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