I’m very interested by this feature and I tried to do this too .
Unfortunatly I’m a beginner with programming and blueprints …
But I’m curious!
Before I found this post, I already searched some informations about the seamless portal transition.
So, maybe everybody in this thread is already familiar with this … But I just want to help :
The team of the Portal game worked on an other game with this feature before Portal. The name was Narbacular Drop (Narbacular Drop | DigiPen). In this website, i found something interesting in the pdf named " Technical design document" at the 19th page. This is a short describing of the methode they used :
The creation of our portals takes place with some extremely simple trickery along with a lot of
tedious things to make it work well.
Essentially, a portal is just a textured quad. But the contents of the texture are dynamic and the
texture coordinates change based on how you’re looking at the quad.
To create the contents of the texture:
- Convert the current camera position and look vector into coordinates relative to the portal.
- Find this position and rotation in relation to the portal’s exit.
- Move the camera to the point and rotation found in step 2.
- Render the scene while culling all objects between the camera and the portal exit.
- The render surface is now the source texture for the portal and the camera should be moved back
to where it was before step 1.
To render the quad with the proper texture coordinates:
- Convert each coordinate into screen space.
- Copy the normalized screen space x and y components into the u and v coordinates of each vertex.
- Render the quad. "
I’m working step by step, and my first step is already a problem :
For now, I just tried to create a “furtive quad” ( a plane with the exact image of the background) . Ideally, if I walk trough the quad, I should see absolutely nothing special happened…
Into the blueprint of my quad :
I get the relative position of the player camera, and set its position to a 2DsceneCapture, but I always get a position offset… why ?
ps : I know …the " furtive quad " is the most stupid feature in a video game ! xD But i think it is the most important step to get a seamless portal transition.