SDF: GPU screensaver implemented in Haskell

SDF is a GPU screensaver implemented in Haskell.

It uses 2D signed distance functions to define primitive shapes and shape combinators, and renders them anti-aliased.

The simple Javascript client downloads new randomly-generated animated shapes from the server every five seconds, seamlessly blending them in the browser, resulting in an animation that never repeats.

It's built around a DSL that compiles pixel shaders to GLSL. It's core expression type is not refined by a GLSL type, so some type errors are caught by the DSL's crude typechecker, and the rest by the GLSL compiler.

The above animation is:

filaoa :: Shape
filaoa = scale 0.1 $ smoothUnion (scale (time / 10.0) filaoa') (rotation (time / 10.0) filaoa')
  where filaoa' = pfGrid 2.25 2.25 circle

Which is compiled into:

"vec4 x0 = (vec4((0.0), (0.0), (0.0), (1.0)));
float x1 = ((((((((((uv))/((1.0))))/((0.1))))/((((time))/((10.0))))).x))/((2.25)));
float x2 = (floor((x1)));
float x3 = (x2);
float x4 = (mod((abs((x3))), (2.0)));
float x5 = (((((x1))+((-(x2)))))*((2.25)));
float x6 = (((((x4))==((1.0))))?((((2.25))+((-(x5))))):((x5)));
float x7 = ((((((((((uv))/((1.0))))/((0.1))))/((((time))/((10.0))))).y))/((2.25)));
[... continues ...]

Live demo here.

TODO:

• Add a GLSL type parameter to the main expression type to support (and typecheck) GLSL ad-hoc polymorphism
• Monad comprehensions for loops

Thanks to https://twgljs.org/.