Server.Engines.Craft.CraftItem.GetExceptionalChance C# (CSharp) Method

        public double GetExceptionalChance(CraftSystem system, double chance, Mobile from)
        {
            if (m_ForceNonExceptional)
                return 0.0;

            double bonus = 0.0;

            switch (system.ECA)
            {
                default:
                case CraftECA.ChanceMinusSixty: chance -= 0.6; break;
                case CraftECA.FiftyPercentChanceMinusTenPercent: chance = chance * 0.5 - 0.1; break;
                case CraftECA.ChanceMinusSixtyToFourtyFive:
                    {
                        double offset = 0.60 - ((from.Skills[system.MainSkill].Value - 95.0) * 0.03);

                        if (offset < 0.45)
                            offset = 0.45;
                        else if (offset > 0.60)
                            offset = 0.60;

                        chance -= offset;
                        break;
                    }
            }

            if (chance > 0)
                return chance + bonus;

            return chance;
        }

        public void DrawSkill()
        {
            for (int i = 0; i < m_CraftItem.Skills.Count; i++)
            {
                CraftSkill skill = m_CraftItem.Skills.GetAt(i);
                double     minSkill = skill.MinSkill, maxSkill = skill.MaxSkill;

                if (minSkill < 0)
                {
                    minSkill = 0;
                }

                AddHtmlLocalized(170, 132 + (i * 20), 200, 18, 1044060 + (int)skill.SkillToMake, LabelColor, false, false);
                AddLabel(430, 132 + (i * 20), LabelHue, String.Format("{0:F1}", minSkill));
            }

            CraftSubResCol res      = (m_CraftItem.UseSubRes2 ? m_CraftSystem.CraftSubRes2 : m_CraftSystem.CraftSubRes);
            int            resIndex = -1;

            CraftContext context = m_CraftSystem.GetContext(m_From);

            if (context != null)
            {
                resIndex = (m_CraftItem.UseSubRes2 ? context.LastResourceIndex2 : context.LastResourceIndex);
            }

            bool   allRequiredSkills = true;
            double chance            = m_CraftItem.GetSuccessChance(m_From, resIndex > -1 ? res.GetAt(resIndex).ItemType : null, m_CraftSystem, false, ref allRequiredSkills);

            double excepChance = m_CraftItem.GetExceptionalChance(m_CraftSystem, chance, m_From);

            if (chance < 0.0)
            {
                chance = 0.0;
            }
            else if (chance > 1.0)
            {
                chance = 1.0;
            }

            if (excepChance < 0.0)
            {
                excepChance = 0.0;
            }
            else if (excepChance > 1.0)
            {
                excepChance = 1.0;
            }

            AddHtmlLocalized(170, 80, 250, 18, 1044057, LabelColor, false, false);               // Success Chance:
            AddLabel(430, 80, LabelHue, String.Format("{0:F1}%", chance * 100));

            if (m_ShowExceptionalChance)
            {
                AddHtmlLocalized(170, 100, 250, 18, 1044058, 32767, false, false);                   // Exceptional Chance:
                AddLabel(430, 100, LabelHue, String.Format("{0:F1}%", excepChance * 100));
            }
        }