#ifdef GL_ES precision mediump float; #endif uniform vec2 u_resolution; uniform float u_time; float plot(vec2 st, float pct){ return smoothstep( pct-0.02, pct, st.y) - smoothstep( pct, pct+0.02, st.y); } void main() { vec2 st = gl_FragCoord.xy/u_resolution; float y = sin(st.x*u_time); float pct = plot(st,y); vec3 color = pct*vec3(0.0,1.0,0.0); gl_FragColor = vec4(color,1.0); }