Subject:
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Re: POV-Ray help needed
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Newsgroups:
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lugnet.cad.dev
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Date:
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Thu, 26 Jun 2008 14:42:29 GMT
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Viewed:
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14455 times
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Travis Cobbs wrote:
> A few things.
>
> First of all, both the LDraw file format and the POV file format support
> hierarchical compositions, so I think it's a good idea to leave things in their
> original hierarchy. So, instead of having a POV object for each part that is
> made up entirely of one single mesh2 object, with all the geometry for the part,
> it should instead contain a mesh2 object for all the type 3 and 4 lines in the
> part, but then references to the part's primitives and subfiles (which
> themselves are constructed in the same way). This would significantly decrease
> the file size of the generated POV file.
Actually I was planning to support both to see which approach renders
faster. Having the vertex and index data in memory, the mesh2 approach
was the easiest step to begin with. I only had to correct for quad ->
triangle conversion to get something usable in POV-Ray.
>
> Secondly, primitive substitution helps a lot. At the very least, I think you
> should support primitive substitution for cylindrical primitives, since there
> are so many studs. This improves the final result noticeably. If you're
> interested, I have a class (in C++) that parses an LDraw filename and then
> automatically determines if it is a primitive, and if it is a primitive,
> extracts all the pertinant info from the filename. (For example, if you feed it
> 4-4cyli.dat, it knows that it's a cylinder, and knows that the cylinder fraction
> is 1.0. 2-4cyli.dat is recognized as a cylinder with a fraction of 0.5.)
Yes primitive substitution is on my to do list (for the recursive
approach, I don't see an easy way of doing it with the mesh2 approach).
But I wanted to get a 'simple' export on the road first.
> I also have code in LDView that generates a POV camera statement that exactly
> matches LDView's view (assuming the POV output has the same aspect ratio as the
> LDView view). If you're having trouble with your camera angle, you might be
> interested in that code.
That could be interesting, My problem at the moment is indeed finding
the correct camera angle. Point is I do not (always) have access to
OpenGL during export so I have to recreate the camera with the eye, up
and lookat vectors I also us for gluLookAt. I also copy the 60 degree
FOV I use in gluPerspective.
But like said this does not give the wanted result, the 'zoom' is off. I
am now looking into using the OpenGL frustum as a starting point in
finding the angle.
> As for material properties, I can't really help you much there. Different
> people have come up with different material properties for the various LDraw
> colors with differing levels of apparent match to real life bricks. The thing
> is, different material definitions produce different results based on the render
> settings. Radiosity and HDR light field renders in POV can look very realistic,
> but they can also be very slow to render. And the material properties that look
> best for those will probably not match the material properties that look best
> for other lighting models.
Yes colors are largely a user thing, but I would like to supply a decent
'default' set of materials generated from the color palette used in
LD4DStudio. The application has a color configuration file which can be
merged with the ldraw config file to get the maximum amount of colors. I
was planning to add specific povray properties to my custom colors xml file.
> One thing to do here is to give users the opportunity to include their own
> custom include file at the top of your output. Then, enclose all of your color
> definitions in #if defined blocks, so that if the user wants to redefine the
> colors, all they have to do is define them in their include, and then make the
> appropriate declares to prevent your color definitions from being used.
The #if approach like used in L3P is a good idea, thanks. I will add
some optional settings to let users automatically include some custom
pov files.
> --Travis
Thanks for your feedback.
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Message has 1 Reply:
 | | Re: POV-Ray help needed
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| (...) I believe that POV's FOV is the horizontal field of view, while OpenGL's is vertical field of view. So you have to convert from one to the other (which I do in LDView). Set your rendering window in both the OpenGL view and the POV rendering to (...) (18 years ago, 26-Jun-08, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: POV-Ray help needed
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| (...) A few things. First of all, both the LDraw file format and the POV file format support hierarchical compositions, so I think it's a good idea to leave things in their original hierarchy. So, instead of having a POV object for each part that is (...) (18 years ago, 25-Jun-08, to lugnet.cad.dev)
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