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Hello, I have some LDraw animation projects in mind and am starting by making a simple viewer using OpenGL. I have a program that will read a file and display it, but I run into problems with the shading because it only does flat shading. I think I (...) (20 years ago, 7-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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(...) I suspect this has been talked about in this group before, but probably not all in one thread. I'll try to summarize the things to look out for. First of all, you are correct in that any files that aren't BFC-certified have polygons with (...) (20 years ago, 7-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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(...) <SNIP> (...) That does help a lot. Thanks much. Brian Durney (20 years ago, 9-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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(...) [snip] (...) [snip] (...) It is neither impossible nor particularly hard. I will snip the rest of the post here and explain. There is an interesting property of closed surfaces that can allow you to determine the normals for all polygons (or (...) (20 years ago, 11-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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(...) I don't know about that goal. I think it's better to make it easy to assemble the various primitives into parts. That way we get more people volunteering to make the parts. I don't think the primitives *can* be closed. I also think it's much (...) (20 years ago, 11-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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(...) All: It is dangerous to write technical arguments at 1:30 in the morning, and I made some serious mistakes in my post above. 1) You are correct that most LDRAW parts are not closed and probably never will be. Optimizing for ease of part (...) (20 years ago, 11-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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I'm working on just such a utility right now. I hope to have some beta code in a few days : ) (...) (20 years ago, 11-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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I won't argue with your clarification, but I will point out that it would be more difficult for a renderer to perform this feat, particularly one that is designed as a real-time renderer, and therefore presumably has rather serious limitations on (...) (20 years ago, 12-Mar-04, to lugnet.cad.dev)
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| | Re: surface normals and vertex normals for OpenGL
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(...) With the use of a point hash table, it should be possible to do all of the analysis in linear time proprotional to the number of points in the object. So, I guess I disagree with you. Not that it particularly matters, until somebody actually (...) (20 years ago, 13-Mar-04, to lugnet.cad.dev)
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