create two new functions which deal in SymbolicObjs.

CHANGELOG.md

@@ -5,6 +5,7 @@
   * Added `polyhedron()` support [#497](https://github.com/Haskell-Things/ImplicitCAD/pull/497)
   * Added `import()` support [#505](https://github.com/Haskell-Things/ImplicitCAD/pull/505)
   * Improved syntax for module calling: now allows module calls in place of expressions []()
+  * Added `bbox()` and `render()` support for showing the bounding box of some geometry, and feeding said geometry from a variable or expression to the rendering engine. []()
 
 * Haskell interface changes
   * `extrude` arguments are now swapped, instead of `extrude obj height` we now have `extrude height obj` [#473](https://github.com/Haskell-Things/ImplicitCAD/issues/473)

Graphics/Implicit/ExtOpenScad/Default.hs

@@ -9,22 +9,27 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE FlexibleContexts #-}
 
+-- Allow us to use type signatures in patterns.
+{-# LANGUAGE ScopedTypeVariables #-}
+
 module Graphics.Implicit.ExtOpenScad.Default (defaultObjects) where
 
 -- be explicit about where we pull things in from.
 import Prelude (Bool(True, False), Maybe(Just, Nothing), ($), (<>), (<$>), fmap, pi, sin, cos, tan, asin, acos, atan, sinh, cosh, tanh, abs, signum, fromInteger, (.), floor, ceiling, round, exp, log, sqrt, max, min, atan2, (**), flip, (<), (>), (<=), (>=), (==), (/=), (&&), (||), not, show, foldl, (*), (/), mod, (+), zipWith, (-), otherwise, id, foldMap, fromIntegral, IO, pure, Int, isNaN, negate, RealFloat, Ord)
 import qualified Prelude as P (length)
 
-import Graphics.Implicit.Definitions (ℝ, ℕ)
+import Graphics.Implicit.Definitions (ℝ, ℕ, SymbolicObj2, SymbolicObj3)
 
-import Graphics.Implicit.ExtOpenScad.Definitions (VarLookup(VarLookup), OVal(OBool, OList, ONum, OString, OUndefined, OError, OFunc, OVargsModule, OIO), Symbol(Symbol), StateC, StatementI, SourcePosition, MessageType(TextOut, Warning), ScadOpts(ScadOpts))
+import Graphics.Implicit.ExtOpenScad.Definitions (ArgParser, (<|>), VarLookup(VarLookup), OVal(OBool, OList, ONum, OString, OUndefined, OError, OFunc, ONModule, OVargsModule, OIO), Symbol(Symbol), StateC, StatementI, SourcePosition, MessageType(TextOut, Warning), ScadOpts(ScadOpts))
 
 import Graphics.Implicit.ExtOpenScad.Util.OVal (toOObj, oTypeStr)
 
-import Graphics.Implicit.ExtOpenScad.Primitives (primitiveModules)
+import Graphics.Implicit.ExtOpenScad.Primitives (primitiveModules, argument)
 
 import Graphics.Implicit.ExtOpenScad.Util.StateC (scadOptions, modifyVarLookup, addMessage)
 
+import Graphics.Implicit.ObjectUtil (getBox2, getBox3)
+
 import Data.Int (Int64)
 
 import Data.Map (Map, fromList, insert)
@@ -54,6 +59,7 @@ defaultObjects withCSG = VarLookup $ fromList $
     <> defaultFunctionsSpecial
     <> defaultPolymorphicFunctions
     <> (if withCSG then primitiveModules else [])
+    <> objectFunctions
     <> varArgModules
 
 defaultConstants :: [(Symbol, OVal)]
@@ -119,6 +125,37 @@ defaultFunctionsSpecial =
         )
     ]
 
+-- | functions which operate on 3D geometry.
+objectFunctions :: [(Symbol, OVal)]
+objectFunctions = modVal <$>
+  [
+    ("bbox", bounding_box),
+    ("render", render)
+  ]
+  where
+    modVal (name,func) = (Symbol name, ONModule (Symbol name) func [[(Symbol "object", False)]])
+    -- Give us the bounding box around a portion of symbolic 3D geometry.
+    bounding_box :: SourcePosition -> ArgParser (StateC [OVal])
+    bounding_box _ = do
+      res <- do
+        object :: SymbolicObj3 <- argument "object"
+        pure $ toOObj $ getBox3 object
+        <|> do
+        object :: SymbolicObj2 <- argument "object"
+        pure $ toOObj $ getBox2 object
+      pure $ pure [res]
+    -- Pass the given object into the rendering pipeline.
+    render :: SourcePosition -> ArgParser (StateC [OVal])
+    render _ = do
+      res <- do
+        object :: SymbolicObj3 <- argument "object"
+        pure $ toOObj object
+        <|> do
+        object :: SymbolicObj2 <- argument "object"
+        pure $ toOObj object
+      pure $ pure [res]
+
+-- | Functions which can accept a variable number of arguments.
 varArgModules :: [(Symbol, OVal)]
 varArgModules =
     [

Graphics/Implicit/ExtOpenScad/Definitions.hs

@@ -34,7 +34,8 @@ module Graphics.Implicit.ExtOpenScad.Definitions (ArgParser(AP, APTest, APBranch
                                                   varUnion,
                                                   runImplicitCadM,
                                                   CanCompState,
-                                                  CanCompState'
+                                                  CanCompState',
+                                                  (<|>)
                                                   ) where
 
 import Prelude(Eq, Show, Ord, Maybe, Bool(True, False), IO, FilePath, (==), show, ($), (<>), and, zipWith, Int, (<$>))
@@ -308,3 +309,7 @@ data TestInvariant =
   | ContoursAreClosed
   | MeshIsWaterTight
     deriving (Show)
+
+-- | for composing ArgParsers.
+--(<|>) :: ArgParser a -> ArgParser a -> ArgParser a
+--(<|>) = mplus

Graphics/Implicit/ExtOpenScad/Eval/Module.hs

@@ -17,6 +17,7 @@ module Graphics.Implicit.ExtOpenScad.Eval.Module (
 import Prelude(Maybe(Just, Nothing), Bool(False), (.), ($), elem, error, filter, fmap, fst, init, last, length, not, notElem, null, show, snd, pure, zip, (<>), (&&), (==), (/=), String, (<$>))
 
 import Graphics.Implicit.ExtOpenScad.Definitions (
+                                                  Expr(),
                                                   OVal(OUModule, ONModule, ONModuleWithSuite, OVargsModule),
                                                   SourcePosition,
                                                   StateC,
@@ -36,8 +37,6 @@ import Data.Foldable (for_)
 
 import Data.Traversable (for)
 
-import Data.Text.Lazy as DTL (concat, intercalate)
-
 import Data.Text.Lazy (pack, Text)
 
 -- | Ensure that argsExpr fits into args.

Graphics/Implicit/ExtOpenScad/Primitives.hs

@@ -13,15 +13,15 @@
 {-# LANGUAGE OverloadedStrings #-}
 
 -- Export one set containing all of the primitive modules.
-module Graphics.Implicit.ExtOpenScad.Primitives (primitiveModules) where
+module Graphics.Implicit.ExtOpenScad.Primitives (primitiveModules, argument) where
 
 import Prelude(any, concat, elem, error, fromIntegral, foldr, head, length, mapM, (.), (+), Either(Left, Right), Bool(True, False), Maybe(Just, Nothing), ($), pure, show, either, id, (-), (==), (&&), (<), (*), cos, sin, pi, (/), (>), const, uncurry, (/=), (||), not, null, fmap, (<>), otherwise, (<*>), (<$>))
 
 import Graphics.Implicit.Definitions (ℝ, ℝ2, ℝ3, ℕ, SymbolicObj2, SymbolicObj3, ExtrudeMScale(C1), fromℕtoℝ, isScaleID)
 
 import Graphics.Implicit.Export.Util (centroid)
 
-import Graphics.Implicit.ExtOpenScad.Definitions (ArgParser, OVal (OObj2, OObj3, ONModule, ONModuleWithSuite), ScadOpts(importsAllowed), SourcePosition, StateC, Symbol(Symbol))
+import Graphics.Implicit.ExtOpenScad.Definitions (ArgParser, OVal (OObj2, OObj3, ONModule, ONModuleWithSuite), ScadOpts(importsAllowed), SourcePosition, StateC, Symbol(Symbol), (<|>))
 
 import Graphics.Implicit.ExtOpenScad.Util.ArgParser (contoursAreClosed, doc, defaultTo, example, meshIsWaterTight, test, eulerCharacteristic)
 
@@ -38,7 +38,7 @@ import Graphics.Implicit.TriUtil (Tri, Triangle)
 -- Note the use of a qualified import, so we don't have the functions in this file conflict with what we're importing.
 import qualified Graphics.Implicit.Primitives as Prim (withRounding, sphere, rect3, rect, translate, circle, polygon, polyhedron, extrude, cylinder2, union, unionR, intersect, intersectR, difference, differenceR, rotate, slice, transform, rotate3V, rotate3, transform3, scale, extrudeM, rotateExtrude, shell, mirror, pack3, pack2, torus, ellipsoid, cone)
 
-import Control.Monad (foldM, mplus)
+import Control.Monad (foldM)
 
 import Data.ByteString (readFile)
 
@@ -869,9 +869,6 @@ multmatrix = moduleWithSuite "multmatrix" $ \_ children -> do
 
 ---------------
 
-(<|>) :: ArgParser a -> ArgParser a -> ArgParser a
-(<|>) = mplus
-
 moduleWithSuite :: Text -> (SourcePosition -> [OVal] -> ArgParser (StateC [OVal])) -> (Symbol, SourcePosition -> [OVal] -> ArgParser (StateC [OVal]))
 moduleWithSuite name modArgMapper = (Symbol name, modArgMapper)