Demos

Every kernel below is cljrs source. Videos were rendered by bin/record (CPU) and bin/gpu-record (GPU). Run any of them locally with the commands under each section.

GPU (defn-gpu-pixel)

Kernels compile to WGSL and run on wgpu: Metal on macOS, Vulkan on Linux, DX12 on Windows, WebGPU in browsers. Numbers below are render throughput on an integrated Apple M3 at 640x360.

Plasma (demo_gpu/plasma.clj) · 252 fps

Waves (demo_gpu/waves.clj) · 402 fps

Mandelbrot (demo_gpu/mandelbrot.clj) · 150 fps with 8x SSAA

Raymarched 3D scene (demo_gpu/raymarch3d.clj) · 494 fps

Ray tracer (demo_gpu/raytrace.clj) · 421 fps with reflections + shadows

Volumetric clouds (demo_gpu/clouds.clj) · 287 fps

Curl-noise flow field (demo_gpu/flowfield.clj) · 135 fps

cargo run --release --features gpu-demo --bin gpu-demo -- demo_gpu/plasma.clj

Edit the .clj file while the window is open, the kernel recompiles on save. Run any of these in the browser on the GPU page.

CPU (defn-native)

JIT-compiled to machine code via MLIR and LLVM. One call per pixel per frame, run in parallel across CPU cores with rayon.

Mandelbrot

Burning ship fractal

Julia set

Newton fractal

Raymarched spheres

SDF scene

Ray tracer

Software rasterizer

Lorenz attractor

Double pendulum

Clifford attractor

Plasma

Voronoi cells

Metaballs

Electric charges

Domain warping

Waves

Moiré

Kaleidoscope

Truchet tiles

Phyllotaxis

cargo run --release --features demo --bin demo -- demo/fractal.clj

Live-coded browser demos

Edit cljrs source in the page, see the change reflected immediately. State persists across edits.

Platformer — pause, rewind, change jump height, see the future trajectory redraw.
Conway's Game of Life — edit birth/survive rules, neighborhood, palette; click cells to toggle.
Synth — polyphonic subtractive synth, live-editable ADSR + filter + LFO.
Sequencer — step sequencer wired to the synth.
ML — four training showcases (curve fit, two-moons, MNIST-tiny, autoencoder).
Matmul bench — cljrs CPU/GPU matmul vs numpy/JAX/PyTorch references.
UI demo — cljrs.ui = hiccup → Preact via wasm.
JS interop — fetch, local storage, DOM from cljrs.
Physics — rapier-driven 2D physics playground.

Kernel ABI

CPU kernels have a fixed signature:

(defn-native render-pixel ^i64
  [^i64 px ^i64 py ^i64 frame ^i64 t-ms
   ^i64 s0 ^i64 s1 ^i64 s2 ^i64 s3]
  ...body, returns 0xRRGGBB as i64...)

The host calls it once per pixel per frame, in parallel via rayon. s0 through s3 are slider values 0 to 1000. Time scrubbing replaces t-ms with a paused value.

Build your own

echo "(defn-native render-pixel ^i64
  [^i64 px ^i64 py ^i64 frame ^i64 t-ms
   ^i64 s0 ^i64 s1 ^i64 s2 ^i64 s3]
  (+ (* px 257) py))" > demo/stripes.clj

cargo run --release --features demo --bin demo -- demo/stripes.clj

Record to mp4

cargo run --release --features demo --bin record -- \
  --kernel demo/fractal.clj \
  --seconds 6 --fps 60 --size 960x540 \
  --out out/fractal.mp4