From 72b93bbaaa0219f1161448b3e6136b795b0f2041 Mon Sep 17 00:00:00 2001
From: Marc Sunet <jeannekamikaze@gmail.com>
Date: Sun, 2 Sep 2012 11:14:40 +0200
Subject: Added toClip

---
 Spear.lkshw               |  4 ++--
 Spear/Math/MatrixUtils.hs | 13 +++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Spear.lkshw b/Spear.lkshw
index 6587fba..8c102af 100644
--- a/Spear.lkshw
+++ b/Spear.lkshw
@@ -1,10 +1,10 @@
 Version of workspace file format:
                1
 Time of storage:
-               "Sun Sep  2 11:06:10 CEST 2012"
+               "Sun Sep  2 11:14:26 CEST 2012"
 Name of the workspace:
                "Spear"
 File paths of contained packages:
                ["demos/simple-scene/simple-scene.cabal","Spear.cabal"]
 Maybe file path of an active package:
-               Just "Spear.cabal"
\ No newline at end of file
+               Just "demos/simple-scene/simple-scene.cabal"
\ No newline at end of file
diff --git a/Spear/Math/MatrixUtils.hs b/Spear/Math/MatrixUtils.hs
index dcc1965..7502234 100644
--- a/Spear/Math/MatrixUtils.hs
+++ b/Spear/Math/MatrixUtils.hs
@@ -5,10 +5,12 @@ module Spear.Math.MatrixUtils
 ,   pltTransform
 ,   rpgInverse
 ,   pltInverse
+,   toClip
 )
 where
 
 
+import Spear.Math.Camera as Cam
 import Spear.Math.Matrix3 as M3
 import Spear.Math.Matrix4 as M4
 import Spear.Math.Vector2 as V2
@@ -88,3 +90,14 @@ rpgInverse h a rot = M4.inverseTransform . rpgTransform h a rot
 -- Use this in games like platformers and space invaders style games.
 pltInverse :: Matrix3 -> Matrix4
 pltInverse = M4.inverseTransform . pltTransform
+
+
+-- | Transform an object from object to clip space coordinates.
+toClip :: Camera -> Matrix4 -> Vector3 -> Vector2
+toClip cam model p =
+    let
+        view = M4.inverseTransform $ Cam.transform cam
+        proj = Cam.projection cam
+        p' = (proj * view * model) `M4.mulp` p
+    in
+        vec2 (V3.x p') (V3.y p')
-- 
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