How I fix this problem ?
If the player stay near to the emitter, the scale of particles is the "real size", but if I get distance of the emitter, the size of particles grow/scale and I want to show the emitter always with the same scale (without worry about the distance of the player).
Hi, all the answers online did not help me, but finally I found the solution:
The thing is: Min Particle Size and May Particle Size Settings will not affect your particles as desired as long as “Billboard Alignment” is set to “view”!
So if you want that your partciles in Unity keep a constant, absolute size (= size of particle in the world, not relative to the camera or viewport), set Billboard Alignment to “Facing”.
Also check all the aother parameters shown in the following screenshot, because they may interfere with your particle size if configured the wrong way!
I showed it to a support guy at GDC who said this was a bug. Thanks for posting these pics, see below for mine.
The problem is that particles (each individual particle) is rendered at the same screen-size. So if you have good looking smoke coming off a cigarette close up, from a distance, it would look like a forest fire.
The culprit(s) seem to be that there is a 'max screen size' and you can hit it very easily by having particle sizes that either start out too big, or grow to be too big. If you are running into this problem, look at MaxParticleSize AND GrowSize, and reduce one or both. You may also want to check on Min and Max size on the emitter.
Now to prove that it's not simply 'set MaxParticleSize to 1', check these out. I used a large garrish texture so you can see that at near, mid, and far distances, the particles max out at the same on-screen size, even if MaxParticleSize IS 1. The white cube is 1 unit big, the gray plane is the default (10 units).
Setting that to, say, .1 helps quite a bit. It may depend on your scene, how far away you can see the P.S. as to whether you will notice this effect.