1 files changed, 36 insertions, 3 deletions

diff --git a/Spear/Math/MatrixUtils.hs b/Spear/Math/MatrixUtils.hs
index e6e498f..434e36a 100644
--- a/Spear/Math/MatrixUtils.hs
+++ b/Spear/Math/MatrixUtils.hs
@@ -1,6 +1,10 @@
 module Spear.Math.MatrixUtils
 (
     fastNormalMatrix
+,   rpgTransform
+,   pltTransform
+,   rpgInverse
+,   pltInverse
 )
 where
 
@@ -21,6 +25,35 @@ fastNormalMatrix m =
         (M4.m02 m') (M4.m12 m') (M4.m22 m')
 
 
+-- | Maps the given 2D transformation matrix to a 3D transformation matrix.
+rpgTransform :: Float -- ^ The height above the ground.
+             -> Matrix3 -> Matrix4
+rpgTransform h mat =
+    let r = let r' = M3.right mat in vec3 (V2.x r') (V2.y r') 0
+        u = V3.unity
+        f = let f' = M3.forward mat in vec3 (V2.x f') 0 (-V2.y f')
+        t = (vec3 0 h 0) + let t' = M3.position mat in -(vec3 (V2.x t') 0 (-V2.y t'))
+    in mat4
+        (V3.x r) (V3.x u) (V3.x f) (V3.x t)
+        (V3.y r) (V3.y u) (V3.y f) (V3.y t)
+        (V3.z r) (V3.z u) (V3.z f) (V3.z t)
+        0        0        0        1
+
+
+-- | Maps the given 2D transformation matrix to a 3D transformation matrix.
+pltTransform :: Matrix3 -> Matrix4
+pltTransform mat =
+    let r = let r' = M3.right mat in vec3 (V2.x r') (V2.y r') 0
+        u = let u' = M3.up mat in vec3 (V2.x u') (V2.y u') 0
+        f = V3.unitz
+        t = let t' = M3.position mat in vec3 (V2.x t') (V2.y t') 0
+    in mat4
+        (V3.x r) (V3.x u) (V3.x f) (V3.x t)
+        (V3.y r) (V3.y u) (V3.y f) (V3.y t)
+        (V3.z r) (V3.z u) (V3.z f) (V3.z t)
+        0        0        0        1
+
+
 -- | Compute the inverse transform of the given transformation matrix.
 --
 -- This function maps an object's transform in 2D to the object's inverse in 3D.
@@ -34,12 +67,12 @@ rpgInverse h mat =
     let r = let r' = M3.right mat in vec3 (V2.x r') (V2.y r') 0
         u = V3.unity
         f = let f' = M3.forward mat in vec3 (V2.x f') 0 (-V2.y f')
-        t = let t' = M3.position mat in -(vec3 (V2.x t') 0 (-V2.y t'))
+        t = (vec3 0 h 0) + let t' = M3.position mat in -(vec3 (V2.x t') 0 (-V2.y t'))
     in mat4
         (V3.x r) (V3.y r) (V3.z r) (t `V3.dot` r)
         (V3.x u) (V3.y u) (V3.z u) (t `V3.dot` u)
         (V3.x f) (V3.y f) (V3.z f) (t `V3.dot` f)
-        0     0     0     1
+        0        0        0        1
 
 
 -- | Compute the inverse transform of the given transformation matrix.
@@ -59,4 +92,4 @@ pltInverse mat =
         (V3.x r) (V3.y r) (V3.z r) (t `V3.dot` r)
         (V3.x u) (V3.y u) (V3.z u) (t `V3.dot` u)
         (V3.x f) (V3.y f) (V3.z f) (t `V3.dot` f)
-        0     0     0     1
+        0        0        0        1