Shadertoy: matrix rotation for uv.

Today I wrote a simple example in shadertoy about how to apply a rotation using rotation matrices with sin and cos for a uv, see wikipedia.

For uv I used already defined uv. I created a stripe using the modulo function to make rotation visible and completed the rotation with the iTime variable defined in shadertoy to rotate it continuously.

Here is the created source code:

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    //set the uv to a proper size on the center of screen 
    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / min(iResolution.x, iResolution.y);
    // set rotation angle value
    float rot = radians(0.0);
    // this set rotation by time and 
    rot = iTime;a
    // algebra formula for rotation by matrix , https://en.wikipedia.org/wiki/Rotation_matrix
    mat2 m = mat2(cos(rot), -sin(rot), sin(rot), cos(rot));
    // rotation of uv with matrix algebra formula where is set the rotation angle 
    uv = m* uv;
    // define float by function module from 1.0 and uv.x - uv.y
    float d = mod(uv.x - uv.y, 1.0);
    // color for fragColor is value of fload d by module function
    vec4 col = vec4(vec3(d), 1.0);
    fragColor = vec4(col);
}

Here is an example share from my shadertoy account.