Add axis-aligned plane.

1 files changed, 47 insertions, 13 deletions

diff --git a/Spear/Math/Plane.hs b/Spear/Math/Plane.hs
index 5440a43..cbf5aed 100644
--- a/Spear/Math/Plane.hs
+++ b/Spear/Math/Plane.hs
@@ -2,41 +2,75 @@
 

 module Spear.Math.Plane

 (

-    Plane

-,   plane

-,   classify

+  Plane(..)

+, AxisPlane(..)

+, plane

+, axisPlane

+, planeClassify

+, axisPlaneClassify

 )

 where

 

 import           Spear.Math.Vector

 import           Spear.Prelude

 

+

+data Axis = X | Y | Z deriving (Eq, Show)

+

+data AxisOrientation = PositiveAxis | NegativeAxis deriving (Eq, Show)

+

 data PointPlanePos = Front | Back | Contained deriving (Eq, Show)

 

+-- | A 3D plane.

 data Plane = Plane

-    { n :: {-# UNPACK #-} !Vector3,

-      d :: {-# UNPACK #-} !Float

+    { planeNormal   :: {-# UNPACK #-} !Vector3

+    , planeDistance :: {-# UNPACK #-} !Float

     }

     deriving(Eq, Show)

 

+-- | An axis-aligned 3D plane.

+data AxisPlane = AxisPlane

+    { axisPlaneAxis     :: !Axis

+    , axisPlaneDistance :: {-# UNPACK #-} !Float

+    , axisPlaneNormal   :: !AxisOrientation

+    }

+    deriving (Eq, Show)

+

+

 -- | Construct a plane from  a normal vector and a distance from the origin.

 plane :: Vector3 -> Float -> Plane

 plane n d = Plane (normalise n) d

 

+-- | Construct an axis-aligned plane.

+axisPlane :: Axis -> Float -> AxisOrientation -> AxisPlane

+axisPlane = AxisPlane

+

 -- | Construct a plane from three points.

 --

 -- Points must be given in counter-clockwise order.

-fromPoints :: Vector3 -> Vector3 -> Vector3 -> Plane

-fromPoints p0 p1 p2 = Plane n d

-           where n  = normalise $ v1 `cross` v2

-                 v1 = p2 - p1

-                 v2 = p0 - p1

-                 d  = p0 `dot` n

+planeFromPoints :: Vector3 -> Vector3 -> Vector3 -> Plane

+planeFromPoints p0 p1 p2 = Plane n d

+    where n  = normalise $ v1 `cross` v2

+          v1 = p2 - p1

+          v2 = p0 - p1

+          d  = p0 `dot` n

 

 -- | Classify the given point's relative position with respect to the plane.

-classify :: Plane -> Vector3 -> PointPlanePos

-classify (Plane n d) pt =

+planeClassify :: Plane -> Vector3 -> PointPlanePos

+planeClassify (Plane n d) pt =

     case (n `dot` pt - d) `compare` 0 of

         GT -> Front

         LT -> Back

         EQ -> Contained

+

+-- | Classify the given point's relative position with respect to the plane.

+axisPlaneClassify :: AxisPlane -> Vector3 -> PointPlanePos

+axisPlaneClassify (AxisPlane axis d _) (Vector3 x y z) =

+    let classify coord

+          | coord < d = Back

+          | coord > d = Front

+          | otherwise = Contained

+    in case axis of

+        X -> classify x

+        Y -> classify y

+        Z -> classify z