Pinch n Bulge

I was working on a project were we needed to make it look like something was going down a flexibe tube like an umbilical cord and while this could have been done using a spline warp or even a grid warp, it felt like the better way to do this was to just be able to paint a bit of a bulge. 

I remembered photoshop has a pucker and bloat tool so I went and looked at it. That's exactly what I wanted but couldn't find anything like it in Nuke.

Introducing Pinch n Bulge!

This gizmo either pushes pixels outward or pulls pixels inward based upon a provided mask. If a mask isn't provided it will use the alpha in the footage. It uses a matrix offset to push/pull pixels either away or toward the stroke. For best results when feeding it using a roto brush, use a hardness of 0. Though the soften knob will blur the incoming matte so that it's not such a hard push. This gizmo is similar to Photoshop's pucker and bloat tool when using liquify, but better because it's in Nuke!