change raster method, add todo to readme

README.md

@@ -5,7 +5,7 @@ make sure you have nix installed
 curl https://nixos.org/nix/install | sh
 ```
 
-to build:
+### to build:
 ```
 nix-build
 
@@ -15,7 +15,7 @@ run with
 ./result/bin/image-triangles -o output.svg
 ```
 
-to develop on:
+### to develop on:
 ```
 cabal --enable-nix build
 ```
@@ -29,3 +29,15 @@ run with
 ```
 ./dist/build/image-triangles/image-triangles -o output.svg
 ```
+
+### todo
+    - Why is the area wrong for the top right corner?
+    - Rasterization for triangles
+    - Cmdline interface that lets you set number of triangles, and smallness
+    - Pointy triangle filter
+    - Confirm diagrams is rendering triangles in the correct places.
+    - Cache transformations to the colors library
+    - Hip has a map transformation. It also depends on the colours library, does it use it?
+    - Check that hip colors are srgb
+    - Think about opacity. What if everything was completely opaque? What should we do with areas that aren’t 100% covered at the end?
+  

image-triangles.cabal

@@ -64,4 +64,4 @@ executable image-triangles
 
   -- Base language which the package is written in.
   default-language:    Haskell2010
-  ghc-options: -threaded -O3 
+  ghc-options: -threaded

src/Main.hs

@@ -26,5 +26,7 @@ main = do
     gen <- getStdGen
     print gen
     let dims = (cols image, rows image)
-    let triangleList = sortOn (Tri.area) . withStrategy (parListChunk 50 rseq) . take 600 . map (Tri.getRandomTriangle image) . genList $ gen
-    mainWith . mconcat . map (renderTri image) $ triangleList
+    let triangleList = take 200 . sortOn (negate . Tri.area) . take 500 . map (Tri.getRandomTriangle image) . genList $ gen
+    -- print $ map Tri.area $ take 20 $ triangleList
+    -- print $ Tri.area . last $ triangleList
+    mainWith . mconcat . withStrategy (parListChunk 50 rseq) . map (renderTri image) $ triangleList

src/Render.hs

@@ -14,7 +14,7 @@ makeTriangle verts col = fromVertices verts
                        # strokeLocLoop 
                        # fc col
                        # lw 0
-                       # opacity 0.2
+                       # opacity 0.8
 
 
 -- tupleFromIntegral :: (Int, Int) -> (Int, Int) -> (Double, Double)

src/Triangles.hs

@@ -9,7 +9,7 @@
 
 module Triangles where
 
-import Graphics.Image hiding (map)
+import Graphics.Image hiding (map, zipWith, sum, minimum, maximum)
 import System.Random
 import qualified Data.Colour.SRGB as C
 import qualified Data.Colour as C
@@ -21,8 +21,18 @@ type Pixel_ = Pixel RGB Double
 type Point = (Int, Int)
 type Triangle = (Point, Point, Point)
 
+shoelace :: [Point] -> Double 
+shoelace pts = halve . sum $ zipWith (*) (zipWith (+) xs' xs) (zipWith (-) ys' ys)
+    where
+        xs = map snd pts
+        ys = map fst pts
+        ys' = tail . cycle $ xs
+        xs' = tail . cycle $ ys
+        halve b =  (fromIntegral b) / 2.0
+
 area :: Triangle -> Double
-area (p1, p2, p3) = ccArea . swapForCounterClockwise . sortOn fst $ [p1, p2, p3]
+area (p1, p2, p3) = abs . shoelace $ [p1, p2, p3]
+-- area (p1, p2, p3) = abs . ccArea . swapForCounterClockwise . sortOn fst $ [p1, p2, p3]
     where
         swapForCounterClockwise [a, b, c] = if snd a < snd b
                                                then [a, b, c]
@@ -50,9 +60,19 @@ getRandomTriangle image gen =
     . iterate (snd . next) $ gen
     
 getPointsInTriangle :: Image_ -> Triangle -> [Point]
-getPointsInTriangle image triangle
-    = filter (isPointInTriangle triangle)
-    $ (,) <$> [0..(rows image)] <*> [0..(cols image)]
+getPointsInTriangle image (p1', p2', p3') = (ptsBtween (p1, p3) (p1, p2)) ++
+                                            (ptsBtween (p1, p3) (p2, p3))
+    where
+        sortedPoints = sortOn snd [p1', p2', p3']
+
+        p1 = sortedPoints !! 0
+        p2 = sortedPoints !! 1
+        p3 = sortedPoints !! 2
+
+-- getPointsInTriangle image triangle =
+    -- = filter (isPointInTriangle triangle)
+    -- $ (,) <$> [0..(rows image)] <*> [0..(cols image)]
+    
 
 
 
@@ -74,6 +94,48 @@ getTriangleAverageRGB image triangle = blendEqually . map tosRGB' $  pixels
         points :: [Point]
         points = getPointsInTriangle image triangle
 
+-- pointsInTriangle image (p1, p2, p3) = 
+--     where
+--         sortedPts = sortOn snd [p1, p2, p3]
+
+ptsBtween :: (Point, Point) -> (Point, Point) -> [Point]
+ptsBtween (l1p1, l1p2) (l2p1, l2p2) = concatMap rasterLine [startingX .. endingX]
+    where
+        l1 = makeLine l1p1 l1p2
+        l2 = makeLine l2p1 l2p2
+
+        l1Xs = map snd [l1p1, l1p2]
+        l2Xs = map snd [l2p1, l2p2]
+
+        startingX = max (minimum l1Xs) (minimum l2Xs)
+        endingX   = min (maximum l1Xs) (maximum l2Xs)
+
+        rasterLine x = map (\y -> (y, x)) $ range' (yAt l1 x) (yAt l2 x)
+
+        
+
+        
+range' :: Int -> Int -> [Int]
+range' a b = [(min a b) .. (max a b)]
+
+yAt :: Line -> Int -> Int
+yAt (Line {m = m, b = b}) x = round $ (m * (fromIntegral x)) + b
+
+-- y = mx + b
+-- y - mx = b
+makeLine :: Point -> Point -> Line
+makeLine (y1, x1) (y2, x2) = Line {m = slope, b = (fromIntegral y1) - (slope * (fromIntegral x1))}
+    where
+        slope = (y1 - y2) `doubleDiv` (x1 - x2)
+
+doubleDiv a b = (fromIntegral a) / (fromIntegral b)
+
+data Line = Line
+    {
+        m :: Double,
+        b :: Double
+    }
+
 isPointInTriangle :: Triangle -> Point -> Bool
 isPointInTriangle (v1, v2, v3) pt = not (has_neg && has_pos)
     where