Rotate Loop Square

#ifdef GL_ES
precision mediump float;
#define GLSLIFY 1
#endif

uniform vec2 u_resolution;
uniform float u_time;
uniform vec2 u_mouse;

#define GLSLIFY 1
mat2 rotate2d(float _angle){
    return mat2(cos(_angle),-sin(_angle), sin(_angle),cos(_angle));
}

float random (vec2 st) {
    return fract(sin(dot(st.xy, vec2(12.9898,78.233)))*43758.5453123);
}

#define M_SQRT_2 1.41421356
float square(vec2 P, float size){
    return abs(max(abs(P.x), abs(P.y)) - size/(2.0*M_SQRT_2));
}

float glow(float d, float str, float thickness){
    return thickness / pow(d, str);
}

void main() {
    vec2 uv = gl_FragCoord.xy/u_resolution.xy;
    // uv.x *= u_resolution.x/u_resolution.y;
    
    //grid repetition
    vec2 uvs=uv*6.;
    vec2 ipos = floor(uvs);  // get the integer coords
    vec2 fpos = fract(uvs);  // get the fractional coords
    uv= fpos*2.0-1.0;
    uv*= rotate2d(random(ipos)*3.14159+u_time*0.5);

    //drawing distance function 
    float draw = square(uv, 0.362);//sdFish(1.0, uv, 0.1), 
        // square(uv, 0.362), heart(uv, 0.5)    
    //float glow_draw = smoothstep(0.003,0.00,draw); //1st method
    float glow_draw = glow(draw, 0.5, 0.076); //2nd method
    //float glow_draw = exp(-draw*800.0); //3rd method

    gl_FragColor = vec4(vec3(glow_draw),1.0);
}