GLSL 紋理旋轉

vec2 texture_rotate(in vec2 uv,in float radin){

    // float radin=radians(90.0); //轉弧度
    float s = sin(radin);
    float c = cos(radin);
    mat2 rotationMatrix = mat2( c, s,-s,  c);
    vec2 pivot = vec2( 0.5, 0.5);
    vec2 result = rotationMatrix * (uv - pivot) + pivot;
    return result;
    
}