consolidate random number logic

Note, I suspect Rng::rollClosedProbability() is not needed.  The only difference between it and rollProbability() is that one time in 37k (on Windows), it will give an output of 1.0.
On some versions of Linux, the value of 1.0 will occur about 1 time in 4 billion.

apps/openmw/engine.cpp

@@ -10,6 +10,8 @@
 
 #include <SDL.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/compiler/extensions0.hpp>
 
 #include <components/bsa/resources.hpp>
@@ -191,6 +193,7 @@ OMW::Engine::Engine(Files::ConfigurationManager& configurationManager)
   , mExportFonts(false)
   , mNewGame (false)
 {
+    OEngine::Misc::Rng::init();
     std::srand ( static_cast<unsigned int>(std::time(NULL)) );
     MWClass::registerClasses();
 

apps/openmw/mwclass/creature.cpp

@@ -1,6 +1,8 @@
 
 #include "creature.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/loadcrea.hpp>
 #include <components/esm/creaturestate.hpp>
 
@@ -249,7 +251,7 @@ namespace MWClass
 
         float hitchance = MWMechanics::getHitChance(ptr, victim, ref->mBase->mData.mCombat);
 
-        if((::rand()/(RAND_MAX+1.0)) >= hitchance/100.0f)
+        if(OEngine::Misc::Rng::rollProbability() >= hitchance/100.0f)
         {
             victim.getClass().onHit(victim, 0.0f, false, MWWorld::Ptr(), ptr, false);
             MWMechanics::reduceWeaponCondition(0.f, false, weapon, ptr);
@@ -375,8 +377,7 @@ namespace MWClass
                 float agilityTerm = getCreatureStats(ptr).getAttribute(ESM::Attribute::Agility).getModified() * getGmst().fKnockDownMult->getFloat();
                 float knockdownTerm = getCreatureStats(ptr).getAttribute(ESM::Attribute::Agility).getModified()
                         * getGmst().iKnockDownOddsMult->getInt() * 0.01f + getGmst().iKnockDownOddsBase->getInt();
-                int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+                if (ishealth && agilityTerm <= damage && knockdownTerm <= OEngine::Misc::Rng::roll0to99())
-                if (ishealth && agilityTerm <= damage && knockdownTerm <= roll)
                 {
                     getCreatureStats(ptr).setKnockedDown(true);
 
@@ -680,7 +681,7 @@ namespace MWClass
                 ++sound;
             }
             if(!sounds.empty())
-                return sounds[(int)(rand()/(RAND_MAX+1.0)*sounds.size())]->mSound;
+                return sounds[OEngine::Misc::Rng::rollDice(sounds.size())]->mSound;
         }
 
         if (type == ESM::SoundGenerator::Land)

apps/openmw/mwclass/npc.cpp

@@ -5,6 +5,8 @@
 
 #include <OgreSceneNode.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/loadmgef.hpp>
 #include <components/esm/loadnpc.hpp>
 #include <components/esm/npcstate.hpp>
@@ -513,7 +515,7 @@ namespace MWClass
 
         float hitchance = MWMechanics::getHitChance(ptr, victim, ptr.getClass().getSkill(ptr, weapskill));
 
-        if((::rand()/(RAND_MAX+1.0)) >= hitchance/100.0f)
+        if (OEngine::Misc::Rng::rollProbability() >= hitchance / 100.0f)
         {
             othercls.onHit(victim, 0.0f, false, weapon, ptr, false);
             MWMechanics::reduceWeaponCondition(0.f, false, weapon, ptr);
@@ -643,8 +645,7 @@ namespace MWClass
             const GMST& gmst = getGmst();
 
             int chance = store.get<ESM::GameSetting>().find("iVoiceHitOdds")->getInt();
-            int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+            if (OEngine::Misc::Rng::roll0to99() < chance)
-            if (roll < chance)
             {
                 MWBase::Environment::get().getDialogueManager()->say(ptr, "hit");
             }
@@ -653,8 +654,7 @@ namespace MWClass
             float agilityTerm = getCreatureStats(ptr).getAttribute(ESM::Attribute::Agility).getModified() * gmst.fKnockDownMult->getFloat();
             float knockdownTerm = getCreatureStats(ptr).getAttribute(ESM::Attribute::Agility).getModified()
                     * gmst.iKnockDownOddsMult->getInt() * 0.01f + gmst.iKnockDownOddsBase->getInt();
-            roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+            if (ishealth && agilityTerm <= damage && knockdownTerm <= OEngine::Misc::Rng::roll0to99())
-            if (ishealth && agilityTerm <= damage && knockdownTerm <= roll)
             {
                 getCreatureStats(ptr).setKnockedDown(true);
 
@@ -680,7 +680,7 @@ namespace MWClass
                     MWWorld::InventoryStore::Slot_RightPauldron, MWWorld::InventoryStore::Slot_RightPauldron,
                     MWWorld::InventoryStore::Slot_LeftGauntlet, MWWorld::InventoryStore::Slot_RightGauntlet
                 };
-                int hitslot = hitslots[(int)(::rand()/(RAND_MAX+1.0)*20.0)];
+                int hitslot = hitslots[OEngine::Misc::Rng::rollDice(20)];
 
                 float unmitigatedDamage = damage;
                 float x = damage / (damage + getArmorRating(ptr));

apps/openmw/mwgui/jailscreen.cpp

@@ -1,5 +1,7 @@
 #include <MyGUI_ScrollBar.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwbase/windowmanager.hpp"
 #include "../mwbase/mechanicsmanager.hpp"
 #include "../mwbase/world.hpp"
@@ -83,7 +85,7 @@ namespace MWGui
         std::set<int> skills;
         for (int day=0; day<mDays; ++day)
         {
-            int skill = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * ESM::Skill::Length);
+            int skill = OEngine::Misc::Rng::rollDice(ESM::Skill::Length);
             skills.insert(skill);
 
             MWMechanics::SkillValue& value = player.getClass().getNpcStats(player).getSkill(skill);

apps/openmw/mwgui/loadingscreen.cpp

@@ -15,6 +15,8 @@
 #include <MyGUI_Gui.h>
 #include <MyGUI_TextBox.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/settings/settings.hpp>
 
 #include "../mwbase/environment.hpp"
@@ -146,7 +148,7 @@ namespace MWGui
 
         if (!mResources.empty())
         {
-            std::string const & randomSplash = mResources.at (rand() % mResources.size());
+            std::string const & randomSplash = mResources.at(OEngine::Misc::Rng::rollDice(mResources.size()));
 
             Ogre::TextureManager::getSingleton ().load (randomSplash, Ogre::ResourceGroupManager::AUTODETECT_RESOURCE_GROUP_NAME);
 

apps/openmw/mwgui/pickpocketitemmodel.cpp

@@ -1,5 +1,7 @@
 #include "pickpocketitemmodel.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwmechanics/npcstats.hpp"
 #include "../mwworld/class.hpp"
 
@@ -12,11 +14,13 @@ namespace MWGui
         int chance = thief.getClass().getSkill(thief, ESM::Skill::Sneak);
 
         mSourceModel->update();
+
+        // build list of items that player is unable to find when attempts to pickpocket.
         if (hideItems)
         {
             for (size_t i = 0; i<mSourceModel->getItemCount(); ++i)
             {
-                if (std::rand() / static_cast<float>(RAND_MAX) * 100 > chance)
+                if (chance <= OEngine::Misc::Rng::roll0to99())
                     mHiddenItems.push_back(mSourceModel->getItem(i));
             }
         }

apps/openmw/mwgui/recharge.cpp

@@ -5,6 +5,8 @@
 #include <MyGUI_ScrollView.h>
 #include <MyGUI_Gui.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/records.hpp>
 
 #include "../mwbase/world.hpp"
@@ -161,7 +163,7 @@ void Recharge::onItemClicked(MyGUI::Widget *sender)
         intelligenceTerm = 1;
 
     float x = (npcStats.getSkill(ESM::Skill::Enchant).getModified() + intelligenceTerm + luckTerm) * stats.getFatigueTerm();
-    int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+    int roll = OEngine::Misc::Rng::roll0to99();
     if (roll < x)
     {
         std::string soul = gem.getCellRef().getSoul();

apps/openmw/mwgui/tradewindow.cpp

@@ -4,6 +4,8 @@
 #include <MyGUI_InputManager.h>
 #include <MyGUI_ControllerManager.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/widgets/numericeditbox.hpp>
 
 #include "../mwbase/environment.hpp"
@@ -365,7 +367,7 @@ namespace MWGui
             else
                 x += abs(int(npcTerm - pcTerm));
 
-            int roll = std::rand()%100 + 1;
+            int roll = OEngine::Misc::Rng::rollDice(100) + 1;
             if(roll > x || (mCurrentMerchantOffer < 0) != (mCurrentBalance < 0)) //trade refused
             {
                 MWBase::Environment::get().getWindowManager()->

apps/openmw/mwgui/waitdialog.cpp

@@ -2,6 +2,8 @@
 
 #include <MyGUI_ProgressBar.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/widgets/box.hpp>
 #include <components/settings/settings.hpp>
 
@@ -152,10 +154,9 @@ namespace MWGui
                 const ESM::Region *region = world->getStore().get<ESM::Region>().find (regionstr);
                 if (!region->mSleepList.empty())
                 {
+                    // figure out if player will be woken while sleeping
                     float fSleepRandMod = world->getStore().get<ESM::GameSetting>().find("fSleepRandMod")->getFloat();
-                    int x = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * hoursToWait); // [0, hoursRested]
+                    if (OEngine::Misc::Rng::rollProbability() > fSleepRandMod)
-                    float y = fSleepRandMod * hoursToWait;
-                    if (x > y)
                     {
                         float fSleepRestMod = world->getStore().get<ESM::GameSetting>().find("fSleepRestMod")->getFloat();
                         mInterruptAt = hoursToWait - int(fSleepRestMod * hoursToWait);

apps/openmw/mwmechanics/activespells.cpp

@@ -1,5 +1,7 @@
 #include "activespells.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/misc/stringops.hpp>
 
 #include <components/esm/loadmgef.hpp>
@@ -229,8 +231,7 @@ namespace MWMechanics
     {
         for (TContainer::iterator it = mSpells.begin(); it != mSpells.end(); )
         {
-            int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+            if (OEngine::Misc::Rng::roll0to99() < chance)
-            if (roll < chance)
                 mSpells.erase(it++);
             else
                 ++it;

apps/openmw/mwmechanics/aicombat.cpp

@@ -2,6 +2,8 @@
 
 #include <OgreMath.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/aisequence.hpp>
 
 #include "../mwworld/class.hpp"
@@ -393,7 +395,7 @@ namespace MWMechanics
                 if (!distantCombat) attackType = chooseBestAttack(weapon, movement);
                 else attackType = ESM::Weapon::AT_Chop; // cause it's =0
 
-                strength = static_cast<float>(rand()) / RAND_MAX;
+                strength = OEngine::Misc::Rng::rollClosedProbability();
 
                 // Note: may be 0 for some animations
                 timerAttack = minMaxAttackDuration[attackType][0] + 
@@ -404,8 +406,7 @@ namespace MWMechanics
                 {
                     const MWWorld::ESMStore &store = world->getStore();
                     int chance = store.get<ESM::GameSetting>().find("iVoiceAttackOdds")->getInt();
-                    int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+                    if (OEngine::Misc::Rng::roll0to99() < chance)
-                    if (roll < chance)
                     {
                         MWBase::Environment::get().getDialogueManager()->say(actor, "attack");
                     }
@@ -512,17 +513,17 @@ namespace MWMechanics
             {
                 if(movement.mPosition[0] || movement.mPosition[1])
                 {
-                    timerCombatMove = 0.1f + 0.1f * static_cast<float>(rand())/RAND_MAX;
+                    timerCombatMove = 0.1f + 0.1f * OEngine::Misc::Rng::rollClosedProbability();
                     combatMove = true;
                 }
                 // only NPCs are smart enough to use dodge movements
                 else if(actorClass.isNpc() && (!distantCombat || (distantCombat && distToTarget < rangeAttack/2)))
                 {
                     //apply sideway movement (kind of dodging) with some probability
-                    if(static_cast<float>(rand())/RAND_MAX < 0.25)
+                    if (OEngine::Misc::Rng::rollClosedProbability() < 0.25)
                     {
-                        movement.mPosition[0] = static_cast<float>(rand())/RAND_MAX < 0.5? 1.0f : -1.0f;
+                        movement.mPosition[0] = OEngine::Misc::Rng::rollProbability() < 0.5 ? 1.0f : -1.0f;
-                        timerCombatMove = 0.05f + 0.15f * static_cast<float>(rand())/RAND_MAX;
+                        timerCombatMove = 0.05f + 0.15f * OEngine::Misc::Rng::rollClosedProbability();
                         combatMove = true;
                     }
                 }
@@ -637,7 +638,7 @@ namespace MWMechanics
                 float s2 = speed2 * t;
                 float t_swing = 
                     minMaxAttackDuration[ESM::Weapon::AT_Thrust][0] + 
-                    (minMaxAttackDuration[ESM::Weapon::AT_Thrust][1] - minMaxAttackDuration[ESM::Weapon::AT_Thrust][0]) * static_cast<float>(rand()) / RAND_MAX;
+                    (minMaxAttackDuration[ESM::Weapon::AT_Thrust][1] - minMaxAttackDuration[ESM::Weapon::AT_Thrust][0]) * OEngine::Misc::Rng::rollClosedProbability();
 
                 if (t + s2/speed1 <= t_swing)
                 {
@@ -761,10 +762,10 @@ ESM::Weapon::AttackType chooseBestAttack(const ESM::Weapon* weapon, MWMechanics:
     if (weapon == NULL)
     {
         //hand-to-hand deal equal damage for each type
-        float roll = static_cast<float>(rand())/RAND_MAX;
+        float roll = OEngine::Misc::Rng::rollClosedProbability();
         if(roll <= 0.333f)  //side punch
         {
-            movement.mPosition[0] = (static_cast<float>(rand())/RAND_MAX < 0.5f)? 1.0f : -1.0f;
+            movement.mPosition[0] = OEngine::Misc::Rng::rollClosedProbability() ? 1.0f : -1.0f;
             movement.mPosition[1] = 0;
             attackType = ESM::Weapon::AT_Slash;
         }
@@ -788,10 +789,10 @@ ESM::Weapon::AttackType chooseBestAttack(const ESM::Weapon* weapon, MWMechanics:
 
         float total = static_cast<float>(slash + chop + thrust);
 
-        float roll = static_cast<float>(rand())/RAND_MAX;
+        float roll = OEngine::Misc::Rng::rollClosedProbability();
         if(roll <= (slash/total))
         {
-            movement.mPosition[0] = (static_cast<float>(rand())/RAND_MAX < 0.5f)? 1.0f : -1.0f;
+            movement.mPosition[0] = (OEngine::Misc::Rng::rollClosedProbability() < 0.5f) ? 1.0f : -1.0f;
             movement.mPosition[1] = 0;
             attackType = ESM::Weapon::AT_Slash;
         }

apps/openmw/mwmechanics/aiwander.cpp

@@ -3,6 +3,8 @@
 #include <OgreVector3.h>
 #include <OgreSceneNode.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/aisequence.hpp>
 
 #include "../mwbase/world.hpp"
@@ -315,7 +317,7 @@ namespace MWMechanics
             static float fVoiceIdleOdds = MWBase::Environment::get().getWorld()->getStore()
                     .get<ESM::GameSetting>().find("fVoiceIdleOdds")->getFloat();
 
-            float roll = std::rand()/ (static_cast<float> (RAND_MAX) + 1) * 10000;
+            float roll = OEngine::Misc::Rng::rollProbability() * 10000.0f;
 
             // In vanilla MW the chance was FPS dependent, and did not allow proper changing of fVoiceIdleOdds
             // due to the roll being an integer.
@@ -490,7 +492,7 @@ namespace MWMechanics
             if(!storage.mPathFinder.isPathConstructed())
             {
                 assert(mAllowedNodes.size());
-                unsigned int randNode = (int)(rand() / ((double)RAND_MAX + 1) * mAllowedNodes.size());
+                unsigned int randNode = OEngine::Misc::Rng::rollDice(mAllowedNodes.size());
                 // NOTE: initially constructed with local (i.e. cell) co-ordinates
                 Ogre::Vector3 destNodePos(PathFinder::MakeOgreVector3(mAllowedNodes[randNode]));
 
@@ -637,7 +639,7 @@ namespace MWMechanics
                 .get<ESM::GameSetting>().find("fIdleChanceMultiplier")->getFloat();
 
             unsigned short idleChance = static_cast<unsigned short>(fIdleChanceMultiplier * mIdle[counter]);
-            unsigned short randSelect = (int)(rand() / ((double)RAND_MAX + 1) * int(100 / fIdleChanceMultiplier));
+            unsigned short randSelect = (int)(OEngine::Misc::Rng::rollProbability() * int(100 / fIdleChanceMultiplier));
             if(randSelect < idleChance && randSelect > idleRoll)
             {
                 playedIdle = counter+2;
@@ -659,7 +661,7 @@ namespace MWMechanics
 
         state.moveIn(new AiWanderStorage());
 
-        int index = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * mAllowedNodes.size());
+        int index = OEngine::Misc::Rng::rollDice(mAllowedNodes.size());
         ESM::Pathgrid::Point dest = mAllowedNodes[index];
 
         // apply a slight offset to prevent overcrowding

apps/openmw/mwmechanics/alchemy.cpp

@@ -8,6 +8,8 @@
 #include <stdexcept>
 #include <map>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/loadskil.hpp>
 #include <components/esm/loadappa.hpp>
 #include <components/esm/loadgmst.hpp>
@@ -294,7 +296,7 @@ void MWMechanics::Alchemy::addPotion (const std::string& name)
 
     newRecord.mName = name;
 
-    int index = static_cast<int> (std::rand()/(static_cast<double> (RAND_MAX)+1)*6);
+    int index = OEngine::Misc::Rng::rollDice(6);
     assert (index>=0 && index<6);
 
     static const char *meshes[] = { "standard", "bargain", "cheap", "fresh", "exclusive", "quality" };
@@ -467,7 +469,7 @@ MWMechanics::Alchemy::Result MWMechanics::Alchemy::create (const std::string& na
         return Result_RandomFailure;
     }
 
-    if (getAlchemyFactor()<std::rand()/static_cast<double> (RAND_MAX)*100)
+    if (getAlchemyFactor() < OEngine::Misc::Rng::roll0to99())
     {
         removeIngredients();
         return Result_RandomFailure;

apps/openmw/mwmechanics/character.cpp

@@ -27,6 +27,8 @@
 #include "creaturestats.hpp"
 #include "security.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/settings/settings.hpp>
 
 #include "../mwrender/animation.hpp"
@@ -220,7 +222,7 @@ std::string CharacterController::chooseRandomGroup (const std::string& prefix, i
     while (mAnimation->hasAnimation(prefix + Ogre::StringConverter::toString(numAnims+1)))
         ++numAnims;
 
-    int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * numAnims) + 1; // [1, numAnims]
+    int roll = OEngine::Misc::Rng::rollDice(numAnims) + 1; // [1, numAnims]
     if (num)
         *num = roll;
     return prefix + Ogre::StringConverter::toString(roll);
@@ -829,7 +831,7 @@ bool CharacterController::updateCreatureState()
             }
             if (weapType != WeapType_Spell || !mAnimation->hasAnimation("spellcast")) // Not all creatures have a dedicated spellcast animation
             {
-                int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 3); // [0, 2]
+                int roll = OEngine::Misc::Rng::rollDice(3); // [0, 2]
                 if (roll == 0)
                     mCurrentWeapon = "attack1";
                 else if (roll == 1)
@@ -1125,7 +1127,7 @@ bool CharacterController::updateWeaponState()
                 // most creatures don't actually have an attack wind-up animation, so use a uniform random value
                 // (even some creatures that can use weapons don't have a wind-up animation either, e.g. Rieklings)
                 // Note: vanilla MW uses a random value for *all* non-player actors, but we probably don't need to go that far.
-                attackStrength = std::min(1.f, 0.1f + std::rand() / float(RAND_MAX));
+                attackStrength = std::min(1.f, 0.1f + OEngine::Misc::Rng::rollClosedProbability());
             }
 
             if(mWeaponType != WeapType_Crossbow && mWeaponType != WeapType_BowAndArrow)

apps/openmw/mwmechanics/combat.cpp

@@ -2,6 +2,8 @@
 
 #include <OgreSceneNode.h>
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwbase/environment.hpp"
 #include "../mwbase/world.hpp"
 #include "../mwbase/mechanicsmanager.hpp"
@@ -107,8 +109,7 @@ namespace MWMechanics
         int iBlockMinChance = gmst.find("iBlockMinChance")->getInt();
         x = std::min(iBlockMaxChance, std::max(iBlockMinChance, x));
 
-        int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+        if (OEngine::Misc::Rng::roll0to99() < x)
-        if (roll < x)
         {
             // Reduce shield durability by incoming damage
             int shieldhealth = shield->getClass().getItemHealth(*shield);
@@ -186,7 +187,7 @@ namespace MWMechanics
         int skillValue = attacker.getClass().getSkill(attacker,
                                            weapon.getClass().getEquipmentSkill(weapon));
 
-        if((::rand()/(RAND_MAX+1.0)) >= getHitChance(attacker, victim, skillValue)/100.0f)
+        if (OEngine::Misc::Rng::rollProbability() >= getHitChance(attacker, victim, skillValue) / 100.0f)
         {
             victim.getClass().onHit(victim, 0.0f, false, projectile, attacker, false);
             MWMechanics::reduceWeaponCondition(0.f, false, weapon, attacker);
@@ -224,7 +225,7 @@ namespace MWMechanics
                 && !appliedEnchantment)
         {
             float fProjectileThrownStoreChance = gmst.find("fProjectileThrownStoreChance")->getFloat();
-            if ((::rand()/(RAND_MAX+1.0)) < fProjectileThrownStoreChance/100.f)
+            if (OEngine::Misc::Rng::rollProbability() < fProjectileThrownStoreChance / 100.f)
                 victim.getClass().getContainerStore(victim).add(projectile, 1, victim);
         }
 
@@ -291,8 +292,7 @@ namespace MWMechanics
 
             saveTerm *= 1.25f * normalisedFatigue;
 
-            float roll = std::rand()/ (static_cast<float> (RAND_MAX) + 1) * 100; // [0, 99]
+            float x = std::max(0.f, saveTerm - OEngine::Misc::Rng::roll0to99());
-            float x = std::max(0.f, saveTerm - roll);
 
             int element = ESM::MagicEffect::FireDamage;
             if (i == 1)

apps/openmw/mwmechanics/disease.hpp

@@ -1,6 +1,8 @@
 #ifndef OPENMW_MECHANICS_DISEASE_H
 #define OPENMW_MECHANICS_DISEASE_H
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwbase/windowmanager.hpp"
 #include "../mwbase/environment.hpp"
 #include "../mwbase/world.hpp"
@@ -49,9 +51,7 @@ namespace MWMechanics
                 continue;
 
             int x = static_cast<int>(fDiseaseXferChance * 100 * resist);
-            float roll = static_cast<float>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 10000); // [0, 9999]
+            if (OEngine::Misc::Rng::rollDice(10000) < x)
-
-            if (roll < x)
             {
                 // Contracted disease!
                 actor.getClass().getCreatureStats(actor).getSpells().add(it->first);

apps/openmw/mwmechanics/enchanting.cpp

@@ -1,4 +1,7 @@
 #include "enchanting.hpp"
+
+#include <openengine/misc/rng.hpp>
+
 #include "../mwworld/manualref.hpp"
 #include "../mwworld/class.hpp"
 #include "../mwworld/containerstore.hpp"
@@ -67,7 +70,7 @@ namespace MWMechanics
 
         if(mSelfEnchanting)
         {
-            if(getEnchantChance()<std::rand()/static_cast<double> (RAND_MAX)*100)
+            if(getEnchantChance() <= (OEngine::Misc::Rng::roll0to99()))
                 return false;
 
             mEnchanter.getClass().skillUsageSucceeded (mEnchanter, ESM::Skill::Enchant, 2);

apps/openmw/mwmechanics/levelledlist.hpp

@@ -1,6 +1,8 @@
 #ifndef OPENMW_MECHANICS_LEVELLEDLIST_H
 #define OPENMW_MECHANICS_LEVELLEDLIST_H
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwworld/ptr.hpp"
 #include "../mwworld/esmstore.hpp"
 #include "../mwworld/manualref.hpp"
@@ -22,8 +24,7 @@ namespace MWMechanics
 
         failChance += levItem->mChanceNone;
 
-        int random = static_cast<int>(static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100)); // [0, 99]
+        if (OEngine::Misc::Rng::roll0to99() < failChance)
-        if (random < failChance)
             return std::string();
 
         std::vector<std::string> candidates;
@@ -52,7 +53,7 @@ namespace MWMechanics
         }
         if (candidates.empty())
             return std::string();
-        std::string item = candidates[std::rand()%candidates.size()];
+        std::string item = candidates[OEngine::Misc::Rng::rollDice(candidates.size())];
 
         // Vanilla doesn't fail on nonexistent items in levelled lists
         if (!MWBase::Environment::get().getWorld()->getStore().find(Misc::StringUtils::lowerCase(item)))

apps/openmw/mwmechanics/mechanicsmanagerimp.cpp

@@ -2,6 +2,8 @@
 #include "mechanicsmanagerimp.hpp"
 #include "npcstats.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/stolenitems.hpp>
 
 #include "../mwworld/esmstore.hpp"
@@ -723,7 +725,7 @@ namespace MWMechanics
         float x = 0;
         float y = 0;
 
-        float roll = static_cast<float> (std::rand()) / RAND_MAX * 100;
+        float roll = OEngine::Misc::Rng::rollClosedProbability() * 100;
 
         if (type == PT_Admire)
         {
@@ -1378,9 +1380,8 @@ namespace MWMechanics
             y = obsTerm * observerStats.getFatigueTerm() * fSneakViewMult;
 
         float target = x - y;
-        int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
 
-        return (roll >= target);
+        return (OEngine::Misc::Rng::roll0to99() >= target);
     }
 
     void MechanicsManager::startCombat(const MWWorld::Ptr &ptr, const MWWorld::Ptr &target)

apps/openmw/mwmechanics/pickpocket.cpp

@@ -1,5 +1,7 @@
 #include "pickpocket.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwworld/class.hpp"
 #include "../mwworld/esmstore.hpp"
 
@@ -39,7 +41,7 @@ namespace MWMechanics
         int iPickMaxChance = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>()
                 .find("iPickMaxChance")->getInt();
 
-        int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+        int roll = OEngine::Misc::Rng::roll0to99();
         if (t < pcSneak / iPickMinChance)
         {
             return (roll > int(pcSneak / iPickMinChance));

apps/openmw/mwmechanics/repair.cpp

@@ -2,6 +2,8 @@
 
 #include <boost/format.hpp>
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwbase/world.hpp"
 #include "../mwbase/environment.hpp"
 #include "../mwbase/mechanicsmanager.hpp"
@@ -46,7 +48,7 @@ void Repair::repair(const MWWorld::Ptr &itemToRepair)
 
     float x = (0.1f * pcStrength + 0.1f * pcLuck + armorerSkill) * fatigueTerm;
 
-    int roll = static_cast<int>(static_cast<float> (std::rand()) / RAND_MAX * 100);
+    int roll = OEngine::Misc::Rng::roll0to99();
     if (roll <= x)
     {
         int y = static_cast<int>(fRepairAmountMult * toolQuality * roll);

apps/openmw/mwmechanics/security.cpp

@@ -1,5 +1,7 @@
 #include "security.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwworld/class.hpp"
 #include "../mwworld/containerstore.hpp"
 #include "../mwworld/esmstore.hpp"
@@ -48,8 +50,7 @@ namespace MWMechanics
         else
         {
             MWBase::Environment::get().getMechanicsManager()->objectOpened(mActor, lock);
-            int roll = static_cast<int>(static_cast<float> (std::rand()) / RAND_MAX * 100);
+            if (OEngine::Misc::Rng::roll0to99() <= x)
-            if (roll <= x)
             {
                 lock.getClass().unlock(lock);
                 resultMessage = "#{sLockSuccess}";
@@ -90,8 +91,7 @@ namespace MWMechanics
         else
         {
             MWBase::Environment::get().getMechanicsManager()->objectOpened(mActor, trap);
-            int roll = static_cast<int>(static_cast<float> (std::rand()) / RAND_MAX * 100);
+            if (OEngine::Misc::Rng::roll0to99() <= x)
-            if (roll <= x)
             {
                 trap.getCellRef().setTrap("");
 

apps/openmw/mwmechanics/spellcasting.cpp

@@ -4,6 +4,8 @@
 
 #include <boost/format.hpp>
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwbase/windowmanager.hpp"
 #include "../mwbase/soundmanager.hpp"
 #include "../mwbase/mechanicsmanager.hpp"
@@ -280,7 +282,7 @@ namespace MWMechanics
             if (castChance > 0)
                 x *= 50 / castChance;
 
-            float roll = static_cast<float>(std::rand()) / RAND_MAX * 100;
+            float roll = OEngine::Misc::Rng::rollClosedProbability() * 100;
             if (magicEffect->mData.mFlags & ESM::MagicEffect::NoMagnitude)
                 roll -= resistance;
 
@@ -383,8 +385,7 @@ namespace MWMechanics
                         target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::ResistCommonDisease).getMagnitude()
                       : target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::ResistBlightDisease).getMagnitude();
 
-            int roll = static_cast<int>(std::rand()/ (static_cast<double> (RAND_MAX) + 1) * 100); // [0, 99]
+            if (OEngine::Misc::Rng::roll0to99() <= x)
-            if (roll <= x)
             {
                 // Fully resisted, show message
                 if (target == MWBase::Environment::get().getWorld()->getPlayerPtr())
@@ -414,8 +415,7 @@ namespace MWMechanics
         if (spell && caster != target && target.getClass().isActor())
         {
             float absorb = target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::SpellAbsorption).getMagnitude();
-            int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+            absorbed = (OEngine::Misc::Rng::roll0to99() < absorb);
-            absorbed = (roll < absorb);
             if (absorbed)
             {
                 const ESM::Static* absorbStatic = MWBase::Environment::get().getWorld()->getStore().get<ESM::Static>().find ("VFX_Absorb");
@@ -463,8 +463,7 @@ namespace MWMechanics
                 if (!reflected && magnitudeMult > 0 && !caster.isEmpty() && caster != target && !(magicEffect->mData.mFlags & ESM::MagicEffect::Unreflectable))
                 {
                     float reflect = target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::Reflect).getMagnitude();
-                    int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+                    bool isReflected = (OEngine::Misc::Rng::roll0to99() < reflect);
-                    bool isReflected = (roll < reflect);
                     if (isReflected)
                     {
                         const ESM::Static* reflectStatic = MWBase::Environment::get().getWorld()->getStore().get<ESM::Static>().find ("VFX_Reflect");
@@ -492,7 +491,7 @@ namespace MWMechanics
 
             if (magnitudeMult > 0 && !absorbed)
             {
-                float random = std::rand() / static_cast<float>(RAND_MAX);
+                float random = OEngine::Misc::Rng::rollClosedProbability();
                 float magnitude = effectIt->mMagnMin + (effectIt->mMagnMax - effectIt->mMagnMin) * random;
                 magnitude *= magnitudeMult;
 
@@ -824,8 +823,7 @@ namespace MWMechanics
 
             // Check success
             float successChance = getSpellSuccessChance(spell, mCaster);
-            int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+            if (OEngine::Misc::Rng::roll0to99() >= successChance)
-            if (!fail && roll >= successChance)
             {
                 if (mCaster == MWBase::Environment::get().getWorld()->getPlayerPtr())
                     MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicSkillFail}");
@@ -903,7 +901,7 @@ namespace MWMechanics
                     + 0.1f * creatureStats.getAttribute (ESM::Attribute::Luck).getModified())
                     * creatureStats.getFatigueTerm();
 
-        int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 100); // [0, 99]
+        int roll = OEngine::Misc::Rng::roll0to99();
         if (roll > x)
         {
             // "X has no effect on you"

apps/openmw/mwmechanics/spells.cpp

@@ -38,7 +38,7 @@ namespace MWMechanics
                 for (unsigned int i=0; i<spell->mEffects.mList.size();++i)
                 {
                     if (spell->mEffects.mList[i].mMagnMin != spell->mEffects.mList[i].mMagnMax)
-                        random[i] = static_cast<float> (std::rand()) / RAND_MAX;
+                        random[i] = OEngine::Misc::Rng::rollClosedProbability();
                 }
             }
 

apps/openmw/mwrender/npcanimation.cpp

@@ -12,6 +12,8 @@
 
 #include <extern/shiny/Main/Factory.hpp>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/misc/resourcehelpers.hpp>
 
 #include "../mwworld/esmstore.hpp"
@@ -101,7 +103,7 @@ void HeadAnimationTime::setEnabled(bool enabled)
 
 void HeadAnimationTime::resetBlinkTimer()
 {
-    mBlinkTimer = -(2 + (std::rand() / static_cast<float>(RAND_MAX)) * 6);
+    mBlinkTimer = -(2.0f + OEngine::Misc::Rng::rollDice(6));
 }
 
 void HeadAnimationTime::update(float dt)

apps/openmw/mwrender/sky.cpp

@@ -19,6 +19,8 @@
 
 #include <boost/lexical_cast.hpp>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/nifogre/ogrenifloader.hpp>
 #include <components/misc/resourcehelpers.hpp>
 
@@ -464,8 +466,8 @@ void SkyManager::updateRain(float dt)
 
             // TODO: handle rain settings from Morrowind.ini
             const float rangeRandom = 100;
-            float xOffs = (std::rand()/(RAND_MAX+1.0f)) * rangeRandom - (rangeRandom/2);
+            float xOffs = OEngine::Misc::Rng::rollProbability() * rangeRandom - (rangeRandom / 2);
-            float yOffs = (std::rand()/(RAND_MAX+1.0f)) * rangeRandom - (rangeRandom/2);
+            float yOffs = OEngine::Misc::Rng::rollProbability() * rangeRandom - (rangeRandom / 2);
 
             // Create a separate node to control the offset, since a node with setInheritOrientation(false) will still
             // consider the orientation of the parent node for its position, just not for its orientation

apps/openmw/mwsound/soundmanagerimp.cpp

@@ -4,6 +4,8 @@
 #include <algorithm>
 #include <map>
 
+#include <openengine/misc/rng.hpp>
+
 #include "../mwbase/environment.hpp"
 #include "../mwbase/world.hpp"
 #include "../mwbase/statemanager.hpp"
@@ -224,7 +226,7 @@ namespace MWSound
         if(!filelist.size())
             return;
 
-        int i = rand()%filelist.size();
+        int i = OEngine::Misc::Rng::rollDice(filelist.size());
 
         // Don't play the same music track twice in a row
         if (filelist[i] == mLastPlayedMusic)
@@ -559,7 +561,7 @@ namespace MWSound
         if(!cell->isExterior() || sTimePassed < sTimeToNextEnvSound)
             return;
 
-        float a = std::rand() / static_cast<float>(RAND_MAX);
+        float a = OEngine::Misc::Rng::rollClosedProbability();
         // NOTE: We should use the "Minimum Time Between Environmental Sounds" and
         // "Maximum Time Between Environmental Sounds" fallback settings here.
         sTimeToNextEnvSound = 5.0f*a + 15.0f*(1.0f-a);
@@ -588,7 +590,7 @@ namespace MWSound
                 return;
         }
 
-        int r = (int)(rand()/((double)RAND_MAX+1) * total);
+        int r = OEngine::Misc::Rng::rollDice(total);
         int pos = 0;
 
         soundIter = regn->mSoundList.begin();

apps/openmw/mwworld/inventorystore.cpp

@@ -364,7 +364,7 @@ void MWWorld::InventoryStore::updateMagicEffects(const Ptr& actor)
                 // Roll some dice, one for each effect
                 params.resize(enchantment.mEffects.mList.size());
                 for (unsigned int i=0; i<params.size();++i)
-                    params[i].mRandom = static_cast<float> (std::rand()) / RAND_MAX;
+                    params[i].mRandom = OEngine::Misc::Rng::rollClosedProbability();
 
                 // Try resisting each effect
                 int i=0;

apps/openmw/mwworld/store.hpp

@@ -7,6 +7,8 @@
 #include <stdexcept>
 #include <sstream>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/esmwriter.hpp>
 
 #include <components/loadinglistener/loadinglistener.hpp>
@@ -178,7 +180,7 @@ namespace MWWorld
             std::vector<const T*> results;
             std::for_each(mShared.begin(), mShared.end(), GetRecords(id, &results));
             if(!results.empty())
-                return results[int(std::rand()/((double)RAND_MAX+1)*results.size())];
+                return results[OEngine::Misc::Rng::rollDice(results.size())];
             return NULL;
         }
 

apps/openmw/mwworld/weather.cpp

@@ -3,6 +3,8 @@
 
 #include "weather.hpp"
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/esm/weatherstate.hpp>
 
 #include "../mwbase/environment.hpp"
@@ -526,7 +528,7 @@ void WeatherManager::update(float duration, bool paused)
                 if (mThunderSoundDelay <= 0)
                 {
                     // pick a random sound
-                    int sound = rand() % 4;
+                    int sound = OEngine::Misc::Rng::rollDice(4);
                     std::string* soundName = NULL;
                     if (sound == 0) soundName = &mThunderSoundID0;
                     else if (sound == 1) soundName = &mThunderSoundID1;
@@ -542,7 +544,7 @@ void WeatherManager::update(float duration, bool paused)
                     mRendering->getSkyManager()->setLightningStrength( mThunderFlash / mThunderThreshold );
                 else
                 {
-                    mThunderChanceNeeded = static_cast<float>(rand() % 100);
+                    mThunderChanceNeeded = static_cast<float>(OEngine::Misc::Rng::rollDice(100));
                     mThunderChance = 0;
                     mRendering->getSkyManager()->setLightningStrength( 0.f );
                 }
@@ -624,7 +626,7 @@ std::string WeatherManager::nextWeather(const ESM::Region* region) const
      * 70% will be greater than 30 (in theory).
      */
 
-    int chance = (rand() % 100) + 1; // 1..100
+    int chance = OEngine::Misc::Rng::rollDice(100) + 1; // 1..100
     int sum = 0;
     unsigned int i = 0;
     for (; i < probability.size(); ++i)

apps/openmw/mwworld/worldimp.cpp

@@ -14,6 +14,8 @@
 #include <libs/openengine/bullet/trace.h>
 #include <libs/openengine/bullet/physic.hpp>
 
+#include <openengine/misc/rng.hpp>
+
 #include <components/bsa/bsa_archive.hpp>
 #include <components/files/collections.hpp>
 #include <components/compiler/locals.hpp>
@@ -3133,7 +3135,7 @@ namespace MWWorld
         const ESM::CreatureLevList* list = getStore().get<ESM::CreatureLevList>().find(creatureList);
 
         int iNumberCreatures = getStore().get<ESM::GameSetting>().find("iNumberCreatures")->getInt();
-        int numCreatures = static_cast<int>(1 + std::rand() / (static_cast<double> (RAND_MAX)+1) * iNumberCreatures); // [1, iNumberCreatures]
+        int numCreatures = 1 + OEngine::Misc::Rng::rollDice(iNumberCreatures); // [1, iNumberCreatures]
 
         for (int i=0; i<numCreatures; ++i)
         {
@@ -3184,7 +3186,7 @@ namespace MWWorld
 
         std::stringstream modelName;
         modelName << "Blood_Model_";
-        int roll = static_cast<int>(std::rand() / (static_cast<double> (RAND_MAX)+1) * 3); // [0, 2]
+        int roll = OEngine::Misc::Rng::rollDice(3); // [0, 2]
         modelName << roll;
         std::string model = "meshes\\" + getFallback()->getFallbackString(modelName.str());
 

components/CMakeLists.txt

@@ -160,7 +160,11 @@ include_directories(${BULLET_INCLUDE_DIRS} ${CMAKE_CURRENT_BINARY_DIR})
 
 add_library(components STATIC ${COMPONENT_FILES} ${MOC_SRCS} ${ESM_UI_HDR})
 
-target_link_libraries(components ${Boost_LIBRARIES} ${OGRE_LIBRARIES})
+target_link_libraries(components 
+    ${Boost_LIBRARIES} 
+    ${OGRE_LIBRARIES}
+    ${OENGINE_LIBRARY}    
+)
 
 if (GIT_CHECKOUT)
     add_dependencies (components git-version)

components/nifogre/particles.cpp

@@ -12,6 +12,8 @@
 #include <OgreSceneNode.h>
 #include <OgreSceneManager.h>
 
+#include <openengine/misc/rng.hpp>
+
 /* FIXME: "Nif" isn't really an appropriate emitter name. */
 class NifEmitter : public Ogre::ParticleEmitter
 {
@@ -171,7 +173,7 @@ public:
         Ogre::Real& timeToLive = particle->timeToLive;
 #endif
 
-        Ogre::Node* emitterBone = mEmitterBones.at((int)(::rand()/(RAND_MAX+1.0)*mEmitterBones.size()));
+        Ogre::Node* emitterBone = mEmitterBones.at(OEngine::Misc::Rng::rollDice(mEmitterBones.size()));
 
         position = xOff + yOff + zOff +
                  mParticleBone->_getDerivedOrientation().Inverse() * (emitterBone->_getDerivedPosition()

libs/openengine/CMakeLists.txt

@@ -23,7 +23,12 @@ set(OENGINE_BULLET
     bullet/trace.h
 )
 
-set(OENGINE_ALL ${OENGINE_OGRE} ${OENGINE_GUI} ${OENGINE_BULLET})
+set(OENGINE_MISC
+    misc/rng.cpp
+    misc/rng.hpp
+)
+
+set(OENGINE_ALL ${OENGINE_OGRE} ${OENGINE_GUI} ${OENGINE_BULLET} ${OENGINE_MISC})
 
 set(OENGINE_LIBRARY "oengine")
 set(OENGINE_LIBRARY ${OENGINE_LIBRARY} PARENT_SCOPE)

libs/openengine/misc/rng.cpp

@@ -0,0 +1,29 @@
+#include "rng.hpp"
+#include <cstdlib>
+#include <ctime>
+
+namespace OEngine {
+namespace Misc {
+
+    void Rng::init()
+    {
+        std::srand(static_cast<unsigned int>(std::time(NULL)));
+    }
+
+    float Rng::rollProbability()
+    {
+        return static_cast<float>(std::rand() / (static_cast<double>(RAND_MAX)+1.0));
+    }
+
+    float Rng::rollClosedProbability()
+    {
+        return static_cast<float>(std::rand() / static_cast<double>(RAND_MAX));
+    }
+
+    int Rng::rollDice(int max)
+    {
+        return static_cast<int>((std::rand() / (static_cast<double>(RAND_MAX)+1.0)) * (max));
+    }
+
+}
+}

libs/openengine/misc/rng.hpp

@@ -0,0 +1,36 @@
+#ifndef MISC_RNG_H
+#define MISC_RNG_H
+
+#include <cassert>
+
+namespace OEngine {
+namespace Misc
+{
+
+/*
+  Provides central implementation of the RNG logic
+*/
+class Rng
+{
+public:
+
+    /// seed the RNG
+    static void init();
+
+    /// return value in range [0.0f, 1.0f)  <- note open upper range.
+    static float rollProbability();
+  
+    /// return value in range [0.0f, 1.0f]  <- note closed upper range.
+    static float rollClosedProbability();
+
+    /// return value in range [0, max)  <- note open upper range.
+    static int rollDice(int max);
+
+    /// return value in range [0, 99]
+    static int roll0to99() { return rollDice(100); }
+};
+
+}
+}
+
+#endif

libs/openengine/ogre/selectionbuffer.cpp

@@ -10,6 +10,8 @@
 
 #include <stdexcept>
 
+#include <openengine/misc/rng.hpp>
+
 #include <extern/shiny/Main/Factory.hpp>
 
 namespace OEngine
@@ -145,7 +147,7 @@ namespace Render
 
     void SelectionBuffer::getNextColour ()
     {
-        Ogre::ARGB color = static_cast<Ogre::ARGB>((float(rand()) / float(RAND_MAX)) * std::numeric_limits<Ogre::uint32>::max());
+        Ogre::ARGB color = static_cast<Ogre::ARGB>(OEngine::Misc::Rng::rollClosedProbability() * std::numeric_limits<Ogre::uint32>::max());
 
         if (mCurrentColour.getAsARGB () == color)
         {