Shader compilation in GitHub Actions

This patch sets up very basic CI (right now just cargo fmt) but more importantly compiles shaders in a GitHub Action.

Any PR to branches other than main will run shader compilation. Any push to the dev branch will run shader compilation and then merge to main.

Closes #177

.github/actions/shader/action.yml

@@ -0,0 +1,22 @@
+name: compile shaders
+
+runs:
+  using: 'composite'
+  steps:
+    - uses: seanmiddleditch/gha-setup-ninja@master
+
+    - name: setup SPIRV tools
+      # consider install-vulkan-sdk instead
+      uses: humbletim/setup-vulkan-sdk@v1.2.0
+      with:
+        vulkan-query-version: 1.3.204.0
+        vulkan-components: Glslang, SPIRV-Cross
+        vulkan-use-cache: true
+
+    - name: install DXC
+      uses: napokue/setup-dxc@v1.0.0
+
+    - name: run shader compilers
+      run: ninja
+      shell: pwsh
+      working-directory: piet-gpu/shader

.github/workflows/ci.yml

@@ -0,0 +1,27 @@
+on:
+  push:
+    branches:
+      - main
+      - dev
+  pull_request:
+
+jobs:
+  rustfmt:
+    runs-on: ubuntu-latest
+    name: cargo fmt
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          components: rustfmt
+          override: true
+
+      - name: cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check

.github/workflows/push-shader.yml

@@ -0,0 +1,37 @@
+on:
+  push:
+    branches:
+      - dev
+
+jobs:
+  push-shaders:
+    runs-on: windows-latest
+    name: compile shaders and push to main
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          # need history to make the merge work
+          # possibly we can optimize this and set
+          # allow-unrelated-histories on merge
+          fetch-depth: 0
+      - name: prepare repo for compilation
+        run: |
+          git fetch origin main
+          git switch main
+          git merge dev -m "merge from dev branch"
+          git rm -r --ignore-unmatch piet-gpu/shader/gen
+          mkdir piet-gpu/shader/gen
+      - uses: ./.github/actions/shader
+      - name: commit
+        id: commit
+        continue-on-error: true
+        run: |
+          git add piet-gpu/shader/gen
+          git config user.name "Commit by GitHub Action"
+          git config user.email "nobody@example.com"
+          git commit -m "commit compiled shaders"
+      - name: push
+        if: steps.commit.outcome == 'success'
+        run: |
+          git show-ref
+          git push origin main

.github/workflows/shader.yml

@@ -0,0 +1,13 @@
+on:
+  pull_request:
+    branches-ignore:
+     - main
+
+jobs:
+  push-shaders:
+    runs-on: windows-latest
+    name: compile shaders
+    steps:
+      - uses: actions/checkout@v3
+      - run: mkdir piet-gpu/shader/gen
+      - uses: ./.github/actions/shader