varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform float progress;
uniform vec2  detail;

uniform vec2  u_resolution;
uniform vec2  position;
uniform vec2  scale;

void main() {
    vec2 uv = (v_vTexcoord + position) * scale;
    
    for(float i = detail.x; i <= detail.y; i++) {
        uv.x += .5 / i * sin(i * 3. * uv.y + progress);
        uv.y += .3 / i * cos(i * 3. * uv.x + progress);
    }
    
    float a = .5 + .5 * sin(uv.x);
    gl_FragColor = vec4(vec3(a), 1.);
}