require 'glrb'
include Glrb

gl = GL.new 1280, 800
gl <=> ->{
  st = gl.FragCoord.xy / vec(gl.w, gl.h)
  vec st.x, st.y, 0.0, 1.0
}
gl.draw

require 'glrb'
include Glrb

gl = GL.new 1280, 800
gl <=> ->{
  a = vec 1.0, 1.0, 0.0
  b = vec 0.0, 1.0, 1.0
  c = vec 0.1, 0.2, 0.1
  col = vec 0.0, 0.0, 0.0
  st = gl.FragCoord.xy / vec(gl.w, gl.h)
  x = st.x * 5.0
  w = 0.01
  col += a * stroke st.y, sin(x) * 0.3 + 0.5, w
  col += b * stroke st.y, cos(x) * 0.2 + 0.5, w
  col += c * stp grid(st.x, w * 0.5, 0.1) + \
                 grid(st.y, w * 0.5, 0.1), 0.5 \
  vec col.x, col.y, col.z, 1.0
}
gl.draw

require 'glrb'
include Glrb

gl = GL.new 64, 64, "noise.ppm"

gl <=> ->{
  x = gl.FragCoord.x / gl.w
  y = gl.FragCoord.y / gl.h
  pos = vec(x, y, 0.0)
  col = snoise(pos) * 0.5 + 0.5
  gl.FragColor = vec col, col, col, 1.0
}

gl.draw

require 'glrb'
include Glrb

gl = GL.new 64, 64, "fbm.ppm"

gl <=> ->{
  x = gl.FragCoord.x / gl.w
  y = gl.FragCoord.y / gl.h
  pos = vec(x, y, 0.0)
  col = fbm(pos) * 0.5 + 0.5
  gl.FragColor = vec col, col, col, 1.0
}

gl.draw