Added planeProj

1 files changed, 40 insertions, 4 deletions

diff --git a/Spear/Math/Matrix4.hs b/Spear/Math/Matrix4.hs
index ac2761f..a4ad651 100644
--- a/Spear/Math/Matrix4.hs
+++ b/Spear/Math/Matrix4.hs
@@ -35,7 +35,8 @@ module Spear.Math.Matrix4
 ,   reflectZ

     -- ** Projection

 ,   ortho

-,   perspective

+,   perspective
+,   planeProj

     -- * Operations

 ,   Spear.Math.Matrix4.zipWith

 ,   Spear.Math.Matrix4.map

@@ -44,7 +45,8 @@ module Spear.Math.Matrix4
 ,   inverse

 ,   mul

 ,   mulp

-,   muld

+,   muld
+,   mul'

 )

 where

 

@@ -420,8 +422,28 @@ perspective fovy r near far =
         0     f    0              0

         0     0    ((near+far)/a) (2*near*far/a)

         0     0    (-1)           0

+
+
+-- | Create a plane projection matrix.
+planeProj :: Vector3 -- ^ Plane normal
+          -> Float   -- ^ Plane distance from the origin
+          -> Vector3 -- ^ Projection direction
+          -> Matrix4
+planeProj n d l =
+    let c = n `V3.dot` l
+        nx = V3.x n
+        ny = V3.y n
+        nz = V3.z n
+        lx = V3.x l
+        ly = V3.y l
+        lz = V3.z l
+    in mat4
+        (d + c - nx*lx) (-ny*lx)          (-nz*lx)        (-lx*d)
+        (-nx*ly)        (d + c - ny*ly)   (-nz*ly)        (-ly*d)
+        (-nx*lz)        (-ny*lz)          (d + c - nz*lz) (-lz*d)
+        (-nx)           (-ny)             (-nz)           c
+

 

-    

 -- | Transpose the specified matrix.

 transpose :: Matrix4 -> Matrix4

 transpose m = mat4

@@ -609,7 +631,21 @@ mulp = mul 1
 

 -- | Transform the given directional vector in 3D space with the given matrix.

 muld :: Matrix4 -> Vector3 -> Vector3

-muld = mul 0

+muld = mul 0
+
+
+-- | Transform the given vector with the given matrix.
+--
+-- The vector is brought from homogeneous space to 3D space by performing a
+-- perspective divide.
+mul' :: Float -> Matrix4 -> Vector3 -> Vector3
+mul' w m v = vec3 (x'/w') (y'/w') (z'/w')

+    where

+        v' = vec4 (V3.x v) (V3.y v) (V3.z v) w

+        x' = row0 m `V4.dot` v'

+        y' = row1 m `V4.dot` v'

+        z' = row2 m `V4.dot` v'
+        w' = row3 m `V4.dot` v'

 

 

 toRAD = (*pi) . (/180)