This effect is like the liquefy filter in Photoshop. It lets the user smudge the camera texture by swiping their finger on the screen.
There are slider controls in the patch editor so you can easily adjust the parameters to fit your project.
Brush controls include size, hardness, and opacity. It makes smooth strokes even with fast movements, using an SDF line segment by Inigo Quilez. Brush Demo
Decay will slowly return the distortion back to normal.
And of course the distortion slider controls the strength of the distortion.
From Fabrice Neyret: https://www.shadertoy.com/view/sdjyRV
If you used this in client projects, or simply enjoyed making effects with my open-source projects, please consider a donation or sponsorship. One-time donations can be made with PayPal. Subscriptions can be through PayPal or Github Sponsors (click the heart sponsor button at the top of the page).