#define iChannel0 inputImageTexture
#define texture(a,b) texture2D(a,fract(b))
#define fragColor gl_FragColor
precision highp float;
varying highp vec2 textureCoordinate;
 uniform sampler2D inputImageTexture;
 uniform highp float iTime;
 

void main()
{
    
    vec2 uv = textureCoordinate;
	
	highp float y = (iTime - 1.0)/3.0;
	if(y < 0.5){
		if(uv.y > y+0.5){
			uv.y = y+0.5;
		}
	}else{
		if(uv.y < y-0.5){
			uv.y = y-0.5;
		}
	}


	fragColor = texture(iChannel0,uv);
    
}