Unify shadow stencil tests, inverts shadow when light source occluded

src/Render.hs

@@ -62,8 +62,9 @@ createLightMap pdata lightPoints nWalls nSils nsurfVs = do
         -- stencil out shadows
         colorMask $= Color4 Disabled Disabled Disabled Disabled
         clear [StencilBuffer]
-        cullFace $= Just Back
-        stencilOp $= (OpKeep,OpKeep,OpIncr)
+        cullFace $= Nothing
+        stencilOpSeparate Front $= (OpKeep,OpKeep,OpIncrWrap)
+        stencilOpSeparate Back  $= (OpKeep,OpKeep,OpDecrWrap)
         stencilFunc $= (Always, 0, 255)
         currentProgram $= Just (_shaderProgram $ _lightingOccludeShader pdata)
         uniform (head $  _shaderCustomUnis $ _lightingOccludeShader pdata)
@@ -78,21 +79,11 @@ createLightMap pdata lightPoints nWalls nSils nsurfVs = do
         drawShader (_lightingLineShadowShader pdata) nSils
         depthClamp $= Disabled
 
-        cullFace $= Just Front
-        stencilOp $= (OpKeep,OpKeep,OpDecr)
-        currentProgram $= Just (_shaderProgram $ _lightingOccludeShader pdata)
-        drawShader (_lightingOccludeShader pdata) nWalls
-
-        --stencilOp $= (OpKeep,OpIncr,OpKeep)
-        currentProgram $= Just (_shaderProgram $ _lightingLineShadowShader pdata)
-        depthClamp $= Enabled
-        drawShader (_lightingLineShadowShader pdata) nSils
-        depthClamp $= Disabled
-
         -- draw geometry surfaces
         cullFace $= Just Back
         --colorMask $= Color4 Disabled Disabled Disabled Enabled
         colorMask $= Color4 Enabled Enabled Enabled Enabled
+        stencilOp $= (OpKeep,OpKeep,OpKeep)
         stencilFunc $= (Equal, 0, 255)
         currentProgram $= Just (_shaderProgram $ _lightingSurfaceShader pdata)
         uniform (head $  _shaderCustomUnis $ _lightingSurfaceShader pdata)