Vertex based screen deformation fx

A keynote on Unite 11 mentioned a image deformation post-effect by using vertex shader (no pixel shader). It was effective to generate explosion/blast effect on mobile platforms.

Can someone give me hint on how to achieve this?

i think you should do that work in viewSpace,IE vertex transformed by UNITY_MATRIX_MV

@lulucifer, how exactly can I implement this kind of vertex gird based postFx with view space transform technique? It’s appreciated if you can post a simple shader or a code snippet. I have zero knowledge background on programming this kind of postFx.