The portal created by the teleportation gun has a light effect (self -claiming, unclear, this light effect and light and shadow will conflict. If you open the light and television angle to the portal, there will be a card 1/4 screen on the screen.Effect, but can be solved by the following means,

Find the portalgun.cfg file and open it with a notepad.

turn up

# ENABLE RenderIn to See Through Portals?

# #

# If your PC DOES Not Support this, you will not be able to see the through portals evers was enabled. [Range: 0 ~ 1, default: 1]

I: SEETHROUGHPORTALS = 1

In this column, replace the above problems in SEETHROUGHPORTALS to change to = 0 to solve the above problems