//uniform float scale_factor = 12;
uniform float scroll_speed;
uniform texture overlay;
uniform float overlay_mix = 0.8;
uniform float overlay_texture_width = 610;

vec4 base_texture = tex(TEXTURE, UV);
//vec4 overlay_texture = tex(overlay, ((UV * scale_factor) + (vec2(-scroll_speed * scale_factor, 0) * TIME)));
vec4 overlay_texture = tex(overlay, UV + (vec2(mod(scroll_speed * TIME, overlay_texture_width) * 0.00125, 0)));

if (overlay_texture.a > 0) {
    overlay_texture.a *= overlay_mix;
    COLOR.rgb = mix(overlay_texture.rgb, base_texture.rgb, (1.0 - overlay_texture.a));
} else {
    COLOR.rgb = base_texture.rgb;
}

COLOR.a = base_texture.a;