Use stencil to black out floor shadows

src/Picture/Preload.hs

@@ -23,6 +23,7 @@ import qualified Control.Foldl as F
 data RenderData = RenderData
     { _lightSourceShader :: FullShader (Float,Float,Float,Float)
     , _wallShadowShader  :: FullShader (Point2,Point2,Point2,Point2)
+    , _wallLightShader  :: FullShader (Point3)
     , _backgroundShader  :: FullShader (Point2,Point2,Point2,Point2)
     , _fullscreenShader  :: FullShader ()
     , _wallShader :: FullShader (Point3,Point4)
@@ -47,6 +48,9 @@ preloadRender = do
     wsShad <- makeShaderCustomUnis "wallShadow" [vert,geom,frag] [(0,4),(1,4)] Points pokeWPStrat
                 ["lightPos"]
 
+    wlLightShad <- makeShaderCustomUnis "wallLight" [vert,frag] [(0,3)] TriangleStrip pokeLightWallStrat
+                    ["lightPosRadLum"]
+
     wlShad <- makeShader "wall" [vert,frag] [(0,3),(1,4)] TriangleStrip pokeWlStrat
 
     bslist <- makeShader "basic"   [vert,frag]      [(0,3),(1,4)]       Triangles pokeTriStrat
@@ -91,6 +95,7 @@ preloadRender = do
         , _dummyPtr = dummyptr
         , _lightSourceShader = lsShad
         , _wallShadowShader  = wsShad
+        , _wallLightShader   = wlLightShad
         , _wallShader        = wlShad
         , _backgroundShader  = bgShad
         , _fullscreenShader  = fsShad
@@ -116,7 +121,6 @@ setupFramebuffer = do
     fboRBO <- genObjectName
     bindRenderbuffer Renderbuffer $= fboRBO
     renderbufferStorage Renderbuffer Depth24Stencil8 (RenderbufferSize 800 600)
-                                    -- not sure if the stencil is needed
     framebufferRenderbuffer Framebuffer DepthStencilAttachment Renderbuffer fboRBO
 
     fboStatus <- framebufferStatus Framebuffer
@@ -170,6 +174,9 @@ frag = FragmentShader
 pokeWPStrat :: (Point2,Point2,Point2,Point2) -> [[[Float]]]
 pokeWPStrat ((x,y),(z,w),(a,b),(c,d)) = [[[x,y,z,w],[a,b,c,d]]]
 
+pokeLightWallStrat :: Point3 -> [[[Float]]]
+pokeLightWallStrat (x,y,z) = [[[x,y,z]]]
+
 pokeBGStrat :: a -> [[[Float]]]
 pokeBGStrat = const []