uniform float u_Time;
uniform sampler2D u_Tex0;
varying vec2 v_TexCoord;

void main()
{
  vec4 col = texture2D(u_Tex0, v_TexCoord);
  float d = u_Time * 0.7;
  col.x += (1.0 + sin(d)) * 0.25;
  col.y += (1.0 + sin(d * 2.0)) * 0.25;
  col.z += (1.0 + sin(d * 4.0)) * 0.25;
  gl_FragColor = col;
}
