// Classic interference plasma. Try changing the 6.0s and the 1.4.
void main() {
  vec2 uv = (gl_FragCoord.xy - 0.5 * u_resolution) / u_resolution.y;
  float t = u_time * 0.4;

  float v = sin(uv.x * 6.0 + t)
          + sin(uv.y * 6.0 - t)
          + sin((uv.x + uv.y) * 5.0 + t * 1.3)
          + sin(length(uv * 4.0) - t * 2.0);

  vec3 col = 0.5 + 0.5 * cos(vec3(0.0, 2.0, 4.0) + v * 1.4 + t);
  fragColor = vec4(col, 1.0);
}