Implementation of a stencil shader

In video games it often happens that characters or objects of particular interest are occluded by more unimportant things like the scenery. To show the player anyways I created a utility shader. The shader is a combination of a vertex displacement shader and a stencil shader.

The stencil shader uses the stencil buffer to keep the player object permanently visible.

The vertex displacement shader makes sure that the vertices of a sphere are displaced over time in a noise pattern. This creates a bubble effect around the player. This bubble is also animated and is dynamically scaled as soon as the object is hidden.