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first create the shape in AutoCAD, extrude it, save it as 3DS, convert to mesh2,
then render. Is there some way we could have a prism type that would allow
curves instead of straight lines?. I know all about the other line types, but
frankly they are cumbersome. Ideally I would like to reads in the DXF polyline
and then use it in a prism.
The rendering I have done have been impressive to the architects and owners and
they all ask if I used AutoCAD...no, I say, I use POVRay!
Jay
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"JayWiz" <nomail@nomail> wrote:
> Is there some way we could have a prism type that would allow
> curves instead of straight lines?. I know all about the other line types, but
> frankly they are cumbersome. Ideally I would like to reads in the DXF
> polyline and then use it in a prism.
I have no idea about the DXF polyline, but doesn't any of the linear_spline /
quadratic_spline / cubic_spline / bezier_spline prism types do the job?
Then again, it seems that your problem is not so much how to represent it in
POVRay scene language, but the workflow of getting it from DXF to there
without going via braindead triangle meshes, right?
Maybe it's time for a project aimed at getting different file formats converted
to POV SDL without reducing POV to a mere mesh renderer (after all, it *can* do
splinebased prisms, it *can* do bezier patches, it *can* do... well, quite a
lot.
.... or maybe even "include" them directly from SDL somehow?
> The rendering I have done have been impressive to the architects and owners
> and they all ask if I used AutoCAD...no, I say, I use POVRay!
Heh, great to hear  looks like it is *some* good after all ;)
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> Maybe it's time for a project aimed at getting different file formats
> converted
> to POV SDL without reducing POV to a mere mesh renderer (after all, it
> *can* do
> splinebased prisms, it *can* do bezier patches, it *can* do... well,
> quite a
> lot.
I would love a converter from STEP files to POV SDL. STEP files are a
standard format for interchange of 3D CAD data, and are made up of bounded
planes, spheres, torii and bezier patches etc. I don't know of any software
that can render these files without tesselating to a triangle mesh first.
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"clipka" <nomail@nomail> wrote:
> "JayWiz" <nomail@nomail> wrote:
> > Is there some way we could have a prism type that would allow
> > curves instead of straight lines?. I know all about the other line types, but
> > frankly they are cumbersome. Ideally I would like to reads in the DXF
> > polyline and then use it in a prism.
>
> I have no idea about the DXF polyline, but doesn't any of the linear_spline /
> quadratic_spline / cubic_spline / bezier_spline prism types do the job?
>
> Then again, it seems that your problem is not so much how to represent it in
> POVRay scene language, but the workflow of getting it from DXF to there
> without going via braindead triangle meshes, right?
>
>
> Maybe it's time for a project aimed at getting different file formats converted
> to POV SDL without reducing POV to a mere mesh renderer (after all, it *can* do
> splinebased prisms, it *can* do bezier patches, it *can* do... well, quite a
> lot.
>
> .... or maybe even "include" them directly from SDL somehow?
>
>
> > The rendering I have done have been impressive to the architects and owners
> > and they all ask if I used AutoCAD...no, I say, I use POVRay!
>
> Heh, great to hear  looks like it is *some* good after all ;)
The normal lathe uses straight lines to connect the "dots". If a curve could be
used then the polyline object from autocad (or TurboCAD which I also use) could
be easily translated. The other lathe types are not really condusive to the
objects I use. I have attached a sample image of what I show to customers and
P&D for their use.
Jay
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Attachments:
Download '90ssgmull.bmp' (577 KB)


 
 




 
 


"JayWiz" <nomail@nomail> wrote:
> The normal lathe uses straight lines to connect the "dots". If a curve could be
> used then the polyline object from autocad (or TurboCAD which I also use) could
> be easily translated. The other lathe types are not really condusive to the
> objects I use.
"Curve" is a bit vague, as all the quadratic_spline, cubic_spline and
bezier_spline would fall into that category.
I just googled for what type of spline AutoCAD's "polyline" actually is,
mathematically, only to find that it's not a classic spline at all...
From a geometric point of view, a polyline lathe should be representable as an
(albeit possibly nontrivial) CSG object composed entirely of linear_spline
lathes and tori, and a polyline prism as a CSG object composed entirely of
standard linear_spline prisms and cylinders.
So that might be a point for the ToDo list: Implement a new spline type,
defining a path made up of straight lines and circular arcs.
Question to you as someone familiar with AutoCAD: How's a polyline actually
defined in AutoCAD? Is it basically a polygon, with corners rounded using a
standard radius? Is it a polygon with corners rounded using different radius
for each corner? Or a free intermix of straight lines and arcs?
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"clipka" <nomail@nomail> wrote:
> "JayWiz" <nomail@nomail> wrote:
> > The normal lathe uses straight lines to connect the "dots". If a curve could be
> > used then the polyline object from autocad (or TurboCAD which I also use) could
> > be easily translated. The other lathe types are not really condusive to the
> > objects I use.
>
> "Curve" is a bit vague, as all the quadratic_spline, cubic_spline and
> bezier_spline would fall into that category.
>
> I just googled for what type of spline AutoCAD's "polyline" actually is,
> mathematically, only to find that it's not a classic spline at all...
>
> From a geometric point of view, a polyline lathe should be representable as an
> (albeit possibly nontrivial) CSG object composed entirely of linear_spline
> lathes and tori, and a polyline prism as a CSG object composed entirely of
> standard linear_spline prisms and cylinders.
>
>
> So that might be a point for the ToDo list: Implement a new spline type,
> defining a path made up of straight lines and circular arcs.
>
> Question to you as someone familiar with AutoCAD: How's a polyline actually
> defined in AutoCAD? Is it basically a polygon, with corners rounded using a
> standard radius? Is it a polygon with corners rounded using different radius
> for each corner? Or a free intermix of straight lines and arcs?
A polyline is defined using both straight lines and arcs.
AutoCAD uses radial as a default. The user can then redefine the curve by moving
the endpoints, start angle, end angle, and radius. It also has a center point
and a direction. With this information AutoCAD makes a corner. The corner can
be stretched (made eliptical).Perhaps for a general description, the curve
could be an elliptical curve with a circular curve as a special case. AutoCAD
stores the curve as a true curve but when it is extruded it uses a user defined
number of straight faces with smoothing normals to appear curved, which is why
AutoCAD renderings seem of low quality.
I will post a binary view of a sample rendering (with a low resolution) in the
binary newsgroup.
Jay
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in news:web.4988364b805a7c7eea031d410@news.povray.org clipka wrote:
> So that might be a point for the ToDo list: Implement a new spline
> type, defining a path made up of straight lines and circular arcs.
>
>
Iirc Ron Parker implemented a 'torusspline' like that as a macro using
sections of cylinders and torus objects.
ingo
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