LOD Runner
Another problem we ran across was the need to change distance-based systems such as level of detail (LOD) for models, because with our game, distance is relative to the portal locations. This means that the distance calculations became a choice of three lines connecting two points, rather than just one line.
Also, line of sight can pass through a single portal more than once to reach its target. The Source Engine does many pre-computed visibility optimizations for culling. Allowing users to bridge visibility leaves with portals added another level of complexity.
For better rendering, we implemented a stencil buffer drawing method for portal views, which gave us a lot of flexibility for handling the portal recursion depth.
This allowed us to render an infinitely deep number of portals (limited only by performance), which made our "infinite" hallways look pretty neat.
Stencil drawing also helped us solve the problem of integrating properly with other technology in the Source engine like HDR blooming.
Since we have to render our scenes an additional two times for our portals we poured a lot of our effort into making portals render as fast as possible, such as special view frustum culling based on the portal's edges, and render list optimizations for portal drawing.
The Orange Box
When we started working on Portal, we didn't know that it was going to be packaged inside The Orange Box with Half-Life 2, the Half-Life episodes, and Team Fortress 2. In the end, though, we're certainly glad it was. We took plenty of risks with Portal; the game is short; it features a new gameplay concept, and it's a puzzle-based game with a story.
Under normal circumstances, it would be extremely challenging to market an experimental project like Portal. Placing the game in The Orange Box alongside a well-known franchise allowed us to present a new concept to a wider base of players than we could have if it were only sold as a standalone game. In retrospect, packaging a new franchise as a smaller game amongst two well-known IPs is a low-risk way of testing its potential.
Though two years is a short development cycle in comparison to some other games, it was definitely plenty of hard work. Now that we're at the end of the Cinderella story of Portal's creation, it's just incredibly gratifying to hear how many people have enjoyed the game, and that all of our efforts have paid off.
Despite the common wisdom that gamers simply want to play the same basic concepts over and over again, Portal is happy proof that, when approached in the right way, original gameplay and narrative elements can produce fun, memorable, and most importantly for everyone's ongoing employment, successful games. The medium still has a lot of unexplored territory, and we're certainly looking forward to striking out into the unknown.
Game Data
Portal
Publisher: Valve
Number of Full-Time Developers: 8
Number of Contractors: 0
Length of Development: 26 months
Release Date: October 10, 2007
Platforms:
PC Windows
Xbox 360
PlayStation 3 (Developed in conjunction with EA)
Development Hardware:
AMD and Intel CPUs
DirectX 8-9
ATI and Nvidia GPUs
256-4GB RAM
Development Software:
Softimage XSI
Visual Studio 2005
Adobe PhotoShop and Illustrator
Perforce
ZBrush
Sound Forge
Havok
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Is it time for a new generation of puzzle games now?
While Valve have shown themselves experts at playtesting singleplayer games and making their games more accessible, I have to say this seems to have been at the expense of destructively testing their products to the full (specifically TF2, since it's not essentially a ported mod with minor changes).
The decision to give an overpowering +50HP to the Backburner Pyro, the ignorance of the impact of achievement farming on TF2 and where it left the average player, the Medic Uber exploit, the dominant Scout-rush strategy in no-doors Granary, the many Engy structure exploits and shooting-through-doors exploits. Most of not all of these should come up in destructive testing if there enough testers working for long enough on the project.
Valve's 'everyman' approach to testing and job titling has certainly proved itself for humans-versus-AI play, but for multiplayer too much is still being left for the public to guinea-pig first. The latest test case being the Matchmaking Lobby system for the Left 4 Dead pre-order demo, which is surely just a dressed-up, closed beta test they actually got the testers to pay for first.
The very scant information on the Matchmaking system before pre-orders began and before the demo's release shows Valve were very hesitant on this feature, and the speed that the normal server browser was re-implemented shows that they weren't sure enough about the Lobby system to totally remove the server browser. The pre-order demo is a way of testing the product before an improved demo is released to the public, in the full knowledge that anyone put off by the first demo has already pre-ordered on Steam. So no money can be lost while Valve irons out the creases in L4D's Matchmaker, which they will hopefully have fixed or in a better working state by the time the demo is released to the general public.
Clever business move, but I'd prefer it if they'd be more transparent about it like they were with TF2 where they actually called the Beta a Beta.