 | | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Hello, Ok guys, I already announced that I coded such a tool in Java. At present, only one Ldrawer has asked for the code. In fact, it's an alpha release. Thus, I should find beta testers first. Anyway it has already translated some pieces! Here is (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Jean-Pierre PARIS wrote in message <37F3B871.74AE196F@w...doo.fr>... (...) My algorithm doesn't require the vertices to exactly match; I was intending to pass one ray per polygon through the dat object, not an arbitrarily large number. And only if (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Gary Williams wrote in message ... (...) Okay, I made a bad assumption there, since a group of polygons may terminate flush against another polygon, without touching its edges. But still I think a performance improvement could be realized by using (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Sorry, but I think that the even/odd algorithm only work on 'correct' solids. For example, if you take a 'bad' box made of 6 faces that have holes beween them, your algorithm can lit an inside face. And in some parts, such a situation exists. (...) (25 years ago, 2-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) This isn't automatic, but what if the program interrogates the user to pick a side which is facing outward? From that information, the program could then mark-up all adjacent sides. If the program ran out of sides, it could re-interrogate for (...) (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Jean-Pierre PARIS wrote in message <37F660FB.1EC77AC9@w...doo.fr>... (...) I see where you're coming from now. You're right. (...) could (...) It's starting to sound like user intervention would be needed in most, if not all, cases. Maybe it would (...) (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Steve Bliss wrote in message <37f6c0d9.269680202@...et.com>... (...) Doh, you posted mere minutes before me and said the same thing. :) -Gary (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Instead of asking the user, the program could first try to cast rays and then only if there are any faces left it asks the user. I've started writing my own converter and it worked correctly with the 'standard' bricks but had a few problems (...) (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) you should consider that there are a lot of such groups of sides in one brick! Thus, the approach described by Leonardo is better: (...) Now, my main problem is: how can I find enough time to translate and check all the bricks! I guess my (...) (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) I really don't like programs that need user interactions for such job! Thus I tried to cast enough rays so that all the faces are being oriented correctly. Now all the std bricks are OK, without any assumption about the fact that they are (...) (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) You need to have someone to check the parts, take a look at the picture at (URL) (from 105.DAT), there's a missing face and the program won't be able to handle that. There are other parts like that, just start checking and you'll see. Leonardo (...) (25 years ago, 4-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Neither do I, but I also know how hard it is to visually check a part for errors. (...) How does that work? Is it based on what the majority of the rays deterimine? I probably need to re-read some of the messages in this thread, to get a (...) (25 years ago, 4-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Sorry Leonardo, but I checked 105 again my code: it does the right job! Ok, you can argue it's pure luck. In fact, it is! If a ray went through the hole between the flag and the rest of the piece, my code would invert the flag orientation. (...) (25 years ago, 5-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) I choose rays so that they may orient one face. With this face I use a sort of flood-fill algorithm (please try to find on of my previuos message) to orient al neighbors. Once a face is oriented, I don't look at it anymore. But, your idea (...) (25 years ago, 5-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) OK, then help out a Java-dummy: are there JDK's available on the net, or are they purchase-only? Steve (25 years ago, 6-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) I guess you can download one from (URL) (25 years ago, 6-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) My code worked too but my point was to say that the part is not correct, there could be some cases where it won't work and besides that, it won't look good if you render it with a program that has backface culling. How are you going to save (...) (25 years ago, 6-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) In this sense we agree! It would be a shame if after a so long emails exchange we didn't ;-) (...) I read .dat files in the std LDraw folders, and simply output oriented .dat files in another one. For duplicate instances, I use a folder name (...) (25 years ago, 6-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Sun's implementations are free. Some others are not. Personally I use Sun's jdks... Have a look at: (2 URLs) you are under a Windows environment As a reply to Leonardo msg: You are right, but I encourage newcomers to the Java language to use (...) (25 years ago, 6-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Thank you very much! Steve (25 years ago, 7-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) Ok, I can announce that my code actually orient ~10000 faces of 2560, BUT 4. In a previous version, 40 faces remain unoriented. After I checked all distances between the ~12000 of the part, I have discovered that some distances were very (...) (25 years ago, 15-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Hello! Eventually I finished orienting (automatically) all faces of bricks 10 and 2560! For those who are interested by the results, please have a look at (URL) the same place, one'll find the corrected 2560. Yes, this part as small bugs: 16 faces (...) (25 years ago, 21-Nov-99, to lugnet.cad.dev)
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