-- | Graphics algorithms and utils for rendering things in 2D space
--------------------------------------------------------------------------------
module Xanthous.Util.Graphics
( circle
, filledCircle
, line
) where
--------------------------------------------------------------------------------
import Xanthous.Prelude
import Data.List (unfoldr)
import Data.Ix (range, Ix)
import Data.Word (Word8)
import qualified Graphics.Rasterific as Raster
import Graphics.Rasterific hiding (circle, line)
import Graphics.Rasterific.Texture (uniformTexture)
import Codec.Picture (imagePixels)
--------------------------------------------------------------------------------
circle :: (Num i, Integral i, Ix i)
=> (i, i) -- ^ center
-> i -- ^ radius
-> [(i, i)]
circle (ox, oy) radius
= pointsFromRaster (ox + radius) (oy + radius)
$ stroke 1 JoinRound (CapRound, CapRound)
$ Raster.circle (V2 (fromIntegral ox) (fromIntegral oy))
$ fromIntegral radius
filledCircle :: (Num i, Integral i, Ix i)
=> (i, i) -- ^ center
-> i -- ^ radius
-> [(i, i)]
filledCircle (ox, oy) radius
= pointsFromRaster (ox + radius) (oy + radius)
$ fill
$ Raster.circle (V2 (fromIntegral ox) (fromIntegral oy))
$ fromIntegral radius
-- showCells . fromPoints . NE.fromList $ filledCircle (15, 15) 7
-- pointsFromRaster :: (Num i, Integral i, Ix i)
-- => i -- ^ width
-- -> i -- ^ height
-- -> _
-- -> [(i, i)]
pointsFromRaster
:: (Integral a, Integral b, Ix a, Ix b)
=> a
-> b
-> Drawing Word8 ()
-> [(a, b)]
pointsFromRaster w h raster
= map snd
$ filter ((== 1) . fst)
$ zip pixels
$ range ((1, 1), (w, h))
where
pixels = toListOf imagePixels
$ renderDrawing @Word8 (fromIntegral w) (fromIntegral h) 0
$ withTexture (uniformTexture 1) raster
-- | Draw a line between two points using Bresenham's line drawing algorithm
--
-- Code taken from <https://wiki.haskell.org/Bresenham%27s_line_drawing_algorithm>
line :: (Num i, Ord i) => (i, i) -> (i, i) -> [(i, i)]
line pa@(xa, ya) pb@(xb, yb)
= (if maySwitch pa < maySwitch pb then id else reverse) points
where
points = map maySwitch . unfoldr go $ (x₁, y₁, 0)
steep = abs (yb - ya) > abs (xb - xa)
maySwitch = if steep then swap else id
[(x₁, y₁), (x₂, y₂)] = sort [maySwitch pa, maySwitch pb]
δx = x₂ - x₁
δy = abs (y₂ - y₁)
ystep = if y₁ < y₂ then 1 else -1
go (xTemp, yTemp, err)
| xTemp > x₂ = Nothing
| otherwise = Just ((xTemp, yTemp), (xTemp + 1, newY, newError))
where
tempError = err + δy
(newY, newError) = if (2 * tempError) >= δx
then (yTemp + ystep, tempError - δx)
else (yTemp, tempError)
