Comments on: Table of Contents for Pygame Book http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/ Blog of Will McGugan Sun, 07 Sep 2008 20:34:18 +0000 http://wordpress.org/?v=2.3.3 By: Will http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-19330 Will Sat, 08 Mar 2008 19:03:22 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-19330 Hi wdh, I can't remember if I used the term 'local space' explicitly in the book -- I'm guessing I didn't -- but local space is simply the coordinates of a model before they are transformed. World space is the coordinates of the model after they have been transformed. I guess you have already figured that out. It is possible to work entirely with world space, but sometimes it can simplify certain calculations if you use local space. For instance if you have a complex model of a space ship and you want to test if it has come in to contact with a energy bolt (approximated by a sphere) you could transform all the points in the ship to world space and do the test... or you could transform a single point for the sphere centre to the local space of the ship model. Transforming a single point is obviously quicker than transforming many. Another example would be a game character with a certain field of view. You may have to transform other objects in to the characters local space to determin if it can see them. Hope that helps! Will Hi wdh,

I can’t remember if I used the term ‘local space’ explicitly in the book — I’m guessing I didn’t — but local space is simply the coordinates of a model before they are transformed. World space is the coordinates of the model after they have been transformed. I guess you have already figured that out.

It is possible to work entirely with world space, but sometimes it can simplify certain calculations if you use local space. For instance if you have a complex model of a space ship and you want to test if it has come in to contact with a energy bolt (approximated by a sphere) you could transform all the points in the ship to world space and do the test… or you could transform a single point for the sphere centre to the local space of the ship model. Transforming a single point is obviously quicker than transforming many.

Another example would be a game character with a certain field of view. You may have to transform other objects in to the characters local space to determin if it can see them.

Hope that helps!

Will

]]> By: wdh http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-19328 wdh Sat, 08 Mar 2008 18:00:53 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-19328 I bought a copy of the book a while back and you've certainly got me hooked on game programming, but have a question I'd like to ask about the use of 3D with Pygame. Many game development web sites talk about the concepts of "world space" (an entity's position relative to the game world's origin) and "local space" (an entity's position/orientation relative to it's own origin), but your book does not mention these concepts as far as I can tell (this is not a criticism by the way, just a curiosity). Google does not reveal anything on the topic relating to Python/Pygame whatsoever. I've read that vectors and points can be transformed from world space to local space and vice versa using matrices, but to be honest I don't really understand why you need local space at all. Most examples talk about local space as being useful when you need to calculate positions of other objects relative to the object whose local space you are using, but as you demonstrate in the book with the soldier/droid example on page 168, this is perfectly possible in what I understand to be "world space". I'm fairly certain I'm just missing something due to a lack of understanding (hey, I'm a novice) but I'd be interested to know what your thoughts are on the above. Do you make the distinction between world and local space in your more advanced games, i.e. are they just topics that would not fit in 300 pages? Or are they irrelevant? Thanks! I bought a copy of the book a while back and you’ve certainly got me hooked on game programming, but have a question I’d like to ask about the use of 3D with Pygame. Many game development web sites talk about the concepts of “world space” (an entity’s position relative to the game world’s origin) and “local space” (an entity’s position/orientation relative to it’s own origin), but your book does not mention these concepts as far as I can tell (this is not a criticism by the way, just a curiosity). Google does not reveal anything on the topic relating to Python/Pygame whatsoever.

I’ve read that vectors and points can be transformed from world space to local space and vice versa using matrices, but to be honest I don’t really understand why you need local space at all. Most examples talk about local space as being useful when you need to calculate positions of other objects relative to the object whose local space you are using, but as you demonstrate in the book with the soldier/droid example on page 168, this is perfectly possible in what I understand to be “world space”.

I’m fairly certain I’m just missing something due to a lack of understanding (hey, I’m a novice) but I’d be interested to know what your thoughts are on the above. Do you make the distinction between world and local space in your more advanced games, i.e. are they just topics that would not fit in 300 pages? Or are they irrelevant?

Thanks!

]]> By: Will http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-9294 Will Fri, 02 Nov 2007 09:19:08 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-9294 Hope you enjoy it Bruce! :) Hope you enjoy it Bruce! :)

]]> By: Bruce http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-9279 Bruce Fri, 02 Nov 2007 01:46:09 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-9279 I bought this book and it's awesome :) I'm on chapter 2. I bought this book and it’s awesome :)
I’m on chapter 2.

]]> By: DeanG http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7994 DeanG Mon, 08 Oct 2007 16:14:00 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7994 Sorry, I hadn't realized it was in printer. Congratulations! Guess we can chalk that list up to Wiki and Blog entry topics. :-) Sorry, I hadn’t realized it was in printer. Congratulations! Guess we can chalk that list up to Wiki and Blog entry topics. :-)

]]> By: Will http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7980 Will Mon, 08 Oct 2007 09:02:53 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7980 Dean, Those are all great topics, but the book has gone to the printers and I think I would need another book to do justice to those subjects! Maybe I can cover them in a sequel! Will Dean,

Those are all great topics, but the book has gone to the printers and I think I would need another book to do justice to those subjects! Maybe I can cover them in a sequel!

Will

]]> By: phil hassey http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7965 phil hassey Mon, 08 Oct 2007 04:40:24 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7965 Hey - I maintain the pygame website... If you want some kind of coverage there, send me an e-mail and we can figure out a "News item" to post on the front page, or something. In the meantime, feel free to add mention of the book to the wiki. -Phil Hey -

I maintain the pygame website… If you want some kind of coverage there, send me an e-mail and we can figure out a “News item” to post on the front page, or something.

In the meantime, feel free to add mention of the book to the wiki.

-Phil

]]> By: DeanG http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7954 DeanG Mon, 08 Oct 2007 01:22:15 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7954 Very exciting stuff! I'm very glad to see Appendix B. Please consider either another chapter or appendix to summarize advanced topics. Frankly, knowing the keywords and basic approach will help [give the necessary clues to] those who will proceed from the book to the internet. Examples: Internet Play: PyGame and Networking, Threads, Twisted, Perceived and Real Limitations (side scrollers?), Cross Platform concerns, Beyond CPython: Stackless, IronPython/Mono and Jython?, Screenshots and Printing, Adding Scripting to your Game....better stop before I completely discredit myself. ;-) Very exciting stuff!
I’m very glad to see Appendix B. Please consider either another chapter or appendix to summarize advanced topics. Frankly, knowing the keywords and basic approach will help [give the necessary clues to] those who will proceed from the book to the internet. Examples: Internet Play: PyGame and Networking, Threads, Twisted, Perceived and Real Limitations (side scrollers?), Cross Platform concerns, Beyond CPython: Stackless, IronPython/Mono and Jython?, Screenshots and Printing, Adding Scripting to your Game….better stop before I completely discredit myself. ;-)

]]> By: Tennessee Leeuwenburg http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7927 Tennessee Leeuwenburg Sun, 07 Oct 2007 23:58:03 +0000 http://www.willmcgugan.com/2007/10/07/table-of-contents-for-pygame-book/#comment-7927 Hi Will, I am the Editor-In-Chief of "The Python Papers". I'd love to include something covering your book in our next issue. If you'd be interested in contributing a little content, I'd love to give you some air-time. Contact me at tleeuwenburg@gmail.com if you are interested. Cheers, -T Hi Will,

I am the Editor-In-Chief of “The Python Papers”. I’d love to include something covering your book in our next issue. If you’d be interested in contributing a little content, I’d love to give you some air-time.

Contact me at tleeuwenburg@gmail.com if you are interested.

Cheers,
-T

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