Temporary: put guards into getImplicit*

Related to #441

This will get factored out into canonicalization pass

Graphics/Implicit/ObjectUtil/GetImplicit2.hs

@@ -11,7 +11,7 @@ module Graphics.Implicit.ObjectUtil.GetImplicit2 (getImplicit2) where
 import Prelude(cycle, (/=), uncurry, fst, Eq, zip, drop, abs, (-), (/), sqrt, (*), (+), length, fmap, (<=), (&&), (>=), (||), odd, ($), (>), filter, (<), minimum, (.), sin, cos)
 
 import Graphics.Implicit.Definitions
-    ( objectRounding, ObjectContext, SymbolicObj2(Square, Circle, Polygon, Rotate2, Transform2, Shared2), SharedObj (Empty), Obj2, ℝ2, ℝ )
+    ( objectRounding, ObjectContext, SymbolicObj2(Square, Circle, Polygon, Rotate2, Transform2, Shared2), SharedObj (Empty), Obj2, ℝ2, ℝ, hasZeroComponent )
 
 import Graphics.Implicit.MathUtil
     ( distFromLineSeg, rmaximum )
@@ -35,10 +35,15 @@ scanUniqueCircular
 circularPairs :: [a] -> [(a,a)]
 circularPairs as = zip as $ drop 1 $ cycle as
 
+getEmptySpace :: ObjectContext -> V2 ℝ -> ℝ
+getEmptySpace c = getImplicitShared c (Empty :: SharedObj SymbolicObj2 V2 ℝ)
+
 getImplicit2 :: ObjectContext -> SymbolicObj2 -> Obj2
 -- Primitives
+getImplicit2 ctx (Square vec) | hasZeroComponent vec = getEmptySpace ctx
 getImplicit2 ctx (Square (V2 dx dy)) =
     \(V2 x y) -> rmaximum (objectRounding ctx) [abs (x-dx/2) - dx/2, abs (y-dy/2) - dy/2]
+getImplicit2 c (Circle 0) = getEmptySpace c
 getImplicit2 _ (Circle r) =
     \(V2 x y) -> sqrt (x * x + y * y) - r
 -- FIXME: stop ignoring rounding for polygons.
@@ -65,6 +70,14 @@ getImplicit2 ctx (Rotate2 θ symbObj) =
         obj = getImplicit2 ctx symbObj
     in
         obj $ V2 (x*cos θ + y*sin θ) (y*cos θ - x*sin θ)
+-- ignore if zeroes, TODO(srk): produce warning
+-- TODO(srk): produce warning and ignore if we get a non-invertible matrix
+getImplicit2 ctx (Transform2
+                   (V3 (V3 x _ _)
+                       (V3 _ y _)
+                       (V3 _ _ _)
+                   )
+                   symbObj) | hasZeroComponent (V2 x y) = getImplicit2 ctx symbObj
 getImplicit2 ctx (Transform2 m symbObj) =
     \vin ->
     let

Graphics/Implicit/ObjectUtil/GetImplicit3.hs

@@ -9,7 +9,7 @@ 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 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), Obj3, ℝ2, ℝ, fromℕtoℝ, toScaleFn, SharedObj(Empty), hasZeroComponent )
 
 import Graphics.Implicit.MathUtil ( rmax, rmaximum )
 
@@ -17,20 +17,26 @@ import qualified Data.Either as Either (either)
 
 -- Use getImplicit for handling extrusion of 2D shapes to 3D.
 import Graphics.Implicit.ObjectUtil.GetImplicitShared (getImplicitShared)
-import Linear (V2(V2), V3(V3))
+import Linear (V2(V2), V3(V3), V4(V4))
 import qualified Linear
 
 import {-# SOURCE #-} Graphics.Implicit.Primitives (getImplicit)
 
 default (ℝ)
 
+getEmptySpace :: ObjectContext -> V3 ℝ -> ℝ
+getEmptySpace c = getImplicitShared c (Empty :: SharedObj SymbolicObj3 V3 ℝ)
+
 -- Get a function that describes the surface of the object.
 getImplicit3 :: ObjectContext -> SymbolicObj3 -> Obj3
 -- Primitives
+getImplicit3 ctx (Cube vec) | hasZeroComponent vec = getEmptySpace ctx
 getImplicit3 ctx (Cube (V3 dx dy dz)) =
     \(V3 x y z) -> rmaximum (objectRounding ctx) [abs (x-dx/2) - dx/2, abs (y-dy/2) - dy/2, abs (z-dz/2) - dz/2]
+getImplicit3 c (Sphere 0) = getEmptySpace c
 getImplicit3 _ (Sphere r) =
     \(V3 x y z) -> sqrt (x*x + y*y + z*z) - r
+getImplicit3 c (Cylinder 0 _ _) = getEmptySpace c
 getImplicit3 _ (Cylinder h r1 r2) = \(V3 x y z) ->
     let
         d = sqrt (x*x + y*y) - ((r2-r1)/h*z+r1)
@@ -40,6 +46,15 @@ getImplicit3 _ (Cylinder h r1 r2) = \(V3 x y z) ->
 -- Simple transforms
 getImplicit3 ctx (Rotate3 q symbObj) =
     getImplicit3 ctx symbObj . Linear.rotate (Linear.conjugate q)
+-- ignore if zeroes, TODO(srk): produce warning
+-- TODO(srk): produce warning and ignore if we get a non-invertible matrix
+getImplicit3 ctx (Transform3
+                   (V4 (V4 x _ _ _)
+                       (V4 _ y _ _)
+                       (V4 _ _ z _)
+                       (V4 _ _ _ _)
+                   )
+                   symbObj) | hasZeroComponent (V3 x y z) = getImplicit3 ctx symbObj
 getImplicit3 ctx (Transform3 m symbObj) =
     getImplicit3 ctx symbObj . Linear.normalizePoint . ((Linear.inv44 m) Linear.!*) . Linear.point
 -- 2D Based

Graphics/Implicit/ObjectUtil/GetImplicitShared.hs

@@ -15,7 +15,7 @@ import {-# SOURCE #-} Graphics.Implicit.Primitives (Object(getImplicit'))
 import Prelude (flip, (-), (*), (>), (<), (&&), (/), product, abs, (**), fmap, (.), negate, ($), const)
 
 import Graphics.Implicit.Definitions
-    ( objectRounding, ObjectContext, SharedObj(Empty, Full, Complement, UnionR, IntersectR, DifferenceR, Translate, Scale, Mirror, Shell, Outset, EmbedBoxedObj, WithRounding), ComponentWiseMultable((⋯/)), ℝ, minℝ )
+    ( objectRounding, ObjectContext, SharedObj(Empty, Full, Complement, UnionR, IntersectR, DifferenceR, Translate, Scale, Mirror, Shell, Outset, EmbedBoxedObj, WithRounding), ComponentWiseMultable((⋯/)), ℝ, minℝ, hasZeroComponent, hasNaNComponent )
 
 import Graphics.Implicit.MathUtil (infty, rmax, rmaximum, rminimum, reflect)
 
@@ -75,6 +75,10 @@ getImplicitShared ctx (DifferenceR r symbObj symbObjs) =
 -- Simple transforms
 getImplicitShared ctx (Translate v symbObj) = \p ->
   getImplicit' ctx symbObj (p - v)
+-- ignore if zeroes, TODO(srk): produce warning
+getImplicitShared ctx (Scale s symbObj) | hasZeroComponent s = getImplicit' ctx symbObj
+-- ignore if NaNs, TODO(srk): produce warning
+getImplicitShared ctx (Scale s symbObj) | hasNaNComponent s = getImplicit' ctx symbObj
 getImplicitShared ctx (Scale s symbObj) = \p ->
   normalize s * getImplicit' ctx symbObj (p ⋯/ s)
 getImplicitShared ctx (Mirror v symbObj) =

Graphics/Implicit/Primitives.hs

@@ -130,8 +130,6 @@ cylinder2 ::
     -> ℝ                -- ^ Second radius of the cylinder
     -> ℝ                -- ^ Height of the cylinder
     -> SymbolicObj3     -- ^ Resulting cylinder
-
-cylinder2 _ _ 0 = emptySpace  -- necessary to prevent a NaN
 cylinder2 r1 r2 h
   | h < 0 = mirror (V3 0 0 1) $ cylinder2 r1 r2 (abs h)
   | otherwise = Cylinder h r1 r2