1. 3D math
- Posted by mwfch at MWEB.CO.ZA
Apr 24, 2001
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Lo !
No , i`m not dead yet . Well , now i got a question . I dont understand =
the stuff behind 3D . Like , I do know where the X and the Y is ( and I =
know i to do calculations for them like x = x+1 and so on ) , but Z ? =
I dont think so ! And I dont fully understand what i should do with this =
: x = x/z and y=y/z . I know that that is the 2D form of the 3D . =
Sorry , i dont even know wat i`m saying , but it all boils down to one =
thing : I dont understand 3D code , and you are going to show me how . =
You are going to show me how , dont you ? Please ? Thanks !
You da man/woman !
Well , read ya later !
Ferdinand Greyling (DukeFungus)
I was there in the begining of code , and i will be there in the end of =
code , but i still dont know what the hell is going on ! lol !
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<DIV>Lo !</DIV>
<DIV>No , i`m not dead yet . Well , now i got a question . I dont =
understand the=20
stuff behind 3D . Like , I do know where the X and the Y is ( and I know =
i to do=20
calculations for them like x =3D x+1 and so on ) , but Z ? I dont think =
so !=20
And I dont fully understand what i should do with this : x =3D =
x/z and=20
y=3Dy/z . I know that that is the 2D form of the 3D . Sorry , i dont =
even know wat=20
i`m saying , but it all boils down to one thing : I dont understand =
3D code=20
, and you are going to show me how . You are going to show me how , dont =
you ?=20
Please ? Thanks !</DIV>
<DIV>You da man/woman !</DIV>
<DIV> </DIV>
<DIV>Well , read ya later !</DIV>
<DIV>Ferdinand Greyling (DukeFungus)</DIV>
<DIV>I was there in the begining of code , and i will be there in the =
end of=20
code , but i still dont know what the hell is going on ! lol=20
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2. Re: 3D math
- Posted by mwfch at MWEB.CO.ZA
Apr 26, 2001
Thanks a lot , that cleard it up a lot !
Read ya later !
Ferdinand Greyling(DukeFungus)
----- Original Message -----
From: Chris Bensler <bensler at mailops.com>
To: <EUforum at topica.com>
Subject: RE: 3D math
> >
>
> Hi Ferdinand,
>
> Here is how it works.. (I may be mistaken, I haven't done 3d code in a
> while)
>
> You start with your 3d point (X,Y,Z)
>
> the formula for converting to screen coordinates is..
>
> X = (X * FOV)/Z + (screen_width/2)
> Y = (Y * FOV)/Z + (screen_height/2)
>
> FOV is the Field Of View, which is just so your 3d objects arent very,
> very small.. Usually FOV is 256 or something close to that. It's up to
> you.
>
> Z is in the range >0 to FOV..
> a big Zvalue is closer , a small Zvalue is farther
>
> make sure you test to make sure Z is never 0, or you will get a divide
> _by_zero error.
>
> I don't understand it very well myself.. I just get it to work and then
> I'm happy . :P
>
> here is some example code in C some docs I have....
> I just draws a dot in 3d
>
> -- EXAMPLE
> x = 1
> y = 1
> z = 256
> FOV = 256
> while (gx<320) and (gx>-1) and (gy<200) and (gy>-1)
> gx = x * FOV / z + 160 ; center = the center of the screen
> gy = y * FOV / z + 100 ; (mode 320x200)
> putpixel(gx,gy,15)
> z = z - 1
> if (z = 0)
> z = -1 ; just to ensure...
> endif
> endwhile
> -- END of EXAMPLE
>
> NOTE..
> You can get rid of the FOV if Z is in the range 0.1 to 1.0
>
> Hope that helps..
>
<snip>
> >
> >
