This pertains to the post-processing patch. For the original README,
see README.fluxus.

Apologies
---------

Originally, all of this was intended as a quick hack to make some nice
visuals for a party, but then more people took interest in it so we
were forced to release the source.

So beware of the following things:
 - It may break or act oddly (especially if you use the shader
   functions already present in fluxus).
 - The code was never intended to live longer than a week.
   It's ugly and I know it.

Usage
-----

This patch allows you to apply a fragment shader to the final fluxus
output. The vertex shader is fixed in this version. By default, the
fragment shader is the identity function.

(pp-shader STRING) sets the current post-processing shader to the one
given. If compilation fails, the previous pp-shader remains active.

The fluxus output is handed to the shader through the sampler2D
uniform "tex", the current texture coordinates are assigned to the
vec2 "tc" by the vertex shader.

(pp-shader-identity) loads the identity fragment shader.

Additional uniforms can be pushed into the shader using (pp-shader-set! UNIFORMS).
UNIFORMS is a list of the form ("name1" value1 "name2"  value2 ...).