plasma effect (from Unity's RenderingPluginExample42)

plasma.c

// Simple oldskool "plasma effect", a bunch of combined sine waves
// input x,y (uv-coordinates), t (time)
  		int vv = int(
				(127.0f + (127.0f * sinf(x/7.0f+t))) +
				(127.0f + (127.0f * sinf(y/5.0f-t))) +
				(127.0f + (127.0f * sinf((x+y)/6.0f-t))) +
				(127.0f + (127.0f * sinf(sqrtf(float(x*x + y*y))/4.0f-t)))
				) / 4;