From 376375008c8044ba6e5cbc25906cf5f5f8a068dc Mon Sep 17 00:00:00 2001
From: Stefan Dresselhaus <sdressel@techfak.uni-bielefeld.de>
Date: Wed, 7 May 2014 09:51:35 +0200
Subject: [PATCH] tessellation-factor is now adaptive

- tessellation gets reduced in distance
- tess-factor is now adaptive
---
 shaders/map/tessControl.shader | 31 ++++++++++++++++++++++++++-----
 src/Main.hs                    | 12 +++++++-----
 src/Types.hs                   |  1 +
 3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/shaders/map/tessControl.shader b/shaders/map/tessControl.shader
index e7a5d25..a6f81b1 100644
--- a/shaders/map/tessControl.shader
+++ b/shaders/map/tessControl.shader
@@ -10,6 +10,9 @@ out vec4 tcColor[];
 out vec3 tcNormal[];
 uniform float TessLevelInner = 1.0; // controlled by keyboard buttons
 uniform float TessLevelOuter = 1.0; // controlled by keyboard buttons
+uniform mat4 ProjectionMatrix;
+uniform mat4 ViewMatrix;
+uniform mat3 NormalMatrix;
 
 #define ID gl_InvocationID
 
@@ -18,10 +21,28 @@ void main()
     tcPosition[ID] = vPosition[ID];
     tcColor[ID] = vColor[ID];
     tcNormal[ID] = vNormal[ID];
+    float dist = (ProjectionMatrix * ViewMatrix * vec4(vPosition[ID], 1)).z;
     if (ID == 0) {
-        gl_TessLevelInner[0] = TessLevelInner;
-        gl_TessLevelOuter[0] = TessLevelOuter;
-        gl_TessLevelOuter[1] = TessLevelOuter;
-        gl_TessLevelOuter[2] = TessLevelOuter;
+	if (dist < 30) {
+	        gl_TessLevelInner[0] = TessLevelInner;
+        	gl_TessLevelOuter[0] = TessLevelOuter;
+	        gl_TessLevelOuter[1] = TessLevelOuter;
+        	gl_TessLevelOuter[2] = TessLevelOuter;
+	} else if (dist < 50) {
+	        gl_TessLevelInner[0] = max(TessLevelInner-1.0,1.0);
+        	gl_TessLevelOuter[0] = max(TessLevelOuter-1.0,1.0);
+	        gl_TessLevelOuter[1] = max(TessLevelOuter-1.0,1.0);
+        	gl_TessLevelOuter[2] = max(TessLevelOuter-1.0,1.0);
+	} else if (dist < 100) {
+	        gl_TessLevelInner[0] = max(TessLevelInner-2.0,1.0);
+        	gl_TessLevelOuter[0] = max(TessLevelOuter-2.0,1.0);
+	        gl_TessLevelOuter[1] = max(TessLevelOuter-2.0,1.0);
+        	gl_TessLevelOuter[2] = max(TessLevelOuter-2.0,1.0);
+	} else {
+	        gl_TessLevelInner[0] = 1.0;
+        	gl_TessLevelOuter[0] = 1.0;
+	        gl_TessLevelOuter[1] = 1.0;
+        	gl_TessLevelOuter[2] = 1.0;
+	}
     }
-}
\ No newline at end of file
+}
diff --git a/src/Main.hs b/src/Main.hs
index 209ae84..f033a77 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -132,6 +132,7 @@ main =
                         }
               , _io                  = IOState
                         { _clock               = now
+                        , _tessClockFactor     = 0
                         }
               , _mouse               = MouseState
                         { _isDown              = False
@@ -234,23 +235,24 @@ run = do
 		targetFrametime = 1.0/targetFramerate
 		targetFrametimeμs = targetFrametime * 1000000.0
         now <- getCurrentTime
-        diff <- return $ diffUTCTime now (state ^. io.clock) -- get time-diffs
-        title <- return $ unwords ["Pioneers @ ",show ((round . double $ 1.0/diff)::Int),"fps"]
+        let diff  = diffUTCTime now (state ^. io.clock) -- get time-diffs
+            title = unwords ["Pioneers @ ",show ((round . double $ 1.0/diff)::Int),"fps"]
         setWindowTitle (env ^. windowObject) title
         let 	sleepAmount = floor ((targetFrametime - double diff)*1000000) :: Int -- get time until next frame in microseconds
+                clockFactor = (state ^. io.tessClockFactor)
 		tessChange
-			| (sleepAmount > (floor $0.1*targetFrametimeμs)) && (state ^. gl.glMap.stateTessellationFactor < 5) = ((+)1 :: Int -> Int) 
+			| (clockFactor > (2*targetFrametimeμs)) && (state ^. gl.glMap.stateTessellationFactor < 5) = ((+)1 :: Int -> Int) 
 									-- > factor < 5 & 10% of frame idle -> increase graphics
 			| sleepAmount < 0 && (state ^. gl.glMap.stateTessellationFactor > 1) = (flip (-) 1 :: Int -> Int)
 									-- frame used up completely -> decrease
 			| otherwise = ((+)0 :: Int -> Int)              -- 0ms > x > 10% -> keep settings
         when (sleepAmount > 0) $ threadDelay sleepAmount
-	print targetFrametimeμs
         return (now,tessChange,sleepAmount)
     -- set state with new clock-time
     modify $ (io.clock .~ mt)
            . (gl.glMap.stateTessellationFactor %~ tc)
-    liftIO $ putStrLn $ concat $ ["TessFactor at: ",show (state ^. gl.glMap.stateTessellationFactor), " - slept for ",show sleepAmount, "μs."]
+           . (io.tessClockFactor %~ (((+) (fromIntegral sleepAmount)).((*) 0.99)))
+    -- liftIO $ putStrLn $ concat $ ["TessFactor at: ",show (state ^. gl.glMap.stateTessellationFactor), " - slept for ",show sleepAmount, "μs."]
     shouldClose' <- return $ state ^. window.shouldClose
     unless shouldClose' run
 
diff --git a/src/Types.hs b/src/Types.hs
index 8f6aae6..af45b18 100644
--- a/src/Types.hs
+++ b/src/Types.hs
@@ -51,6 +51,7 @@ data CameraState = CameraState
 
 data IOState = IOState
     { _clock               :: !UTCTime
+    , _tessClockFactor     :: !Double
     }
 
 data GameState = GameState