• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
wh1sp3rik

Algorithm for generating indices

10 posts in this topic

Hello,

 

I coded a function, which takes as a input a vertex buffer. Output is a vertex buffer with removed duplications and index buffer.

It's working well, but the main problem of this function is, it's very slow. It contains three for loop and its complexity is roughly O( n^2 * log n ).

 

I just go though vertex array and adding index numbers, but when duplication is found, i delete it, i have to search, what index this duplication had and used it. Of course, i have to search whole vertex array again and again and search for duplication. ( i am comparing not only vertices, but normals, uvs too, they have to be same then i can mark it as duplication )

 

I would like to ask, if you know any technique, which is faster. I am searching the internet and i still did not find aynthing :(

 

thank you very much.

0

Share this post


Link to post
Share on other sites

Linear time, wau.

 

When i am building that hash and storing what i have seen so far, it's getting bigger and bigger and i have to search it to find a vertex if it's there or not, it doesn't look like linear. Perhaps i have to think about it more smile.png it will be nice to see some pseudocode.

 

thank you

 

edit: i just saw some small examples using hashes and i have a better view now

edit2: there can be another problem, most of verticles don't have to be exact same, but there can be small difference 0.001, so these will be "warped" into one.

Edited by wh1sp3rik
0

Share this post


Link to post
Share on other sites

It seems to me that if indexing would be a significant optimization, then you preferably would want some kind of shared-node structure where you don't need to post-process vertices. But that might not always be easy to do, depending of where the vertices are originated.

1

Share this post


Link to post
Share on other sites

This is for my exporter to my model format. I would like to make indices and sort them, but my current solution .. is working, but it's not fast :)

 

I checked the hashing. it looks like, the main problem is, duplicates doesn't mean same values but values which are VERY close to be same ( for example two vertex very very very close to each other ).

1

Share this post


Link to post
Share on other sites
Suggestion: How about hashing by rounded floating point values. Edited by Chris_J_H
2

Share this post


Link to post
Share on other sites

Chris: Yep, that's good idea :)

 

I have no experience in hashing. Let's say, it's a function, where input gives you an index for an array.

How do i hash a struct, where are vertex positions, normals, uvs and colours? should i hash a part of memory, where struct is stored ?

0

Share this post


Link to post
Share on other sites
You can change my algorithm into something that uses a k-d tree to look for the closes vertex and now I believe the algorithm is O(n*log(n)).

Merging vertices that are close is a messy problem, and one that I would be careful to specify much more precisely than you have in this thread. Rounding will work in many instances, because 9.631 and 9.633 will round to the same box; but 9.999 and 10.001 might round differently, even though they are just as close as the other two.

You have to think about the non-transitivity of the "is close to" relationship. If my model has a million equally-spaced vertices joining (0,0,0) and (10,10,10), do you meld them all into a single vertex, or partition them into groups?
0

Share this post


Link to post
Share on other sites

Another method:

 

- Assign every vertex an index

- Create an array of vertex-count number of pointers to indices and set all pointers to null.

- Loop over all vertices in all triangles and create indices whenever a vertex' element in the index-array is still null -> assign new indices to the array

1

Share this post


Link to post
Share on other sites

I have headache from it, lol.

 

It seems .. i will just drop a "duplicating vertex, when their distance is very small" feature ... graphic designer should be careful, where he puts verticles hehe.

Then .. i can use hash table and a great function called "IsVertexAlreadyInTable". That should help.

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0