A 15-second, looping motion-design showreel that runs as a native Android app. Every frame is drawn live in Kotlin on a Jetpack Compose Canvas, with two AGSL shaders on the GPU. There's no video file, no Lottie, no web view, and no keyframes: the whole reel is a pure function of time.

Designed and built with Claude Opus 5.5 in Claude Code.

▶ Watch the reel (MP4, 15 s, 60 fps): a capture from the Android emulator, attached to the v1.0 release.

⬇ Download the APK (1.6 MB, Android 13+) to run the reel on your own device.

A viewfinder overlay runs on top throughout: timecode, REC dot, rolling section labels and a progress bar. It's drawn in difference blend so it stays readable on both ink and paper.

• One draw pass per frame. Reel.render(drawScope, t) draws the whole frame from the time t alone. Nothing is simulated or stored between frames, which is what makes the reel loopable, scrubbable and freezable on any frame.
• Jetpack Compose DrawScope handles shapes, text, clipping, transforms, gradients and blend modes.
• AGSL shaders (Shaders.kt) run through Android's RuntimeShader:
  • FLUID: domain-warped fBm with metaballs, contour lines, an iris mask and a pixelate control.
  • POST: a full-frame lens pass applied as a RenderEffect on a graphicsLayer. It adds chromatic aberration that spikes on the beats, glitch slices at hard cuts, a vignette and film grain.
• Analytic particles (Particles.kt): each particle's position is a closed-form function of time. The title is rasterised once into an ALPHA_8 bitmap to get the particles' target points. Particles are drawn as motion-blurred streaks with four Canvas.drawLines calls per frame (one per colour) and additive blending, so nothing is allocated per frame.
• Typography (TextKit.kt): text layouts are cached, and animated text moves with transforms instead of being re-measured each frame. Caps are centred optically using measured cap heights.
• Global motion: a list of impact beats in Motion.kt drives both camera shake and the lens aberration, so they hit on the same beats.

app/src/main/java/com/example/showreel/
├── MainActivity.kt   Full-screen activity, frame clock, tap to restart
├── Reel.kt           Every scene, the HUD and the post-effect wiring
├── Shaders.kt        AGSL sources (fluid + lens)
├── Particles.kt      Analytic particle system
├── TextKit.kt        Text layout cache and optical cap centring
└── Motion.kt         Palette, timeline, impact beats, easing library

The app needs Android 13 (API 33) or later for RuntimeShader.

Prebuilt: install the signed release APK from the v1.0 release:

adb install motion-showreel-v1.0.apk

From source:

./gradlew :app:installDebug
adb shell am start -n com.showreel.reel/com.example.showreel.MainActivity

Tap anywhere to restart the reel.

./gradlew :app:assembleRelease builds a minified (R8) release APK. It's signed only if a keystore.properties file is present in the project root (storeFile, storePassword, keyAlias, keyPassword); otherwise it's left unsigned. That file is gitignored.

On an emulator, use host GPU rendering (hw.gpu.mode=host in the AVD's config.ini, or -gpu host). Headless emulators with gpu.mode=auto fall back to software rendering, which drops the frame rate from 60 fps to about 20–35.

Jump to any moment, freeze it, or turn off the lens pass. This is useful for screenshots:

adb shell am start -n com.showreel.reel/com.example.showreel.MainActivity \
  --ef seek 7.2 --ez freeze true --ez nopost true

All three fonts are licensed under the SIL Open Font License 1.1, and their licences are included in licenses/:

• Inter Tight (ExtraBold): kinetic caps
• Instrument Serif (Regular and Italic): accents and the title
• Geist Mono (Regular and SemiBold): HUD and captions

Claude Opus 5.5, working in Claude Code, did the concept, choreography, typography, AGSL shaders and Kotlin for this reel. It also verified the work on the Android emulator: it froze frames at chosen timestamps to review them, profiled the frame rate, and captured the recording.

The code is released under the MIT License. The fonts keep their own OFL licences (see above).