From 2628b42a54ae36ac4706114ed7a0abb6d52eefd5 Mon Sep 17 00:00:00 2001
From: Kiana Sheibani <kiana.a.sheibani@gmail.com>
Date: Thu, 1 Dec 2022 08:43:57 -0500
Subject: [PATCH] Fix rendering bugs

---
 src/Render/Camera.idr | 6 ++++--
 src/Render/Scene.idr  | 3 +--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/Render/Camera.idr b/src/Render/Camera.idr
index 197138f..c1627d7 100644
--- a/src/Render/Camera.idr
+++ b/src/Render/Camera.idr
@@ -24,5 +24,7 @@ PictureType cam = Array [cam.pixh, cam.pixw, 3] Double
 export
 pointToPix : Camera -> Point 2 Double -> Point 2 Integer
 pointToPix (MkCamera mat sw sh pw ph) p =
-  let p' = applyInv mat p
-  in  point [cast (p'.x / sw * cast pw), cast (p'.y / sh * cast ph)]
+  let pw' = cast pw
+      ph' = cast ph
+      p' = applyInv mat p
+  in  point [cast (p'.x / sw * pw' + pw' / 2), cast (p'.y / sh * ph' + ph' / 2)]
diff --git a/src/Render/Scene.idr b/src/Render/Scene.idr
index b9e3b81..cd9a9d1 100644
--- a/src/Render/Scene.idr
+++ b/src/Render/Scene.idr
@@ -28,7 +28,7 @@ render cam sc = joinAxes $ foldl drawObject (repeat _ sc.bgcolor) sc.objects
     drawPixel (x, y, col) arr = fromMaybe arr $ do
       x' <- integerToFin x _
       y' <- integerToFin y _
-      pure $ indexUpdate [x',y'] (over col) arr
+      pure $ indexUpdate [y',x'] (over col) arr
 
     drawObject : Array [cam.pixh, cam.pixw] Color -> Object -> Array [cam.pixh, cam.pixw] Color
     drawObject pic (MkObject obj) =
@@ -50,7 +50,6 @@ renderToPPM dest cam sc = do
         setByte buf i (cast $ x * 255)
         modifyIORef ind (+1)
 
-
   _ <- if !(exists dest) then removeFile {io} dest else pure $ Right ()
   Right h <- openFile dest Append
     | Left err => pure $ Left err