Using Cookies To Create Realistic Lighting In Unity
Cookies (not the edible or browser kind) allow textures to be overlayed over lights in the Unity scene, to create useful visuals.
Cookies in Unity and Game Development:
Cookie is a term used for a few different meanings, but today I’m talking in the context of game development and environment design. In this context, it generally means a texture applied to a light source to control the shape of the light emitted, and often make it more realistic.
A cookie of this type often looks something like this:
This texture could be applied to a flashlight, and the light projected onto any surface aimed at would look like this. The black areas are where 0% of light is emitted, and the white are where 100% of light is emitted. Light cookies are always greyscale/black-&-white, because they have no need to be anything else since only alpha is important.
Adding a Cookie to a spotlight:
The option for cookies can be found on the Light component under Emission, and accepts a texture file.
NOTE: HDRP does not accept the “Cookie” Texture Type for some reason, differing from other render pipelines, so when in HDRP you must use the “Default” Texture Type.
For a Spotlight, the Texture Shape will be 2D.
You will also need to enable Alpha Is Transparency, and if the Cookie texture has a black background (as opposed to transparent) you’ll need to set the Alpha Source to “From Gray Scale”.
Remember to click “Apply”.
Adding a Cookie to a Point Light:
Yes, Cookies can also be applied to Point Lights to control the light emission in 360 degrees.
Cookies on Point Lights can be used in situations such as for wall-mounted lights/sconces and candles shining in 360 degrees.
To function for Point Lights, the Cookie texture must be a “Cube” map instead of simply “2D”. You will also need to choose a Mapping option, but “Mirrored Ball (Spheremap)” is a good default.