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Dark GDK / Mixed up dimensions in 3D?

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Murloc
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Location: Utena,Lithuania
Posted: 27th Jan 2009 20:39 Edited at: 27th Jan 2009 20:43
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Today I have discovered one very very silly looking thing.Y and Z dimenions in 3D were mixed up! I have tried to make a terrain with heightmap,by scaling it. When I reduced Z I thought that it will be lower,but I mistaken... It became shrinked but not in height but in lenght I think. When I have changed Y value it became lower! So stupid damn it!

So in DARKGDK it is:
X-Width
Y-Height (?????)
Z-Lenght (?????)

What the...? Is there any solution for switching Y with Z?

EDIT: soz for grammar. Not very good in English :3

Theory-When you know everything,but nothing works.
Practice-When everything works,but you don't know why.
Programming merges these two-Nothing works,and you don't know why.
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code master
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Location: Illinois
Posted: 27th Jan 2009 20:59
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That's how it's done.

You could write custom functions to reverse them...

I would suggest getting used to it, as it's very common in Game Programming.

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jezza
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Location: Bham, UK
Posted: 27th Jan 2009 21:23
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Why is that wrong. It is an extension of normal 2D cartesian co-ordinates:

y
^
|
|
|______>x

so for 3D one just adds depth:
y
^ z
| ^
| /
|/______>x
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Dark Inferno Studios
18
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Location: United Kingdom
Posted: 27th Jan 2009 21:38
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Hi Murloc,
In 2D cartesian it is:

y
^
|
|
|______>x

Just like jezza said, but in 3D cartesian, he's wrong, it's actually:

z
|
/ \
x y

Hope this helps.

-Mike
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Zuka
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Posted: 27th Jan 2009 23:08
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Actually, the DirectX standard is Y-up.
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dark coder
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Posted: 28th Jan 2009 04:56
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Both are valid, however I find that Y being up actually make sense unless you're looking at a map so get used to it. Both OGL, D3D and classical mathematics use Y as up(You've never heard of along the corridor(X) and up the stairs(Y)?), it's only in engineering areas such as CAD software that I see Z as up, so if anything Z being up is stupid and wrong.

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Murloc
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Posted: 28th Jan 2009 06:01 Edited at: 28th Jan 2009 06:12
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Thanks guys. I have beed coding with software which had X for lenght Y for width and Z for height,so now it is not logic for me.. Still gonna get used to this..

Theory-When you know everything,but nothing works.
Practice-When everything works,but you don't know why.
Programming merges these two-Nothing works,and you don't know why.
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Lilith
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Posted: 28th Jan 2009 06:25
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That's why I stick with 2D.

Seriously, my college geometry initially dealt with x and y only then added z later as a mutually perpendicular axis. Totally logical when restricted to two dimensions for demo purposes. Your video screen is similarly limited and since it plot x/y on the 2D surface it's probably easier to keep those where they are.

What I don't understand is why they went with a left-hand system. I'd expect positive Z to come toward the "viewer."

Lilith, Night Butterfly
I'm not a programmer but I play one in the office
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dark coder
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Posted: 28th Jan 2009 10:01
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Quote: "What I don't understand is why they went with a left-hand system. I'd expect positive Z to come toward the "viewer.""


What value would then be at the camera position? Something exceptionally high? Remember that using IEEE754 floats the accuracy of the values isn't linear as with integers, but you have higher decimal precision at lower exponents as you have a finite amount of significant figures the float will be accurate to. So if the camera is at 0,0,10000000 then the Z-depth accuracy at that range would be abysmal.

I think the system makes perfect sense, once vertices of a model are transformed anything at 0,0,0 is directly on the camera, anything down the Z axis will be farther from the camera, X to the sides and Y vertically.

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entomophobiac
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Posted: 28th Jan 2009 10:48
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Someone claimed that this mixup started in 3D tools like 3D Studio. They chose or simply happened to put the Z-depth on the wrong axis and the phenomenon has remained in the industry ever since.

Most tools suffer from the same issue, actually. It's become something of a systematic error that people believe to be true, even.
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Hayer
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Posted: 1st Feb 2009 14:32
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@ entomophobiac

I belive u failed. Links to trusted sites and I may consindering beliving u.

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jason p sage
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Posted: 2nd Feb 2009 01:57
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My Word - Such Hostility... "Stupid" "Failed" LOL


http://www.jasonpetersage.com/?PAGE=ironinfantry&SECTION=ironinfantry
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Zuka
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Posted: 2nd Feb 2009 02:02
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Crazy bastards. Get along!
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DGZ
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Posted: 2nd Feb 2009 03:39
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I bet you were using GameMaker at first, weren't you? I use it too (not too much anymore though), and I got a bit mixed up for a few minutes while I tried to figure out why my Terrain was growing shorter, instead of higher.

What does the variable 'c' represent in the equation 'E = MC^2'? Get it right, and I'll give you a cyber cookie.
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