const float PI = 3.1415926; void main() { vec3 color = vec3(0.); vec2 st = gl_FragCoord.xy / u_resolution; // scale st to better fit card // (not in actual card code) st = (st - .5) * 1.09 + .5; st.y *= u_resolution.y / u_resolution.x; st.y -= (u_resolution.y * .5 - u_resolution.x * .5) / u_resolution.x; color += step(.5 + cos(st.y * PI) * .25, st.x); gl_FragColor = vec4(color, 1.); }