From b192d6a5c4ed78af2155df9de9608607af769f81 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@me.com>
Date: Mon, 6 Jan 2020 14:16:32 -0500
Subject: [PATCH 1/2] Copute sweep &c. in the shader.

---
 src/Starlight/Draw/Radar.hs | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/Starlight/Draw/Radar.hs b/src/Starlight/Draw/Radar.hs
index ea9b9828..482e5d70 100644
--- a/src/Starlight/Draw/Radar.hs
+++ b/src/Starlight/Draw/Radar.hs
@@ -119,15 +119,30 @@ verticesForShips cs =
   ]
 
 
+instanceCount :: Int
+instanceCount = 1
+
+
 shader :: Shader U V O
 shader = program $ \ u
-  ->  vertex (\ V{ there, colour } IF{ colour2 = out } -> do
-    pos   <- let' "pos"   ((there - here u) D.^* (1/D.norm (there - here u)))
+  ->  vertex (\ V{ there, r, colour } IF{ colour2 = out } -> do
+    there <- let' "there" (there - here u)
+    d     <- let' "d"     (D.norm there)
+    dir   <- let' "dir"   (there D.^* (1/D.norm there))
+    let perp v = vec2 (negate (v D.^.D._y)) (v D.^.D._x)
+        angleOf vec = atan2' (vec D.^.D._y) (vec D.^.D._x)
+        wrap mn mx x = ((x + mx) `mod'` (mx - mn)) + mn
+    edge  <- let' "edge"  (perp dir D.^* r + dir D.^* d)
+    angle <- let' "angle" (angleOf there)
+    sweep <- let' "sweep" (minSweep `D.max'` (abs (wrap (-pi) pi (angleOf edge - angle))))
+    theta <- let' "theta" (angle + (float gl_InstanceID / fromIntegral instanceCount) * sweep)
+    pos   <- let' "pos"   (vec2 (cos theta) (sin theta))
     gl_PointSize .= 3
     out .= colour
     gl_Position .= ext4 (ext3 ((matrix u !* ext3 pos 1) D.^. D._xy) 0) 1)
 
-  >>> fragment (\ IF{ colour2 } O{ fragColour } -> fragColour .= colour2)
+  >>> fragment (\ IF{ colour2 } O{ fragColour } -> fragColour .= colour2) where
+  minSweep = 0.0133 -- at radius'=150, makes approx. 4px blips
 
 
 data U v = U

From eb9c3d707e971ce1f689b1af07086ce703f59c79 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@me.com>
Date: Mon, 6 Jan 2020 15:25:33 -0500
Subject: [PATCH 2/2] =?UTF-8?q?Revert=20"This=20doesn=E2=80=99t=20work."?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This reverts commit ff0624eeec7e298bfe7d1de4a7d624bd803545a4.
---
 .github/workflows/haskell.yml | 62 +++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 .github/workflows/haskell.yml

diff --git a/.github/workflows/haskell.yml b/.github/workflows/haskell.yml
new file mode 100644
index 00000000..d7a5ba7e
--- /dev/null
+++ b/.github/workflows/haskell.yml
@@ -0,0 +1,62 @@
+name: Haskell CI
+
+on:
+  # Trigger the workflow on push or pull request,
+  # but only for the master branch
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build:
+    name: ghc ${{ matrix.ghc }}
+    runs-on: ubuntu-16.04
+    strategy:
+      matrix:
+        ghc: ["8.8.1"]
+        cabal: ["3.0"]
+
+    steps:
+    - uses: actions/checkout@v2
+      if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/master'
+
+    - uses: actions/setup-haskell@v1
+      name: Setup Haskell
+      with:
+        ghc-version: ${{ matrix.ghc }}
+        cabal-version: ${{ matrix.cabal }}
+
+    # We cache the elements of the Cabal store separately,
+    # as the entirety of ~/.cabal can grow very large
+    # for projects with many dependencies.
+
+    - uses: actions/cache@v1
+      name: Cache ~/.cabal/packages
+      with:
+        path: ~/.cabal/packages
+        key: ${{ runner.os }}-${{ matrix.ghc }}-cabal-packages
+    - uses: actions/cache@v1
+      name: Cache ~/.cabal/store
+      with:
+        path: ~/.cabal/store
+        key: ${{ runner.os }}-${{ matrix.ghc }}-cabal-store
+    - uses: actions/cache@v1
+      name: Cache dist-newstyle
+      with:
+        path: dist-newstyle
+        key: ${{ runner.os }}-${{ matrix.ghc }}-dist-newstyle
+
+    - name: Install sdl2
+      run: |
+        sudo apt-get install libsdl2-dev
+
+    - name: Install dependencies
+      run: |
+        cabal v2-update
+        cabal v2-configure --enable-tests --enable-documentation --write-ghc-environment-files=always
+        cabal v2-build --only-dependencies
+    - name: Build & test
+      run: |
+        cabal v2-build
+        echo 'No tests'