Hide visible scrolling in static noise

Randomize vertical position of staticNoise texel and add to
existing scrolling of noise texture (both horizontal and vertical;
faster in vertical direction)

.github/workflows/appimage.yml

@@ -0,0 +1,98 @@
+name: "ci"
+
+on:
+  push:
+    tags: "**"
+  workflow_dispatch:
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  appimage:
+    runs-on: ubuntu-18.04
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+      with:
+        submodules: true
+
+    - name: Install dependencies
+      run: |
+        sudo add-apt-repository -y ppa:beineri/opt-qt-5.15.2-bionic
+        sudo apt-get update -qq
+        sudo apt-get install -y \
+        build-essential make wget libgl1-mesa-dev \
+        qt515declarative qt515graphicaleffects \
+        qt515quickcontrols qt515quickcontrols2
+
+    - name: Download QT appimage builder
+      run: |
+        wget -c -O linuxdeployqt.AppImage \
+        https://github.com/probonopd/linuxdeployqt/releases/download/continuous/linuxdeployqt-continuous-x86_64.AppImage
+        chmod a+x linuxdeployqt.AppImage
+
+    - name: Build project
+      run: |
+        source /opt/qt*/bin/qt*-env.sh && \
+        qmake -v && \
+        qmake CONFIG+=release PREFIX=/usr && \
+        make -j$(nproc)
+
+    - name: Install to appdir
+      run: |
+        source /opt/qt*/bin/qt*-env.sh && \
+        make INSTALL_ROOT=appdir -j$(nproc) install
+
+    - name: Extract version number
+      run: |
+        # Extract version for linuxdeployqt to name the file. Use the tag as
+        # release name but remove prefix.
+        echo "VERSION=$(echo '${{ github.ref }}' | sed 's;.*/;;')" >> $GITHUB_ENV
+
+    - name: Build appimage directory
+      run: |
+        mkdir -p \
+        appdir/usr/bin \
+        appdir/usr/lib \
+        appdir/usr/share/applications \
+        appdir/usr/share/metainfo \
+        appdir/usr/share/icons/hicolor/128x128/apps
+
+        cp cool-retro-term appdir/usr/bin/
+        cp cool-retro-term.desktop appdir/usr/share/applications/
+        cp packaging/appdata/cool-retro-term.appdata.xml appdir/usr/share/metainfo/
+        cp app/icons/128x128/cool-retro-term.png appdir/usr/share/icons/hicolor/128x128/apps/
+        cp -r ./app/qml appdir/usr/
+        # Workaround for https://github.com/probonopd/linuxdeployqt/issues/78
+        cp -r ./qmltermwidget/QMLTermWidget appdir/usr/qml/
+
+        find appdir | sort
+
+    - name: Build appimage
+      run: |
+        source /opt/qt*/bin/qt*-env.sh && \
+        ./linuxdeployqt.AppImage appdir/usr/share/applications/cool-retro-term.desktop \
+        -verbose=1 -appimage \
+        -qmldir=./app/qml/ \
+        -qmldir=./qmltermwidget/
+      env:
+        # Unset environment variables
+        QTDIR:
+        QT_PLUGIN_PATH:
+        LD_LIBRARY_PATH:
+
+    - name: Upload release
+      uses: softprops/action-gh-release@v1
+      with:
+        body: appimage release
+        files: ./**/Cool_Retro_Term-*-x86_64.AppImage
+
+    - name: Clean up
+      if: always()
+      run: |
+        find appdir -executable -type f -exec ldd {} \; | grep " => /usr" | cut -d " " -f 2-3 | sort | uniq
+        make clean
+        rm -rf appdir

app/qml/ShaderTerminal.qml

@@ -243,6 +243,17 @@ Item {
              "  return outColor;
              }" +
 
+             //pseudo-random vector
+             //https://stackoverflow.com/a/10625698
+             "float random( vec2 p )
+             {
+                 vec2 K1 = vec2(
+                     23.14069263277926, // e^pi (Gelfond's constant)
+                     2.665144142690225 // 2^sqrt(2) (Gelfond-Schneider constant)
+                 );
+                 return fract( cos( dot(p,K1) ) * 12345.6789 );
+             }" +
+
              "void main() {" +
                  "vec2 cc = vec2(0.5) - qt_TexCoord0;" +
                  "float distance = length(cc);" +
@@ -281,7 +292,11 @@ Item {
                  : "") +
 
                  (jitter !== 0 || staticNoise !== 0 ?
-                     "vec4 noiseTexel = texture2D(noiseSource, scaleNoiseSize * coords + vec2(fract(time / 51.0), fract(time / 237.0)));"
+                 "vec4 noiseTexel = texture2D(
+                     noiseSource, scaleNoiseSize * coords
+                     + vec2(0.0, random(vec2(fract(time / 237.0), 822.9582)))
+                     + vec2(fract(time / 31.0), fract(time / 177.0))
+                 );"
                  : "") +
 
                  (jitter !== 0 ? "