fwatch line intersection

case C_INFO_LINEINTERSECTION:
{
    // Parse input
    char *input       = par[2];
    int input_length  = strlen(input);
    float point[8]   = {0};
    int point_index   = 0;
    int bracket_level = 0;
    int number_start  = -1;
    int input_index   = 0;

    for (int i=0; i<input_length && point_index<8; i++) {
        if (bracket_level==2 && isdigit(input[i]) && number_start==-1)
            number_start = i;

        if (number_start>=0 && (input[i]==',' || input[i]==']')) {
            if (input_index++ < 2) {
                char save            = input[i];
                input[i]             = '\0';
                point[point_index++] = (float)atof(input+number_start);
                input[i]             = save;
            }

            number_start = -1;
        }

        if (input[i]=='[')
            bracket_level++;

        if (input[i]==']') {
            bracket_level--;
            input_index = 0;
        }
    }


    // Calculate intersection
    float a = point[3] - point[1];
    float b = point[0] - point[2];
    float c = a * point[0] + b * point[1];

    float a1 = point[7] - point[5];
    float b1 = point[4] - point[6];
    float c1 = a1 * point[4] + b1 * point[5];

    double det = a*b1 - a1*b;

    if (det == 0) {
        QWrite("[0,0]", out);
    } else {
        char tmp[32] = "";
        sprintf(tmp, "[%.6f,%.6f]", (b1*c-b*c1)/det, (a*c1-a1*c)/det);
        QWrite(tmp, out);
    }
}
break;