There are several different types of animated smoke effects you can create in After Effects, and several ways to create them. In this tutorial, I'm going to show you a quick way to simulate a dense campfire or chimney smoke using Particle Playground.
Let's get started!
First, make a new composition of 10 seconds or so, at whatever resolution you like - I'm working at 1280x720, as usual. Add a new black Solid (Command/Ctrl-Y), and make it the size of the comp. Apply Particle Playground to the comp (Effect > Simulation > Particle Playground) and set up Cannon as follows:
Note that I've moved the Cannon emitter to the bottom of the comp frame, and set Gravity to zero, so the particles won't fall back down after being emitted. Also note that I've set the Particle Color to a light grey. (These settings are just guidelines - experiment with them to create different types of smoke effect.)
Next, add a Gaussian Blur (Effect > Blur & Sharpen > Gaussian Blur) to the Particle Playground comp. Set Blurriness to 15, and Blur Dimensions to Horizontal and Vertical.
Next, we're going to add a mask to the Particle Playground layer that we'll use with the Wall feature to push the particles off to the side as they rise, so it looks like the smoke is being shifted by the wind.
Click on the Pen tool, and draw a simple 2-point mask directly in your Comp window to the right of the particle stream. Drag the handles of the mask to curve it slightly, and drag the top point so it lines up with the center of the Cannon stream. (Hit the Escape key after you draw the second point to make an open mask.) Your mask should look something like this:
Next, in Particle Playground, under Wall, set Boundary to the Mask you just drew. Leave the other settings at their defaults. This will make the particles bounce off the Wall as they rise, although you won't see much of that yet.
Next we're going to make a Property Map that will both increase the size of the particles and fade them out as they rise, for a more realistic smoke effect.
Add a new solid to your comp at the same size as the comp, and apply the Ramp effects to it (Effect > Generate > Ramp). Set up the Ramp as follows:
If you've made your comp at a different size, adjust the Start of Ramp and End of Ramp settings so that the Ramp is dark at the bottom center of the screen and light at the top center of the screen, as shown:
Next, pre-compose this comp (Layer > Pre-Compose...), choosing the option to Move All Attributes into the New Composition. Then, turn off the visibility of this layer as we don't need to see it.
For the final step, select the Particle Playground layer again, roll down the Persistent Property Mapper twirly arrow, and set Use Layer As Map to your Ramp pre-comp.
Next, under Affects, set Map Red to Scale, with Min/Max values of 0 and 25, respectively - this will make the particles get larger as they flow up the screen, and so make the smoke "clumpier" as it rises. Then set Map Green to Opacity, with Min/Max values of 1 and 0, respectively, as shown here:
Make sure that your Map Green Min is set to 1 and the Max to 0 (the opposite of the defaults) - this will make the smoke particles fade out as they approach the top of the frame.
Preview or render this out, and you should get something like this:
Note that the smoke doesn't look all that realistic at first, but once it gets going, it looks a lot like heavy fire smoke. If you're planning to use this effect for your own purposes, bear that in mind.
Of course, try adjusting all the various parameters in your composition, including the Gaussian Blur settings, the mask position, and Cannon's properties and see how the effect changes. Have fun!
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