uniform sampler2D texture;
uniform float iTime;

void main() {
    vec2 uv = gl_TexCoord[0].xy;
    float sine = sin(uv.x*24.0 - iTime*7.0);
    float offset = sine*0.04;
    uv.x -= 0.25;
    uv.x += offset*0.5*uv.x;
    uv.y += offset*uv.x*2.0 - 0.25;

    vec4 col = texture2D(texture, uv*2.0);
    col.rgb *= 0.9;
    col.rgb += (0.1 * sine*(uv.x*2.0));

    if(uv.x < 0.0 || uv.x > 0.5 || uv.y < 0.0 || uv.y > 0.5)
        col.a = 0.0;

    gl_FragColor = col;
}