Mapping:Adding a camera to your map
A portal consists of 3 to 4 objects.
First you have an object is a brush you want to be the "viewer".
Then you have 2 entities, the misc_portal_surface and the misc_portal_camera.
This tutorial also uses an entity of target_position which is used to aim your camera, although you can give your misc_portal_camera an angle to aim instead.
Images
Download the following zip file Images it contains 2 images. Extract them tore these in your images folder.
Shader
Add the following shader to your shader file, you should change the paths to match your map.
textures/myfirstmap/tvscreen { qer_editorimage textures/myfirstmap/monitor.tga q3map_lightimage textures/myfirstmap/monitor_colour.tga q3map_surfacelight 1200 portal { map textures/myfirstmap/monitor_colour.tga blendFunc filter depthWrite } { map textures/myfirstmap/monitor_colour.tga blendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA alphagen portal 256 rgbGen identityLighting } { map textures/myfirstmap/monitor.tga blendfunc blend } { map $lightmap blendfunc filter } }