Support MaxNumberRipples setting (#7795)

CHANGELOG.md

@@ -174,6 +174,7 @@
     Feature #7698: Implement sAbsorb, sDamage, sDrain, sFortify and sRestore
     Feature #7709: Improve resolution selection in Launcher
     Feature #7792: Support Timescale Clouds
+    Feature #7795: Support MaxNumberRipples INI setting
     Task #5896: Do not use deprecated MyGUI properties
     Task #6624: Drop support for saves made prior to 0.45
     Task #7113: Move from std::atoi to std::from_char

apps/openmw/mwrender/ripplesimulation.cpp

@@ -80,6 +80,25 @@ namespace
 
         node->setStateSet(stateset);
     }
+
+    int findOldestParticleAlive(const osgParticle::ParticleSystem* partsys)
+    {
+        int oldest = -1;
+        float oldestAge = 0.f;
+        for (int i = 0; i < partsys->numParticles(); ++i)
+        {
+            const osgParticle::Particle* particle = partsys->getParticle(i);
+            if (!particle->isAlive())
+                continue;
+            const float age = particle->getAge();
+            if (oldest == -1 || age > oldestAge)
+            {
+                oldest = i;
+                oldestAge = age;
+            }
+        }
+        return oldest;
+    }
 }
 
 namespace MWRender
@@ -87,6 +106,7 @@ namespace MWRender
 
     RippleSimulation::RippleSimulation(osg::Group* parent, Resource::ResourceSystem* resourceSystem)
         : mParent(parent)
+        , mMaxNumberRipples(Fallback::Map::getInt("Water_MaxNumberRipples"))
     {
         mParticleSystem = new osgParticle::ParticleSystem;
 
@@ -159,9 +179,6 @@ namespace MWRender
 
                 currentPos.z() = mParticleNode->getPosition().z();
 
-                if (mParticleSystem->numParticles() - mParticleSystem->numDeadParticles() > 500)
-                    continue; // TODO: remove the oldest particle to make room?
-
                 emitRipple(currentPos);
             }
         }
@@ -226,7 +243,19 @@ namespace MWRender
             }
             else
             {
+                if (mMaxNumberRipples == 0)
+                    return;
+
                 osgParticle::ParticleSystem::ScopedWriteLock lock(*mParticleSystem->getReadWriteMutex());
+                if (mParticleSystem->numParticles() - mParticleSystem->numDeadParticles() > mMaxNumberRipples)
+                {
+                    // osgParticle::ParticleSystem design requires this to be O(N)
+                    // However, the number of particles we'll have to go through is not large
+                    // If the user makes the limit absurd and manages to actually hit it this could be a problem
+                    const int oldest = findOldestParticleAlive(mParticleSystem);
+                    if (oldest != -1)
+                        mParticleSystem->reuseParticle(oldest);
+                }
                 osgParticle::Particle* p = mParticleSystem->createParticle(nullptr);
                 p->setPosition(osg::Vec3f(pos.x(), pos.y(), 0.f));
                 p->setAngle(osg::Vec3f(0, 0, Misc::Rng::rollProbability() * osg::PI * 2 - osg::PI));

apps/openmw/mwrender/ripplesimulation.hpp

@@ -74,6 +74,8 @@ namespace MWRender
         std::vector<Emitter> mEmitters;
 
         Ripples* mRipples = nullptr;
+
+        int mMaxNumberRipples;
     };
 
 }