicit.Primitives (torus, ellipsoid, cone)
+import Graphics.Implicit.Primitives (torus, ellipsoid, cone, boxFrame)
 
 default (Int)
 
@@ -172,6 +172,12 @@ spec = describe "golden tests" $ do
       , ellipsoid 10 15 20
       , translate (V3 0 0 25) $ cone 20 20
       ]
+
+  golden "boxFrame" 2 $
+    union
+      [ boxFrame (V3 20 20 20) 2
+      , translate (V3 0 0 10) $ boxFrame (V3 10 10 10) 2
+      ]
 
   golden "closing-paths-1" 0.5 $
     extrudeM