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 CAD / Development / 10111
10110  |  10112
Subject: 
Re: Rendering implementation details
Newsgroups: 
lugnet.cad.dev
Date: 
Sun, 30 Jan 2005 21:42:49 GMT
Viewed: 
1933 times
  
Don Heyse wrote:
But wait, If you can make a program to fix winding on the fly then make
a tool for ldraw.org so it can be added to the part submission process.
Then we can run it on all the parts so nobody ever has to fix them on
the fly again.  That'll make *all* the renderers faster.

It doesn't matter, actually.

In one way or another, optional lines are required.

In general, the "magic halo" effect only highlights _outside_ edges, but
for a non-convex object, that won't necessarily be adqeuate.

You can't even get away with drawing only edges on the back facing
polygons and then filling for fore-facing polygons to highlight the
outer edges because you don't actually want to draw every edge if it's
part of a rounded surface.   You can't count on fore-facing polygons to
overwrite the extraneous edges because the object may be translucent and
you would be able to see all those extra edges with that approach.

The only thing you can do is runtime checking that is dependant on
either the viewpoint or the current transformation matrix which can't be
put into any sort of display list.

But sure, if people want, I can make a C utility to process an ldraw
file, and orient all the polygons in it the same way.  It's too
computationally intensive to be anything more than a pre-processing
step, but it's conceptually simple enough that I'm sort of suprised
nobody else has done it before.

>> Mark



Message has 1 Reply:
  Re: Rendering implementation details
 
(...) It has been done before. Ildefonso Junior Zanette wrote a program called Windz, I use it all the time when I author parts. I can't remember if he publically released it. -Orion (20 years ago, 30-Jan-05, to lugnet.cad.dev)

Message is in Reply To:
  Re: Rendering implementation details
 
(...) Ok, I drew a better picture (2 planes in space and a floating eye) and I'm starting to see. Maybe you're onto something. It takes 2 surface normals and one point on the edgeline to divide space into 4 quadrants. Then you only need to figure (...) (20 years ago, 29-Jan-05, to lugnet.cad.dev)

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