Emitter does not like being paused

[Auria]

In SuperTuxKart, we have an emitter attached to each kart to produce nitro. When the user is not using nitro, we 'pause' the emitter by calling

Code: Select all

    m_emitter->setMinParticlesPerSecond(0);
    m_emitter->setMaxParticlesPerSecond(0);

and later when we need it again, we make similar calls, but wit non-zero values.

However, there is a bug when doing this : if the particle emitter was paused during 10 seconds, when you resume it, it suddenly fires 10 seconds' worth of particles all at once, producing a dense cloud of particles. (This is because the current implementation tracks the elapsed time between two calls to "emitt", but "emitt" does not seem to be called when the emitter is paused.

Find below a patch that corrects this issue :

Code: Select all

Index: Irrlicht/CParticleBoxEmitter.h
===================================================================
--- Irrlicht/CParticleBoxEmitter.h	(revision 3516)
+++ Irrlicht/CParticleBoxEmitter.h	(working copy)
@@ -42,11 +42,26 @@
 	virtual void setDirection( const core::vector3df& newDirection ) { Direction = newDirection; }
 
 	//! Set minimum number of particles emitted per second.
-	virtual void setMinParticlesPerSecond( u32 minPPS ) { MinParticlesPerSecond = minPPS; }
+	virtual void setMinParticlesPerSecond( u32 minPPS )
+    {
+        MinParticlesPerSecond = minPPS;
+        
+        // if 0, "emitt" will no longer be called, so stop counting time since last call
+        if (minPPS == 0)
+            Time = 0;
+    }
 
 	//! Set maximum number of particles emitted per second.
-	virtual void setMaxParticlesPerSecond( u32 maxPPS ) { MaxParticlesPerSecond = maxPPS; }
+	virtual void setMaxParticlesPerSecond( u32 maxPPS )
+    {
+        MaxParticlesPerSecond = maxPPS;
+        
+        // if 0, "emitt" will no longer be called, so stop counting time since last call
+        if (maxPPS == 0)
+            Time = 0;
 
+    }
+
 	//! Set minimum start color.
 	virtual void setMinStartColor( const video::SColor& color ) { MinStartColor = color; }
 

[CuteAlien]

Shouldn't the emitter still run when only setMinParticlesPerSecond is set to 0?

[hybrid]

Why not use the clearAllParticles() method which kind of restarts the particle system? It's a new method introduced a few weeks ago, IIRC exactly to cope with this situation.

[Auria]

Why not use the clearAllParticles() method which kind of restarts the particle system? It's a new method introduced a few weeks ago, IIRC exactly to cope with this situation.

Interesting, didn't know about it.
Sadly we're still on 1.7.2 so I cannot modify the code to use this solution until a new release with this method is out

[sudi]

@Auria
i actually pause my particle system by calling setEmitter(0) and then when activating it setting it back to my emitter. works pretty good.