Jump to content
  • Advertisement
Sign in to follow this  
hillbilly

Does the Portal Engine still work?

This topic is 4840 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

hi guys, I'm a newbie on game programming, I've read some books recently, yes, I think I can implement some algorithm under the guide of the books, but I don't konw exacctly where and when to use them.:( I plan to create a simple 3d game engin to drive my game - a RPG game, the roles can run through the streets of the city, and they can also walk in the rooms of some bulidings, It's a kind of indoor-outdoor mixed game? My puzzles are: 1) in the in-door part of my game, should I use a Portal engine? I was told that the Portal has some superiorities than the BSP algorithm. I'm also wondering if there is a new technology does the same thing? 2) does the BSP algorithm do nothing more than the collision detection under the circumstance of the emergence of the powerful vido hardware? 3) who does the frustum culling, game engin or the hardware? Is the frustum culling a standard and necessary capability of an engine? 4) in the out-dorr part of my game, are there some techniques like Portal in in-door part to accelerate the game? I only konw LOD on terrain rendering:( I will deeply appreciate you if you can indicate some things to me. thanks a lot! :)

Share this post


Link to post
Share on other sites
Advertisement
1) in the in-door part of my game, should I use a Portal engine? I was told that the Portal has some superiorities than the BSP algorithm. I'm also wondering if there is a new technology does the same thing?
Short answer: Portals are easier and BSP-trees aren't supported by hardware.
Go for portals, you'll save time and effort.

2) does the BSP algorithm do nothing more than the collision detection under the circumstance of the emergence of the powerful vido hardware?
BSP is a data structure for partitioning geometry, it doesn't do collision detection although it can be used in collision detection.

3) who does the frustum culling, game engin or the hardware? Is the frustum culling a standard and necessary capability of an engine?
Both. Hardware culls individual polygons, but the programmer is responsible for culling big sets of polygons, like entire models or rooms of a map.

4) in the out-dorr part of my game, are there some techniques like Portal in in-door part to accelerate the game? I only konw LOD on terrain rendering:(
For out door rendering, occlusion culling is a bit difficult. That's why people mostly just use frustum culling and some kind of LOD. I'd recommend the geo-mipmap algorithm. It's fairly easy to program, but before you go for something like that, you should try just to render the whole map without any fancy algorithms to see if it's fast enough. Modern hardware is pretty fast and you'll waste time programming algorithms that won't make your game work any better.

Share this post


Link to post
Share on other sites
For modern interior graphics rendering a portal system seems like a good idea, but there are a couple of different ways of implementing the algorithm that I'll mention. Most tutorials I've come across clip the view frustum to each portal, which, if portals are carefully shaped and placed, can give reasonable results. However, it require a lot of computation, and it's easy to end up with a lot of small, expensive volumes. A better method is to instead project each portal into screen space, calculate its bounding rectangle, and clip that instead. Although I haven't implemented this technique myself, I understand that it's significantly faster.

Share this post


Link to post
Share on other sites
I have implemented this method (screenspace clipping) and it works great. One of my favorite aspects of portal rendering is how easily it integrates with other rendering methods, and IMO there's not a more elegant solution for visibility culling. Portals rock my socks!!

Share this post


Link to post
Share on other sites
Portals are great, still used today, but don't overuse them. Mr. Carmack could have thought about something else along with his portals from Quake 1 up until now. Because frankly, I am sick of his indoor action (only corridors and doors), and HL2 came to a blessing to me with all its free spaces, after hours playing in the dark corridors of Doom3.

Share this post


Link to post
Share on other sites
Why I like Halo...it's a good combination of that stuff. I thought Q3 used BSP and Portals? I'm confizzled. (Microsoft Halo does BSP with PVS, don't ask how I know)

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!