Portal Remake

My achievements

• Animations and skinning
• Shadow Mapping
• Ambient Occlusion and Post-Processing
• Font Rendering & Text Rendering
• Particles
• Sceen picking and UI interactions
• Geometry- and Texture Shaders

• 4 distinct draw calls to render the portals.
• Portal shooting and linking system
• Portal teleportation
• Portal Physics transfers

My Experiences

I started my project with a prototype in Unity. The first thing I did was creating a simple screen that had a camera linked to it. When the player moves, the portal-camera moves in the same way, except relative to it's portal rather than to the player. With this working I made sure that what the portal-camera saw was displayed onto a second screen that worked in the same way.

The next thing I had to was map the camera correctly to the screen, by using a shader. The shader took what the camera saw and cut out the parts outside of the portal, leaving the parts inside of the portal and creating the illusion of a portal.

The final thing I did in my prototype was implementing teleportation. To do so I teleported (moved) the player to the other portal once it's camera passed the initial portal's screen (by using the dot product between the camera and the portal). After I also made sure that the player was rotated along the forward of the second screen. That way they can succesfully walk out of the portal.

With our prototype out of the way, it was time for me to translate all of it into the custom Overlord Engine. Since Overlord is not a Visual Engine, this was not an easy task. I started in the same way as my prototype and created two screens with cameras that move in the same way as the player, but relative to their portals.

After the camera's were working, I started to work on shooting the portals. To do this I used a simple raycast and some rotation math to make sure the portal followed the normal of the surface it was one. I managed to make this work in no time.

My dreaded enemy this project was the teleportation, implementing this into Overlord was quite tough, but with a bunch of math I managed to do it. First I check if the player crossed the portal (via the dot product). Next I teleport (move) the traveller to the other portal. Finally I rotate the traveller so that it is facing outwards relative to the portal they just travelled to (the portal is behind them).