A Guild to Beautiful Game

Adding a Particle System to simulate Fog in HDRP

Sometimes adding a simple effect can make a big difference to a scene especially when setting up the mood of the scene. This is especially true when adding smoke or fog into a dimly lit room such as the one we have created.

In this short article we will insert a fog particle system into our scene and watch it transform entirely from a basic dark room to something more interesting.

Adding the Particle System:

To start we will first need a 2D sprite/image of simple cloud or smoke, we need this as the material for the particle system since the particle system can use them as a material. I leave the sources on where to get those sprite drawings to you.

Once you have imported them into Unity, we will need to set the smoke texture as a 2D Texture shape with the Alpha Source set to “Input Texture Alpha” and also check on Alpha is Transparent.

Then we are going to create a new material for the smoke system. If you are using HDRP pipeline the Shader that we are going to use is called Alpha Blended, we can search for this within the text slot. This setting will ask for a particle texture which we will simply drag and drop our cloud/fog sprite.

Once that is done, it is time to add in our particle system. We are going to create a new empty object as the parent folder and then add in a particle system as a child object. We can do this by right clicking in the Hierarchy and under the Effects tab select particle system.

You will be greeted by a orb spawning object that is continuously generating particles. In the inspector within the particles component, if we scroll all the way down to the “Render tab” you will see a materials slot. We can drag and drop the newly created fog/cloud material here and you will see the changes happen immediately, of course not to our liking since it doesn’t look like fog.

This is where we can fine tune the particle system. To get the same fog setup as I have, you can follow my settings. I edited the Start speed, Start Size, and Start Color. I also turned on Emission and Shape.

Once you have find the settings which you are satisfied with we can see the final result really does affect the room mood, paired with the two box volume post processing, this room is really starting to look special.

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Simon Truong

Simon Truong

A Designer, an Illustrator and a massive tech geek aspiring to become a professional Unity Developer.