//1-input
#ifdef GL_ES
precision mediump float;
#endif

varying vec2 v_texcoord;
uniform sampler2D u_tex0;
uniform sampler2D u_tex1;
uniform vec2 u_resolution;
uniform float u_time;
uniform float u_x0;
uniform float u_x1;
uniform float u_x2;
uniform float u_x3;

vec4 rotate(sampler2D tex, vec2 pos){

    vec4 texColourRotate;
    vec2 center;
    //center = vec2(u_x3 / u_resolution.x, u_x4 / u_resolution.y);
    center = vec2(0.45 + 0.1*u_x1,0.45 + 0.1*u_x2);

    pos.x = (pos.x - center.x)*(0.5 / (0.45 + 0.1*u_x3)) + center.x;
    pos.y = (pos.y - center.y)*(0.5 / (0.45 + 0.1*u_x3)) + center.y;

    float r = distance(center, pos);
    float a = atan(pos.x - center.x, pos.y - center.y);

    pos.x = r * cos(a + 2.0 * 3.141592 * (0.2 + 0.1*u_x0)) + 0.5;
    pos.y = r * sin(a + 2.0 * 3.141592 * (0.2 + 0.1*u_x0)) + 0.5;
    pos.x = 1.0 - pos.x;
    if((pos.x < 0.0)||(pos.y < 0.0)||(pos.x > 1.0)||(pos.y > 1.0)){
        texColourRotate = vec4(0.0);
    }
    else{
        texColourRotate = texture2D(tex, pos);
    }
    return texColourRotate;
}

void main(){

    vec2 pos = v_texcoord;
    vec4 texColour0;
    texColour0 = rotate(u_tex0, v_texcoord);

    gl_FragColor = texColour0; 

}