POV-Ray : Newsgroups : povray.advanced-users : coordinate system handedness Server Time
1 Nov 2024 09:20:15 EDT (-0400)
  coordinate system handedness (Message 1 to 2 of 2)  
From: Andycadd
Subject: coordinate system handedness
Date: 12 Nov 2006 10:30:01
Message: <web.45573c7cae5e5b5afedbe4b90@news.povray.org>
I use autocad always have always will

I have written a converter taking the faces etc... and converting them into
triangles, no problems when the coordinate system of the target objects are
from the default directions.

I use the autocad "block" structure linked to "include files" no problems,
this allows me to use the povray primitives and more advanced objects as
povray entities (spheres, box, prism, torus, blobs etc..... I use linked
attributes within the autocad blocks to carry additional parameters)

the whole system works very well with automated texturing (autocad layers),
include file placement(blocks) etc... I am very happy with it

my problem comes from autocad:

Autocad allows "blocks" (what I use as includes) to be placed in an
alternate coordinate system, scaled, then a rotation is applied, after
which a translation (within that alternate coordinate system) occurs.

my autocad input data starts like this  (name) (coord sytem vector  X,Y,Z )
(size X,Y,Z) (rotation  counterclockwise radians) (location translation
X,Y,Z)

what I do now is (place) (scale) (rotate) (translate)

I cannot consistantly get the correct rotation within the alternate
coordinate system, I have tried a multitude of permutations, but there is
always at least 2 out of 8 items which come in off, especially when the
initial coordinate system has a negative value someshere.

Has anyone else wrestled with the coordinate system handedness problem as it
relates to autocad.

My output povray files use the up <0,0,1> already (using povray like a
drafting program)

I think the problem lies with the initial 0 direction of rotation

any and all incites would be greatly appreciated

I posted a couple of startup renders in the pictures group from "andycadd"
these are mostly triangle based but I use a few povray items spheres,boxes
etc... if I can get this problem worked out I can use a lot more of the
povray items embedded within my include files, instead of only using
includes from the vertical coordinate system

thanks in advance

Andrew Giedraitis
and### [at] comcastnet


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From: kurtz le pirate
Subject: Re: coordinate system handedness
Date: 12 Nov 2006 14:23:03
Message: <kurtzlepirate-BC3E09.20230212112006@news.povray.org>
In article <web.45573c7cae5e5b5afedbe4b90@news.povray.org>,
 "Andycadd" <And### [at] comcastnet> wrote:

about "handedness" have you read this :

 - <http://www.povray.org/documentation/view/3.6.1/15/>
 - <http://tag.povray.org/povQandT/morayQandT.html>


-- 
klp


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