f=fopen(filename, "r");

    min_x=min_y=min_z=FLT_MAX;

    max_x=max_y=max_z=-FLT_MAX;

    while(!feof(f)){
        fread(&x, sizeof(x), 1, f);
        fread(&y, sizeof(y), 1, f);
        fread(&z, sizeof(z), 1, f);
        fread(&l_type, sizeof(l_type), 1, f);

        if(x<min_x){
            min_x=x;
        }else if(x>max_x){
            max_x=x;
        }

        if(y<min_y){
            min_y=y;
        }else if(y>max_y){
            max_y=y;
        }

        if(z<min_z){
            min_z=z;
        }else if(z>max_z){
            max_z=z;
        }
    }

    fclose(f);

    *a_min_x=min_x;
    *a_max_x=max_x;
    *a_min_y=min_y;
    *a_max_y=max_y;
    *a_min_z=min_z;
    *a_max_z=max_z;