looped.glsl

vec4 box = vec4(0.0, 0, 0.3, 0.3);

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
 	box.x += 0.05 * iTime;
    box.y -= 0.03 * iTime;
    // Normalized pixel coordinates (from 0 to 1)
    vec2 uv = fragCoord/iResolution.xy;
    
    vec2 looped = uv / box.zw;
    looped = uv - floor(looped) * box.zw;
    looped += box.xy;
    
    fragColor = texture(iChannel0, looped);
}