Displaying ingame pictures?

[The chaser]

Your quesion confuses me...

Well, let's try a practical approach:
The player open a cell door, the screen fade to black and pictures of him and a prisoner are displayed along with texts or voices effectivelly creating a cutscene (Such pictures can actually are 3d rendition, drawing, painting... whatever).
Once the scene is completed the game return to normal gameplay.
To put it simply I want to use this system to allow VISUAL encounter with non hostile NPC, without the difficult need of new 3D models.

I suspect a "rube goldberg machine" solution but... I'm used to "Thief" modding

Err... the simpliest solution is making flashbacks, like the main game.
But, I think you can do something: You will need custom content, but it will be just a billboard.


You know about billboards, right? Well, they are very good to use and practical. You need a .mat file, but with the level editor comes the material editor, so...
What you need is a picture of the character. You will need someone to draw for you or a picture that could fit the environment. Then, make it a .dds and make a soliddiffuse material with it (put the image in diffuse). Then, create some planes. In front of the player, put a billboard, showing the cutscene.
When the player interacts with the door, fade and teleport to the plane (show text and play audio) and, if there is more dialogue, fade out, teleport the player to another plane with a billboard (a different cutscene) and fade in.
Also, try to match the environment.

I know, it seems complicated, but your idea isn't bad