Articles for college of knowledge

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Articles for college of knowledge

Post by Dexter on Wed Jul 30, 2014 12:15 pm

Hello guys,

I am on a vacation these days, so I do not have any access to my normal development PC. That said, My activities in BVE will be a bit limited in the next few days (it is called vacation for a reason  Very Happy ), but I was thinking about a few articles for the college of knowledge. I will most likely start with an article about Normals, because as far as I understand, many people are confused with this topic. Other articles will follow (cylinders, cubes, revolving bogies etc.)

Is anyone interested in contributing with his own article? Which topics would like to have explained?

D.
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Re: Articles for college of knowledge

Post by lonelyinardwick on Thu Jul 31, 2014 3:33 am

Perhaps the state of the current developments scene to give new contributors a sense of whats going on. This I wish I had the time to write about, even though I know what to write.

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Re: Articles for college of knowledge

Post by Dexter on Thu Jul 31, 2014 6:53 am

It is called "college of knowledge" for a reason. If I wanted to write about current development and stuff like that, I'd have called it "news channel", or "rumour mill". Still, apart from this reply, I do not see much interest in the offered service. Good, that means everyone knows everything and there is no need for educational articles.
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Re: Articles for college of knowledge

Post by chrisrose1993 on Thu Jul 31, 2014 10:05 am

I would appreciate an article on normals, Right now I find it's more guesswork playing with random numbers!
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Re: Articles for college of knowledge

Post by Greater Anglia Metro on Thu Jul 31, 2014 11:17 am

chrisrose1993 wrote:guesswork playing with random numbers!

That's how all my addons are made !  Laughing 
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Re: Articles for college of knowledge

Post by leezer3 on Thu Jul 31, 2014 12:39 pm

Normals are easy Smile
I'm not going to write a full article on them, but they work as follows:

Assume you have a very simple cube (This doesn't look quite right, but it's the easiest thing to use to demonstrate), which you want to add smoothing to.
This looks like this at the moment:
Code:

[MeshBuilder]
Vertex 0,0,0
Vertex 0,1,0
Vertex 0,1,1
Vertex 0,0,1
Vertex 1,0,1
Vertex 1,1,1
Vertex 1,1,0
Vertex 1,0,0
Face 3,2,1,0
Face 2,3,4,5
Face 7,6,5,4
Face 6,7,0,1

Now, for normals to work, you need to know what your faces are doing. Look at this diagram-

This represents an overhead view of our cube, with the blue numbers representing the order of the faces and the red arrows showing where each normal should go.
In other words, on a standard smoothed pair of faces, our normals should be placed on a point at an angle exactly half-way between that of the two faces.

This leaves us with a cube looking like this:
Code:
[MeshBuilder]
Vertex 0,0,0 ,-1,0,-1
Vertex 0,1,0 ,-1,0,-1
Vertex 0,1,1  ,-1,0,1
Vertex 0,0,1  ,-1,0,1
Vertex 1,0,1 ,1,0,1
Vertex 1,1,1 ,1,0,1
Vertex 1,1,0 ,1,0,-1
Vertex 1,0,0 ,1,0,-1
Face 3,2,1,0
Face 2,3,4,5
Face 7,6,5,4
Face 6,7,0,1

Moving them will effectively alter the light direction used to create the smooth shading.

Anthony Bowdens post on the subject:
http://railsimroutes.net/blog/?p=882

Cheers

Chris Lees

http://www.bvecornwall.co.uk

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Re: Articles for college of knowledge

Post by Dexter on Thu Jul 31, 2014 12:59 pm

@leezer3: Well, I wanted to write an explanatory article from a scratch, explain everything from the beginning and provide logical connections and everything.

Why does there always have to be a smartie...  Rolling Eyes   Very Happy   What's easy for you, might be difficult for others.
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Re: Articles for college of knowledge

Post by chrisrose1993 on Thu Jul 31, 2014 2:37 pm

That's actually helped a lot Chris, I thought there was some complicated way to work out the value but it's easy! Smile
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Re: Articles for college of knowledge

Post by Quork on Thu Jul 31, 2014 5:28 pm

Erm... Mind Chris explained only half the deal, about smoothing... In most cases you do not want smoothing, which means things do get more complicated; you need vertices to be doubled and trippled depending on how many faces are meeting at them. Though I won't get into detail since Dex wants to write an article on it (which I'm looking forward to!).
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Re: Articles for college of knowledge

Post by graymac on Thu Jul 31, 2014 6:01 pm

No difficulty with multiple articles on the same topic. Do scribe one, if you can. After all. there's more than one book on how to bake a cake in any library. :-)
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