Particle Effects Tutorial

In this tutorial I will explain some methods for creating nice particles and a lot of things that are useful to know about the process. This will include extensive use of both Photoshop and Unity, so you will need both programs and at least some basic experience with them.

Just to warn you I am using Photoshop 7 so there might be some minor inconsistencies with later versions.

What you can create

Particle Effects Tutorial Chapter 1: Simple Smoke
Chapter 1 Step 1: Clouds is your friend
Pretty much any particle you make will use the clouds or difference clouds filter at least once. Clouds will create a randomized fractal image based on the foreground and background colors. Create a new image that is 128 pixels by 128 pixels, make sure the foreground color is black and the background color is white, then do the filter Menu: Filters > Render > Clouds. You will get a randomized fractal image that looks somewhat like this:


Clouds

We now have the color of the smoke laid out. However smoke is transparent so we need to build an alpha channel. The alpha channel defines the shape and transparency of the smoke. To start building the alpha channel, create a new layer for it, then add a gradient circle to this layer. To add a gradient circle, set the foreground color to white and the background color to black, select the gradient tool, set the gradient mode in the top bar to Radial Gradient and set the gradient to Foreground to Background in the gradient picker. Now click in the center of the image and drag to an edge, but let go a little bit before actually reaching the edge.


The gradient settings, and thefirst step for an alpha channel

Our alpha channel is pretty boring right now. It needs some shape. How we will add shape is by creating new clouds and blending them over the circle. However, the clouds that you get when generating them at 128x128 are too big compared to the size of the smoke to be details. So create a new image that is bigger, like 400 by 400 pixels and create clouds in it, then scale it back down to 128 by 128. Since this layer is only meant to create an interesting shape we will use contrast adjustments and blurring to get a nicer softer effect. Give it some more contrast with Menu: Image >Adjustments >Brightness and Contrast... Set the Contrast slider to 50, then hit (OK). Now blur it some with Menu: Filters > Blur > Gaussian Blur... Set the blur radius to somewhere around 8 pixels and hit (OK). Copy the pixels from that image and paste them into the other image that has the gradient circle. If the new layer created by pasting isn't on top of the stack of layers, move it up. Then set it's blend mode to Multiply. To do this, select the new layer and click on the drop down in the Layers tab that says "Normal" and choose Multiply from the menu.


The blurred clouds add shape

Now we will add a little sharp detail to the smoke. Create a new layer and if it isn't on top move it up, then create clouds in it. Set it's blend mode like you did for the previous layer, but set it to Overlay this time. You can adjust how much this layer effects the image with Menu: Image > Adjustments > Brightness and Contrast... Drag the Contrast slider back and forth until you get something you like.


The alpha with sharp details

We have our alpha channel done now, and stored in separate layers so if we want to change it later we can. But we need it all on one layer for the actual new channel. So merge the top three layers down by selecting one of the top three, hiding the lower color layer by clicking on the eyeball icon that is next to it in the Layers tab and pressing [Command] + [Shift] + E or Menu: Layer > Merge Visible. Once it is merged select all and copy, then go back to before you merged the layers by clicking on the entry before Merge Visible in the History tab and paste on a new layer. Now select the Channels tab by clicking on it (It should be next to the Layers tab.) Create a new channel by clicking on the new channel button at the bottom of the tab and paste your alpha channel into it. Click on the eyeball icon next to the top channel named RGB to show it, but make sure the alpha channel is still selected. Without clicking on anything else in the channels tab, go back to the layers tab and hide all of the layers except for the bottom one.



The eyeball icon

You are now done! Save the file to a relevant place as a PSD, possibly
your Unity project Assets folder.


Our finished smoke. The red is the alpha channel

Chapter 1 Step 2: Importing your file into Unity

Open Unity into your current project or create a new project for this tutorial. If your particle texture isn't already in your Assets folder, move it there. You should be able to find the texture in Unity's Project pane. Once you find it, select it and look at it's properties in the Inspector. Click on the "Show Alpha" checkbox to check if the alpha channel made it into Unity. If instead of your alpha channel you see a full white image, continue on and we will fix this problem. Otherwise jump to step 3 and we will create a simple smoke particle system.


The texture in Unity's Inspector

The easiest way I have found to fix this mistake is just start all over in a new image. Open the image that isn't importing the alpha. If there are multiple layers for the particle color, merge all the color layers together with [Command] + [Shift] + E. Then copy all the pixels, create a new image and paste the pixels in with [Command] + V. Go back to the old image and open the channels tab, select the Alpha 1 channel and copy it. Go to the new image, open the channels tab, create a new channel and paste the alpha you copied into it. Now without deselecting your new channel click on the box where the eyeball should be on the top RGB channel to show it.

Without touching anything else, save the file into your Assets folder with a new name.

Chapter 1 Step 3: Get your particle texture onto a particle system

Create a new particle system, in the Menu: GameObject > Create Other > Particle System. Then drag your particle texture from the Project pane to the particle system in the Hierarchy pane or Scene View pane. This will automatically generate a material for the particle. Select the particle system and scroll down to the bottom of the inspector where the material is. In the material component select a shader from the shader menu: Particles > Alpha Blended. Alpha blended is a great blend mode for smoke, water splashes, dust, debris, or anything that is dark in color or doesn't emit light.

Now scroll up to the top of the Inspector where the Particle Emitter component is. Set the Min Size and Max Size values to 1. Now your particle system should look somewhat like this:


The particle material and the particle system with the material applied

You can change the color and transparency of the smoke by fiddling with the Tint Color of the material. Light white steam or thick black toxic smoke, it is up to you.

Chapter 1 Step 4: Smoke gracefully rising into the air

For our smoke to look like real smoke coming off a fire or something we should change several of the particle system variables. I will walk you through it, as I would do it, step by step.

1. The stuff needs to travel upwards. Set the Particle Emitter's World Velocity to (0, 1.5, 0).
2. It needs to expand as it moves upwards. Set the Particle Animator's Size Grow to 0.4.
3. It should live longer, and a large range in lifetimes often looks good. Set the Particle Emitter's Min Energy to 1 and Max Energy to 8.
4. The area in which the particles appear is too big. Set the Particle Emitter's Ellipsoid to (0.25, 0.25, 0.25).
5. The smoke travels too straight. It needs some random velocity. Set the Particle Emitter's RndVelocity to (0.3, 0.3, 0.3)
6. The particles are too big. Set the Particle Emitter's Min Size to 0.5 and Max Size to 0.6.The Particle Animator's default color animation fade is alright but we can have a better one.
7. Set Color Animation[1] to have full opacity, Color Animation[2] to have 75% opacity and Color Animation[3] to have 25% opacity.
8. It needs more particles. Set the Particle Emitter's Min Emission to 70 and Max Emission to 90.
9. You can play with the colors and settings any way you want. Try different tints on the material and Color Animation. I usually leave the particle mostly unsaturated except for the parts of the particle that should be a different color, have the general color of the particle stored in the material color and have time specific things like fades in the Color Animation.
   

Here is what I came up with:


My smoke

Make sure to store your effect safely in a prefab or save the scene.

Particle Effects Tutorial Chapter 2: Advanced smoke

Chapter 2 Step 1: Fake lighting

Right now our particle has no lighting. It is just one flat color. This is mostly ok, but it will look a little better with some faked lighting baked into the colors.

You can get pretty good results for lighting just by overlaying a gradient with white at the top and black at the bottom. To do this create a new layer for your gradient above the first layer but below the alpha channel layers. Set your foreground color to black and background color to white by pressing D or clicking on the default foreground and background colors icon next to the colors in the tool palette.

Now select the gradient tool and set your gradient style to Linear Gradient and gradient to
Foreground to Background. Click and drag the gradient from the bottom of the image to the top with your new blank layer selected. Then set the blending mode of your new layer to overlay.

It should look something like this:


Smoke with fake lighting

Chapter 2 Step 2: Particle Animation (the Wave filter is also your friend)

Particle animation in Unity is achieved by creating a single image that holds all of the frames and letting the Particle Renderer move the particle's UVs around to match up with each "frame". Particle animation can really bring a particle system to life but requires a bigger image and a lot more time spent creating the particle. The best method I have found for animating particles is to use a careful routine with the Wave filter that lets you choose a target state to morph to and then move to that state slowly over a few frames. I will give you step by step instructions for this procedure as well as guide you through creating the animation.

Your animation will need to be in a separate, larger file. Create a new image that is four times as wide and four times as tall as your current particle. This will hold 16 frames, which is generally enough for animated smoke. In my case that would be
512 by 512 because my particle is 128 by 128.

We will now start the animation procedure. Go back to your particle, select the lowest difference clouds layer and do the wave filter. Menu: Filter > Distort > Wave. There are a lot of settings to tweak here. Try different things until you get a distortion that you like. If you can, try to make it work with a Amplitude Min of one and a Amplitude Max of 16 (The number of frames. This makes animation easier). Then hit the Randomize button until you get a shape that you like. My settings are:

Type: Sine (always use Sine)
Number of generators: 15
Wavelength min = 10, max = 50
Amplitude min = 1, max = 16
Undefined Areas: Wrap Around



Wave filter dialog

The result of this filter with these settings will be our particle at the end of the animation.
To increment our Wave for each frame we will start with Amplitude Max at 1 and then add one to it every time. Now hit the Ok button and then hit Command Z. (We could hit the Cancel button, but then our settings wouldn't be saved).

Repeat these steps for each frame:

1. Select the original particle image and go back to the original time before any Wave filters happened in the History tab.
2. Apply the wave filter to both the difference clouds layer and the alpha channel layer (You should have both of these available as a single layer in your original particle image). Set the Amplitude Max to a value that is equal to the value of the original Amplitude Max you chose divided by the number of frames, times the current frame index. (original Amplitude Max / number of frames) * current frame index. If you chose a number for your original Amplitude Max that is equal to the number of frames like I did, just add one to Amplitude Max every time. This will make your Amplitude Max the same as the frame index.
3. Copy both the difference clouds layer and alpha channel to new layers in the animation image and position them in the next available space. It goes from left to right in rows like English text. Here is a grid with all the frame indexes laid out:

01 02 03 04
05 06 07 08
09 10 11 12
13 14 15 16

How the animation is built

Repeat until you have filled the animation image with frames. It helps to make sure the layer order in your animation image stays organized so it easier to merge all of the alpha layers and color layers when you are done.

Once you have finished, merge all of the difference clouds layers into one layer and merge all the alpha channel layers into one layer. Then copy the lighting gradient overlay from the old particle to the new animated one and copy it onto each square, and merge it into one layer and set it's blend mode to Overlay.

Your alpha channel probably has some sharp edges in between frames. These will show up on the edges of your particles in Unity if you don't get rid of them. What I do about this is get a largish soft brush and paint straight lines in black along the edges of the image and the edges of the frames.

Note: Hold down the shift key while painting to paint in straight lines.

Once you have fixed that, copy the contents of your alpha channel layer, then hide it. Then go to the channels tab, create a new channel and paste your alpha into it, show the rgb channel again and Save your image into the Assets folder.

Chapter 2 Step 3: Use your animated texture in Unity

The Unity side of particle animation is easy. Select the particle material (either in the particle emitter or project pane) and drag the animated texture from the project pane into it's texture slot. Then just select your particle system, go to the Particle Renderer component in the inspector and set the "UV Animation" values.


The UV Animation variables

For this case, X Tile = 4, Y Tile = 4, Cycles = 1. Set those and you are done!

Note: You will notice an improvement in rendering quality if you set the Particle Renderer's Stretch Particle variable to Sorted Billboard. This will slow down rendering a little bit but it is a small price to pay for the benefit. Especially on lit smoke particles. With additive and other blend modes it doesn't effect anything.

Particle Effects Tutorial Chapter 3: Fire

Chapter 3 Step 1: Make a flame particle

Making a flame particle is harder. It needs to have colors, an alpha channel, and convincing flamelike appearance .To start out, make a new file that is 128 by 128 pixels. Set the foreground and background colors to black and white, then do Clouds. We will want our clouds to have more contrast in a few steps, so do an auto levels with [Command] + [Shift] + L. Now our flame needs some color. Press [Command] + B to bring up the color balance window. Make sure the Preserve Luminosity is off, then select the Shadows radio button and drag the top slider all the way to the right (make it red), select the Midtones radio button and do the same, then select the Highlights radio button and drag the top slider over to the right, the bottom slider all the way to the left and the middle slider about halfway to the right. The result should look sort of like this:


Proto flame

Now we will give this fire some black borders and a highlight in the middle using the Lighting Effects filter.
Menu:Filters>Render>Lighting Effects.

Note: Entering values into the numeric fields of this filter seems broken in my version of photoshop. Just drag the sliders until you are close to the target value. Also notice how the picture shows the light a considerable bit smaller than the image. This is important for the next few steps to work out right.


Lighting Effects preview

You can experiment and try to get it to look like what I have in the picture or use my settings. They are:

Drag the light handles around until your spotlight is a circle like in the picture.
Color: white
Intensity: 32
Focus: 5
Gloss: -100 (Matte)
Material doesn't appear to matter at all.
Exposure: 0 (Halfway point)
Ambience: 0 (Halfway point)
Texture channel: None

Once you have your Lighting Effects done, make about three copies of the layer. Then apply the Wave function a few times to each one to give it some shape. Try to get interesting flame shapes. It takes some time to get used to using the wave filter to create a specific effect. Keep in mind that it usually takes about three wave filters before it looks good and flamelike. If you want you can use the settings I used and just press the randomize button until you get something you like. Here are my settings:

Number of Generators: 5
Wavelength: Min = 10, Max = 50
Amplitude: Min = 5, Max = 25

Here is an example of the progression of one of your three layers:


Progression using Wave

Once you are done with distorting the three images, get a soft brush about 50 pixel size and paint black on any part of the fire on each layer that sticks out to the edge, or any part you don't like. Create a new layer at the bottom of the stack and paintbucket it black, set the top three flame layers' blend modes to Screen, set their layer transparencies to about 60% and then merge all of the layers together. You probably want to smooth out the flames a bit. To do this, copy your one layer and then blur whichever layer is on the bottom by about 4 pixels with Menu: > Filters > Blur > Gaussian Blur... Finally, set the top layer's blend mode to Screen and merge.

Here is what mine looks like at this point:


The flame is getting better

If we were to use this as it is as a particle in Unity it would look horrible. But before we adjust the colors and make an alpha channel, we need to animate it. This way we only have to animate one layer.

Do the animation just like you did for the smoke, but with 8 frames. I recommend a configuration with two lines of four frames. That would make the new animation image 512 by 256 pixels. You might want to use two separate Wave fades to get a better looking animation with more action. To do this, just pretend that you are making two separate animations, except the starting image for the second is the last frame of the first and the first animation takes up the first line while the second takes up the bottom line. When making the transition from line one to line to two, instead of going back to before you did the wave filter in the history tab, do another wave where you press the Randomize button to set a new target. Then hit the (OK) button, undo and then go from Amplitude Max at one to whatever it is in your target again, putting frames in the lower row.

Before you merge all of the layers, blur the later frames a bit. Starting at the last frame, blur with Menu: Filters > Blur > Gaussian Blur... set at 10 pixels. Then work back through the layers blurring them, but decrease the radius by two pixels each frame.

Note: This might cause ugly white borders near the blurred layers. To fix this, paintbucket the background layer black.


The flame animated

Once you are done with the animation and have blurred the later frames and merged all of the frames into one layer, you can start working on the colors and alpha. But first, paint black on all the edges with a large soft brush to avoid sharp edges. To make the alpha channel layer, copy your layer and desaturate it with [Command] + [Shift] + D, then hide it. To make the color layer, first create a new layer below all the others and paintbucket it a dark red-orange color. The color I used is #702105. Set the original animated layer's blend mode to Screen.

It is getting better but still needs adjustment. First, darken the layer by about 40% with Hue/Saturation/Brightness (Command U). Then, do a color balance like we did at first but less intense. Press [Command] + B to bring up the color balance window. Make sure the Preserve Luminosity checkbox is off, then select the Shadows radio button and drag the top slider to the right 75%, select the Midtones radio button and do the same, then select the Highlights radio button and drag the top slider to the right 75%, the bottom slider to the left 75% and the middle slider a little less than halfway to the right.

Copy the contents of your alpha channel layer, then hide it. Then go to the channels tab, create a new channel and paste your alpha into it, show the rgb channel again and save your image into the Assets folder. You are done!


The flame color and alpha

Chapter 3 Step 2: Flame emitter

Once you have your flame particle finished you will want to test it out in Unity.
Do it like before, create a new particle system and drag the texture onto it. You will want to set the material's shader to Particles>Additive and the Particle Renderer's UV animation variables. I will let you do more of the tweaking this time, just give some guidelines. If you don't know where some variable is in the particle system or wonder what a variable does, look it up in Chapter 5.

First, the particles have to be big enough for flames. Somewhere around 1.
Fire has a shorter lifetime. Somewhere around 1 again.
It should move upwards and have some random movement.
It should shrink in size, but not too much. To make it shrink,
set the Particle Animator's size grow value negative in between zero and negative one.
The ellipsoid should be a lot smaller.

As it fades out, try adding some red in the color animation. Also, it should fade in faster and fade out slower Make sure you have enough particles. Some variation in the min and max emission values is good for fire. More velocity and a lower damping value can help. Don't be afraid to try different things with the material color. I found that the fire was too bright normally.

I recommend using a black background color for looking at fires. If you don't like how the fire looks against whatever it is going to be put against, try giving it two materials in the Particle Renderer. The first one (Background) should be alpha blended and darker with a little less opacity, and the second one is the normal Additive one. Both should use the same texture. If you are looking at your fire in the game view with the standard blue color you will really be able to notice the difference between plain additive and additive + blended.

Here is mine:


The flame particle system

You don't have to try to emulate exactly that, but it shows one way to do it. Be original!

Make sure to store your effect safely in a prefab or save the scene when you are done.

Particle Effects Tutorial Chapter 4: Mix it up

Chapter 4 Step 1: Fire and smoke

If you want you could try combining your fire and smoke effects. Start by creating a new game object with Menu: GameObject >Create Empty or [Command] + [Shift] + N. Name your new object "Fire Group". Now select both the fire emitter and smoke emitter and press Command D to duplicate them. Drag your duplicates on the "Fire Group" object in the hierarchy. This will make them children of it so that they are grouped with it. Now select both the fire and smoke children in turn and type zeros into their position values. This will make them centered on their parent. Now just position the smoke above the fire a bit and then tweak values on both particle systems until it looks good. Here are some adjustments that help:

The ellipsoid on the smoke needs to be bigger.
The smoke particles should start out bigger and grow in size less.
The smoke should fade in slower, and have some orange color in the beginning.
The fire particles should live longer.
The smoke particles should have the same upwards velocity as the fire particles.

Try things until it looks good.


Fire and smoke

You may notice some flickering in between the fire and smoke. This is caused by close proximity of the two effects.

Unity renders particle systems in a layer like manner. It decides which system is on a higher layer by comparing the distances to the camera from the center of each system's bounding box. What we want is the flames to always be on top. To archive this you can use a script that moves the system a little bit closer to the camera. Here is the script I use:

ParticleLayer.js

To get the script into the project, click on the Create menu in the Project pane and select JavaScript from the menu. Name your script "ParticleLayer" and then open it and paste the code into it. Save it, return to Unity and wait for it to compile. (Shown by a little rotating thing in the lower right corner. With just this script it should be almost instant) Once it is done, drag the script from the Project pane to the Hierarchy and onto your fire particle emitter that is a child of "Fire Group". Then select the object you just dragged the script onto and set Layer Height to 0.5. This will make the fire always 0.5 meters closer to the camera then it normally would be.

Chapter 4 Step 2: A simple rocket

Lets try making a rocket with our fire and smoke. Create a new game object and name it "Rocket", then copy the fire and smoke into it as children like we did before. Now create a cube and scale it so that it is 0.6 meters long and generally rocket shaped. Drag it onto the "Rocket" object to make it a child and then make sure it is at the same position as it's parent. Move the child flames back to the back of the box and the child smoke about 3 meters behind the flames.

Now as you can guess you need to change the particle systems. But first, lets watch the rocket move so we can see what is wrong with it. I have made a moving rocket script for you to use. Get the script into the project, wait for it to compile and drag the script from the Project pane onto the Rocket object in the Hierarchy. Select the Rocket and set its Speed variable to 60, then run the simulation. As you can see there is a problem with the particles.


The particles are too far apart

Rocket.js

Note: You don't need the dual material setup for the fire on a rocket. You should make a new material for the rocket that is additive with a lighter yellow color and just use that one.

What we need to do is make more particles and make them very short lived.
Getting rid of the large ellipsoids and world up velocity would help too.
Just to give a sense of the scale here, I used 400 to 600 for the emission of the flames and 0.1 to 0.2 for the lifetime (called energy in the Particle Emitter). For the smoke, I use 300 for the emission and a lifetime of 0.1 to 5.
Also, increase the original sizes by a lot and decrease the Size Grow.
Try messing with random velocities, size grow and color fades on both emitters until you get something you like when you run the game.
Another thing that adds a little spice is a backwards velocity and damping on the smoke to simulate it being thrown out of the rocket.

Refer to Chapter 5 if you are confused about the functionality of any part of the particle system.

Here is my rocket. There are many ways to make rockets and this is just one of them.


A much improved rocket

Chapter 4 Step 3: A simple explosion

Now our rocket needs an explosion. Create a new game object and name it "Explosion", then copy the fire and smoke from the Rocket into it as children. First, set One Shot to true on both emitters. Now they will emit all at once like you want for an explosion. What to do next is think about how explosions work. Since the rocket is impacting a surface and then exploding, the explosion will force hot gasses away from the surface. I have my rocket script set up to make the explosion's forward axis face away from the surface that the rocket hit, so that you can easily achieve the effect I just mentioned. Just add to the Z component of Local Velocity.

Once you have done that, you should adjust how the particles look. Some starting points:

Decrease the number of particles. Anywhere from 60 to 150 should be enough for each emitter.
Increase the particle size by a lot.
The flames need a longer lifetime, the smoke needs a slightly shorter lifetime
Both systems need lots of random velocity and damping.
Your flame system probably still has a Particle Layer component. Good! Since this is probably a bigger effect overall, increase the layer height.


The explosion

You are probably getting used to manipulating particles at least a little bit by now, so I trust you to make it look cool without muchdirecting. Once you are done with that, you should get this script into your project and put it on your "Explosion" object.

Explosion.js

As soon as you have this script on the explosion you should be able to see it work right in action when you press play. Tweak it some more until you are satisfied. Refer to Chapter 5 if you are confused about the functionality of any part of the particle system.

To make an explosion be created when the rocket hits something, create a new prefab with the Project pane Create menu, name it "Explosion" and drag the explosion object in the Hierarchy pane onto your new Prefab. Then select the rocket object in the scene and drag your explosion prefab onto it's Explosion variable. Finally, put a big cube in front of the rocket for it to run in to.


Rocket hits the box

Congratulations on completing this tutorial! Have fun making (and watching) your cool new fireworks!


Particle Effects Tutorial Chapter 5: Detailed info on every variable in the particle system

For a reference I will go through every variable in the particle system from top to bottom and explain exactly what it does.

Particle Emitter Component:

Emit	On or off. Self described.
Min Size - Max Size	The size of new particles will be random in between these values. A lot of variation here like 0.1 and 10 probably won't look good.
Min Energy - Max Energy	Incorrectly named, the lifetime of the particles. New particles will last a random amount of seconds in between these values. Don't be afraid to set Min Energy close to zero.
Min Emission - Max Emission	How many particles are emitted every second if One Shot is false, or how many particles in a shot if One Shot is true.
World Velocity	A Vector3 representing how much velocity to add to the particles as they they spawn, in worldspace. (0, 10, 0) will make the particles fly up at 10 meters per second.
Local Velocity	A Vector3 representing how much velocity to add to the particles as they they spawn, in local space. (0, 0, -10) will make the particles shoot out the rear of the particle system at 10 meters per second.
Rnd Velocity	A Vector3 representing how much randomization to add to the velocity of each particle. It is in local space. (2, 0, 0) will make the particles shoot out both sides of the particle system at in between 0 and 2 meters per second.
Emitter Velocity Scale	How much of the emitter's velocity to add to the particles. Negative will make them shoot backwards like the exhaust of a rocket and positive will make them inherit velocity from the particle system.
Tangent Velocity	Tangent velocity only works for ellipsoid particle emitters. It's most useful when you want particles to move directly away from the centre of the emitter (Z greater than 0) or directly towards the centre (Z smaller than 0)
Simulate in World Space?	When you move the particle system do the particles move with it? Or do they stay in the same place in world space like a trail of smoke behind a moving object?
One Shot	Emit all the particles at once or constantly? True for explosions, false for smoke trails. Usually if it is One Shot you want it to disappear after it is done. To do this put a script with particleEmitter.emit = false; Destroy(gameObject, particleEmitter.maxEnergy); on your emitter object.
Ellipsoid	The size of the circular area in which to emit particles. In local space.
Min Emitter Range	Never emit particles closer than this to the center.

Particle Animator Component:

Does Animate Color?	Color Animation lets you make the particles change color over their lifetime. This is almost always essential because of the need to fade out particles. Try different transparency curves and color changes with your particle systems to see what looks best. If for some reason you don't need this, turn it off and save CPU cycles.
Color Animation[0 to 4]	Colors for the color animation.
World Rotation Axis	This vector3 axis controls the particle system rotation in worldspace. This is used for things like cyclones where you want the particles to spin around. This does not rotate the particles relative to the camera. Instead, it spins them around an axis. It depends on already existing velocity and can get out of control in an ugly way.
Local Rotation Axis	Same as above, just in local space.
Size Grow	How much to grow the particles every second. It appears to be multiplicative. The longer-lived your particles are the smaller this should be. It can also make particles smaller over time when negative.
Rnd Force	Random Force causes particles to jitter. It moves them back and forth sometimes and sometimes just in one direction more or less. This is a vector3 in world or local space depending on the Particle Emitter's Simulate in World Space? Variable.
Force	Adds a force on all particles and will add to their velocity every second. Use this to simulate gravity or wind. This is a vector3 in world or local space depending on the Particle Emitter's Simulate in World Space? Variable.
Damping	Multiply the particle's velocity by this every second. The lower, the more "drag" the particles have. If it is 1 there will be no effect on the particle's motion. Nice violent effects can be made by having a lot of initial velocity and also a lot of drag.
Autodestruct	If this is true and there are no particles in the system the Particle Animator component will destroy its parent Game Object. This will not make it disappear after all the particles run out from a one shot emission. It will simply fire all the particles again.

Particle Renderer Component:

Materials	Almost always just one material here but many can be used. The higher the index the higher the layer. If you do use many materials make sure that you strike a good balance. I tested this out with a very dark particle on bottom and a bright additive on top to make a decent explosion effect. Not quite as good as multiple emitters but probably can save CPU cycles.
Camera Velocity Scale	If you use stretched particles they will stretch with camera motion this amount. I have never used this.
Stretch Particles	Choose between Billboard (probably fastest, use for billboard style additive particles like flames or for particles you want to be faster), Sorted Billboard (Slower, use for smoke effects where depth matters), and Stretched (probably slowest, use for things like lasers, sparks, rain, etc anything with long particles).
Length Scale	Base length for stretched particles. Doesn't do anything if Stretch Particles isn't set to Stretched.
Velocity Scale	How much more to add to the length of stretched particles depending on their speed.
Max Particle Size	Don't ever let particles be drawn bigger than this. I think the default value 0.25 means "A quarter of the screen". This can cause ugliness when inside particle effects but saves a lot of performance at the same time. Generally just a safeguard against fill rate monster effects. You should never need this if you are careful.
UV Animation	This is where you control particle animations. It contains three variables, X Tile, Y Tile and Cycles. If you have an animation with 16 tiles laid out on a 4 by 4 grid both X Tile and Y Tile should be 4. If you have an animation with 8 frames from left to right X Tile should be 8 and Y Tile should be 1. As far as I can tell Cycles is very broken and should always be one. If it worked you presumably could have a looping animation.