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allked
Neophyte

5 Posts

Posted - Oct 30 2005 :  04:51:08 AM  Show Profile  Reply with Quote
"rhw"

ps:what do you ofen say when you people getting angry?
like f***,mother f***er , is there anything else?
i am interesting in your way of bad speaking.(clear?idon'tthinkso)

Scorpion_Blood
Warrior

Portugal
118 Posts

Posted - Oct 30 2005 :  12:04:15 PM  Show Profile  Click to see Scorpion_Blood's MSN Messenger address  Reply with Quote
i have a anti-stress ball so i dont get hungry to often LOOOL kidding :P

anyway why u wanna know that? confusing

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Walrus
Squire

Slovenia
34 Posts

Posted - Oct 30 2005 :  12:27:15 PM  Show Profile  Reply with Quote
Yeah, it is a very unusual question, to say the least...
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Eric Coleman
Gladiator

USA
811 Posts

Posted - Oct 30 2005 :  9:31:32 PM  Show Profile  Visit Eric Coleman's Homepage  Reply with Quote
What does "rhw" mean?

In the context of game programming it meants the "reciprocal homogenous W-coordinate."

In 3D mathematics it can be helpfull to use a "homogenous" coordinate system to make certain mathmatical equations easier to combine. A homogenous system, for game programming, is achieved by using an extra number explicitly defined to be either 1 or 0 depending on the mathematical context of the vector. The W coordinate is not a coordinate at all because it is dependent on the X, Y and Z coordinates. W is really f(X,Y,Z), thus a 4D vector is really only 3D.

If given a vector of (0.5, 2, 1, .25), then the "rhw" is simply 1/.25 because if you multiply the vector by 1/w you normalize it. The vector then becomes (2, 8, 4, 1), where W is normalized to 1. When W = 0 then rhw is undefined, and that has the special meaning that the values for X,Y,Z represent a point or coordinate, which is not the same meaning as a vector.
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hotrodx
Squire

43 Posts

Posted - Nov 02 2005 :  12:53:44 AM  Show Profile  Reply with Quote
Ha! This is why I love visiting these forums. You always learn something new.
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cbx
Swordmaster

Canada
296 Posts

Posted - Nov 11 2005 :  05:48:10 AM  Show Profile  Visit cbx's Homepage  Send cbx an ICQ Message  Click to see cbx's MSN Messenger address  Send cbx a Yahoo! Message  Reply with Quote
quote:
Originally posted by Eric Coleman

What does "rhw" mean?

In the context of game programming it meants the "reciprocal homogenous W-coordinate."

In 3D mathematics it can be helpfull to use a "homogenous" coordinate system to make certain mathmatical equations easier to combine. A homogenous system, for game programming, is achieved by using an extra number explicitly defined to be either 1 or 0 depending on the mathematical context of the vector. The W coordinate is not a coordinate at all because it is dependent on the X, Y and Z coordinates. W is really f(X,Y,Z), thus a 4D vector is really only 3D.

If given a vector of (0.5, 2, 1, .25), then the "rhw" is simply 1/.25 because if you multiply the vector by 1/w you normalize it. The vector then becomes (2, 8, 4, 1), where W is normalized to 1. When W = 0 then rhw is undefined, and that has the special meaning that the values for X,Y,Z represent a point or coordinate, which is not the same meaning as a vector.



Zing! Over my head.

Geeze Eric your head is just as filled up with usless information as mine! Note to allked, forget the mysteriously mysticle "W" and use the matrix.OrthoOffCenterLH found in DirectX (I'm assuming you are using DX) Trust me it just makes life simpler.

Created by: X
http://www.createdbyx.com/
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Threshold
Squire

USA
44 Posts

Posted - Nov 26 2005 :  9:51:25 PM  Show Profile  Reply with Quote
I remember reading the meaning of that acronym in the DX8 SDK and saying to myself, "Yeah, just pretend that's not there."


Life is short. They say "don't waste it, have fun." They're right, don't waste it...but DO redefine "fun."
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