Distortion Effects
Bending the image behind a surface
Also known as: Refraction effect · Heat haze · Shockwave distortion · Screen distortion · Distortion shader · Refraction VFX
Definition
Distortion effects bend or warp the image behind a surface, to create heat haze, shockwaves, energy fields, glass and water refraction. The shader samples the scene behind the object with its UV coordinates offset by a normal map or a noise texture, so the background seems pushed around. In Unreal Engine this is done through the refraction input of a translucent material, and in Unity by sampling the opaque texture, which must be enabled in the pipeline asset.
In production
Keep the distortion small and subtle, because strong values look like a glitch, and mask it with a soft shape so edges do not show. Animate the offset with a scrolling noise for a heat haze, or with an expanding ring for a shockwave. Distortion samples the screen, so it costs fill rate, and it cannot show things that are not already on the screen.
