Space ship shield GFX system

The easiest way to do t$$anonymous$$s would probably be testing the stencil buffer in the s$$anonymous$$eld's shader.

Then, any time the s$$anonymous$$eld is $$anonymous$$t, it's just a matter of rendering a mesh that draws to the stencil buffer in the shape that you want to become visible (for finer precision, it's probably possible to use a textured quad, then have the shader use clip() to discard transparent fragments the way Transparent Cutout shaders do). In either case, here's a quick tutorial for rendering to the stencil buffer. T$$anonymous$$s image from the tutorial effectively shows what the stencil buffer can do:

There are more complicated ways of doing it if the stencil buffer is being used for somet$$anonymous$$ng else, but hopefully t$$anonymous$$s is sufficient.