Alright well this is my first tutorial so it might not be the best. I'm going to explain how to use the Render To Texture (RTT) feature in the cutscene editor .Render to Texture allows you to render the view of a camera onto a texture. This is useful for things such as television screens, mirrors, and other similar objects. This is a very simple tutorial though I recommend you have at least some background with the cutscene editor before attempting this.
Render To Texture Method 1
First come to first we want to open up the cutscene editor. After doing this we want to make sure we have Campaign Mode enabled. To do this go to Render and find and make sure Campaign Mode is checked on.
Next we will add a model with the RTT Texture. In my example I will be using SMHyperionBridgeBriefingCenter coincidentally the same model blizzard uses in their example picture.Once you add this you'll want to make sure you can see it so make sure it's facing you, you'll know by the gray siding otherwise it will seem like nothing is there.
Now you'll want to add a camera for this. Unfortunately we cannot use just any cameras. We must use cameras inside of models. Such as the cameras in several of the SM sets and portraits. I recommend using the Test Camera model. While you won't be able to see this model which makes it a pain to see where it's pointing, however once the RTT channel is setup you should be able to get it pointing at the place you want fairly simply.
Finally we will add a RTT node. To do so go to Object then Add Node and select Render To Target (RTT) I know it doesn't say Render to Texture don't question it.
Finally we need to set the RTT Channel ,by left clicking on the added RTT node, to Channel to 0, which I've found to be the most common channel used. Only channels 0 to 6 are usable. Finally set the camera, by right clicking the RTT node, to the Test Camera we added earlier.
Congratulations! it should now be working, if it is not then reread and find your mistake. Now you can reposition Test Camera to where you want it to be pointing and your now done setting up RTT.
Render To Texture Method 2
Thanks to Zolden & DrSuperEvil for discovering how this method works. This method is currently the only applicable way to use RTT outside of the Cutscene Editor. This will be something very similar but it won't work as nicely as Method 1 and to my knowledge you must import Zolden's RTT Model attached below. Now for the tutorial.
This method is very easy if you have a semi decent understanding of the data editor. If you do you can probably do the next step more efficiently and easier.
Data Editor - Model Tab
Find the Marine model.
Edit the (Basic) Art: Model to be your imported model stated above and attached below. Then place the "Marine" on the map with several other units. This could really be any unit but to make things easy this is the unit I chose.
Create a new Trigger and name it RTT.
Add the Event - Map Initialization.
Add an Action - Set Camera Channel
Modify the CameraUnit to be one of your placed marines.
Modify the Camera Name and select Choose Camera From Model and select SC2Camera001.
It may be a lieelt bit offtopic, but still: do you know how to make dialog or dialog item translate RTT chanel? There is a trigger for it, but looks like something else should be done besides, to see the picture from camera.
For those who want to use this in game and don't know how, I post an example map, which I created with DrSuperEvil's assistance.
There is an imported model ch1.m3, which includes a model camera and a mesh with RTT channel 1 on material's emissive layer (that's why the picture from camera is a bit brighter than it would be if I activate rtt channel on diffuse layer).
I used this model as marine's model, and set one of the marine's camera to channel one by a trigger. So all marines become something like teletubbies, but without a colorful monster around the screen.
The trigger we set camera to channel with is player specific. For example, we set camera A to channel 1 for player 1, and camera B to channel 1 for player 2. How will this work? I think, players will see picture from different cameras on the same unit.
"Use RTT for dialog" trigger doesn't have player specificity, but we can create a dialog per player. In case we ever realize how to make dialog show the picture from camera.
There are 7 channels, but they seem to use different picture quility. In max, where you define RTT for a layer, each channel has quality characteristic: 1 - high, 2, 3 - medium, and so on. But even high quality channel 1 doesn't show skybox and some actors. For example, in some tests channel 1 show doodads, in others - doesn't. And I never saw it shows launch/impact visuals.
My guess with set dialog RTT channel is that it also has to interact with "Set camera channel on portrait". But i've yet to be able to get it to show a picture
I don't want to be able to see all the doodads in fact could be an interesting way of making it unique, but I still want to figure out how to make the picture show onto a dialog item cause that would be boss.
Edit: Just thought of this I haven't been setting portrait channel. Maybe that's the key to it finally, now i'm gonna test that. That causes the models to display the portrait though.