OBD talk:M3GM - Revision history

Iritscen: +cat

2022-05-04T16:14:43Z

+cat

← Older revision		Revision as of 16:14, 4 May 2022
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	:Regardless of technical issues, they have to duplicate PNTA entries because a vertex can have different UV and normals depending on what face it belongs to. And since all 3 arrays run alongside each other (indexed by the same ID in the first IDXA), PNTA has to be extended accordingly.		:Regardless of technical issues, they have to duplicate PNTA entries because a vertex can have different UV and normals depending on what face it belongs to. And since all 3 arrays run alongside each other (indexed by the same ID in the first IDXA), PNTA has to be extended accordingly.
	::[[User:Geyser\|geyser]] 19:30, 30 January 2007 (CET)		::[[User:Geyser\|geyser]] 19:30, 30 January 2007 (CET)

			{{OBD}}

Iritscen: original ssg site is down, not Archived, and I don't know what the equivalent links would be, if any, under ssg.oni2.net

2020-03-29T17:27:08Z

original ssg site is down, not Archived, and I don't know what the equivalent links would be, if any, under ssg.oni2.net

Paradox-01: better link

2017-07-16T16:47:59Z

better link

← Older revision		Revision as of 16:47, 16 July 2017
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	::[[User:Geyser\|geyser]] 19:30, 30 January 2007 (CET)		::[[User:Geyser\|geyser]] 19:30, 30 January 2007 (CET)
	::As for the first VCRA: they are vertex normals (basically, averages of the face normals for the adjacent faces). Normalized.		::As for the first VCRA: they are vertex normals (basically, averages of the face normals for the adjacent faces). Normalized.
	:::Oni (OpenGL) uses them for [~~http~~:~~//en.wikipedia.org/wiki/~~Gouraud_shading Gouraud shading].		:::Oni (OpenGL) uses them for [[wikipedia:Gouraud_shading\|Gouraud shading]].
	::;geyser		::;geyser
	:I'm not sure why so many entries are necessary for the PNTA and the first VCRA. To fix vertex lighting?		:I'm not sure why so many entries are necessary for the PNTA and the first VCRA. To fix vertex lighting?

Geyser: M3GM talk moved here

2007-01-30T18:30:41Z

M3GM talk moved here

New page

Incoming from my talk page. Could do with further trimming once the talk is over.
==M3GM==
:First off, a little rant: try to be more careful with the "done" label on Oni Stuff
::(how can you say M3GM is "done" when you have no idea how the VCRA and IDXA are interpreted in that specific case?)
::;geyser
:M3GM contains only links, so it's done. (I don't look to the hierarchy.)
:VCRA and IDXA ==> [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm Any ideas?]
::;ssg
:IDXA and VCRA (and PNTA, even) are generic: they get interpreted in different ways depending on where they're linked to ''from''.
:In particular, the parsing of the first IDXA is non-trivial and highly specific (see the source for Pierre's OniRip).
::(when you say "That's clear.", could you be more precise? are you sure you understand what face goes where and why?)
:Actually, the high bit denotes, ''in this specific case'', the first vertex of a "strip": they're ''not'' triangles.
::(and in other cases, the high bit will mean something completely different)
:Knowledge about IDXA etc should be detailed specifically to the resources that link to them: for example, the M3GM.
::Look at your [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm werte.htm] again. See how all the generic sub-resources of an M3GM are connected? They simply don't make the same sense when considered out of the M3GM's context...
:That's why I say M3GM is not "done": because [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm THIS] is missing knowledge relative to ''M3GM'', ''not'' VCRA or IDXA...
::Sometimes the hierarchy is crucial, i.e., you have to consider a file together with its children/parents.
:M3GM: Again, they contain only links, so it's done. I know that there're different IDXA and VCRA files, so they are not done, because there is still no differentiation between the different files.
::;ssg
:Parsing of the VCRA and IDXA is specific to the M3GM and whatever other file they belong to. Their ''meaning'' is specific to the M3GM, in a way.
:Obviously, I don't want to argue about this forever. I'll just detail the format of ''all'' M3GM-specific stuff on the M3GM page and that's it ^^
:One question to you, though. What ''other'' files (apart from the M3GM) use PNTA, TXCA, VCRA and IDXA resources? AKEV? Anything else?
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)
----
:Most of the stuff is as ssg says [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm HERE].
:*PNTA, TXCA, first VCRA: vertex map (XYZ, UV, vertex normals). Vertex normals used for Gouraud shading.
:*Second VCRA: face normals, for flat shading (not sure the engine ever switches from Gouraud to flat) and specular effects.
:*First IDXA: polygon strips. Vertices are listed this way:
0-2-4-6-...-2n
\|\|\|\...\|
1-3-5-...-2n-1
::the oriented faces are (0,1,2), (1,3,2), (2,3,4), (3,5,4) etc
::Strips refer to vertex IDs (those in the PNTA/TXCA/VCRA1). The first vertex of a strip is flagged with a high bit.
:*Second IDXA: normal groups. The triangles (listed in the order in which they appear in strips) are assigned to a face normal (VCRA2).
::[[User:Geyser|geyser]] 00:33, 28 January 2007 (CET)
===PNTA and TXCA and 1st VCRA===
:I'm surprised your page doesn't include a listing of the TXCA. How can you be sure it's irrelevant? (ah, OK, it's parallel to the PNTA...)
==1st IDXA==
:door example: I don't agree with you, that they are "strips".
:Biturn says, that they're triangles and you have to read the first IDXA in this way:
http://www6.fh-eberswalde.de/user/dkriesch/oni/doorcode.gif
:grey = high bit, red = same as the first column, yellow = same as the first row column but first and second value switched
:If you read it step by step (I used Rhino3D), you get this:
http://www6.fh-eberswalde.de/user/dkriesch/oni/door.gif
::;ssg
:That's ''exactly'' what strips look like. I couldn't have illustrated them better myself. Thanks. ^^
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)
:Seriously, Biturn and I/Pierre are saying the same thing. Look at the Rhino3D screenshots again.
:The first 5 faces are all connected and form a strip that wraps around the mesh.
:Same for the next 3, and the next 2, and the last 2 taken separately.
:If I unwrap those strips and make them go left to right with the outside facing you, I get:
a-c-e-g h-j-l m-o q-s t-v
\|\|\| \|\| \|\ \| \|
b-d-f i-k n-p r u
:(I used letters to refer to IDXA elements, to avoid confusion with vertex IDs)
:The triangles are then (a,b,c),(d,c,b),(c,d,e),(f,e,d),(e,f,g),(h,i,j),(k,j,i), etc...
::(compare with Biturn, and with what I said earlier: note that (d,c,b) is the same as (b,d,c))
:::(i.e., swapping 1st and 2nd vertex IDs is the same as swapping ''any'' two vertices! )
:Storing triangles that way (''as'' strips) saves some space (the IDXA has 22 elements instead of 36).
:It requires (at store-time) an algorithm that decomposes the mesh into strips rather than triangles.
:So no, it's not the same thing. "Triangles" stored "in this way" is what we call "strips". OK? ^^
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)
==2nd IDXA==
:The second IDXA contains the normal for every triangle.
::;ssg
:I.e. the ID of a normal stored in the 2nd VCRA.
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)
==2nd VCRA==
:And IMO the normals aren't used for shading, but for the textures, to say to the texture:
::look with your front side to the same direction as the normal.
::;ssg
:The outside and inside of every triangle are already defined in a discrete way by the first IDXA.
::If you look at a triangle, and the vertices cycle counter-clockwise, then it's facing towards you.
:The face normals are redundant of that information. Pierre says they're not used for rendering a priori.
:A very simple way to check is to swap a few IDs in the second IDXA, and see what happens ^^
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)
==1st VCRA==
:I only don't understand why there are 16 points and normals for them.
::;ssg
:Because of vertex shading. I told you before.
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)
::As for the first VCRA: they are vertex normals (basically, averages of the face normals for the adjacent faces). Normalized.
:::Oni (OpenGL) uses them for [http://en.wikipedia.org/wiki/Gouraud_shading Gouraud shading].
::;geyser
:I'm not sure why so many entries are necessary for the PNTA and the first VCRA. To fix vertex lighting?
::Gouraud will only look nice for rather smooth objects, such as a head; err, for Konoko's head, actually, it's rather ugly.
:::And it's totally unadapted for box-shaped objects, which are ''supposed'' to appear square, not smooth.
:I'd expect there to be a flag somewhere that turns Gouraud on and off.
::If there's none, then vertex shading will indeed have to be "fixed" for angular geometry.
:Which means more PNTA and VCRA for a door than "needed" for a smooth "cube"... Almost stupid, but "c'est la vie".
::;geyser
:Regardless of technical issues, they have to duplicate PNTA entries because a vertex can have different UV and normals depending on what face it belongs to. And since all 3 arrays run alongside each other (indexed by the same ID in the first IDXA), PNTA has to be extended accordingly.
::[[User:Geyser|geyser]] 19:30, 30 January 2007 (CET)

← Older revision		Revision as of 17:27, 29 March 2020
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	::;geyser		::;geyser
	:M3GM contains only links, so it's done. (I don't look to the hierarchy.)		:M3GM contains only links, so it's done. (I don't look to the hierarchy.)
	:VCRA and IDXA ==> [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm Any ideas?]		:VCRA and IDXA ==> <nowiki>http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm</nowiki> Any ideas?
	::;ssg		::;ssg
	:IDXA and VCRA (and PNTA, even) are generic: they get interpreted in different ways depending on where they're linked to ''from''.		:IDXA and VCRA (and PNTA, even) are generic: they get interpreted in different ways depending on where they're linked to ''from''.
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	::(and in other cases, the high bit will mean something completely different)		::(and in other cases, the high bit will mean something completely different)
	:Knowledge about IDXA etc should be detailed specifically to the resources that link to them: for example, the M3GM.		:Knowledge about IDXA etc should be detailed specifically to the resources that link to them: for example, the M3GM.
	::Look at your [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm ~~werte.htm]~~ again. See how all the generic sub-resources of an M3GM are connected? They simply don't make the same sense when considered out of the M3GM's context...		::Look at your site <nowiki>http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm</nowiki> again. See how all the generic sub-resources of an M3GM are connected? They simply don't make the same sense when considered out of the M3GM's context...
	:That's why I say M3GM is not "done": because [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm ~~THIS]~~ is missing knowledge relative to ''M3GM'', ''not'' VCRA or IDXA...		:That's why I say M3GM is not "done": because <nowiki>http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm</nowiki> is missing knowledge relative to ''M3GM'', ''not'' VCRA or IDXA...
	::Sometimes the hierarchy is crucial, i.e., you have to consider a file together with its children/parents.		::Sometimes the hierarchy is crucial, i.e., you have to consider a file together with its children/parents.
	:M3GM: Again, they contain only links, so it's done. I know that there're different IDXA and VCRA files, so they are not done, because there is still no differentiation between the different files.		:M3GM: Again, they contain only links, so it's done. I know that there're different IDXA and VCRA files, so they are not done, because there is still no differentiation between the different files.
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	::[[User:Geyser\|geyser]] 19:30, 30 January 2007 (CET)		::[[User:Geyser\|geyser]] 19:30, 30 January 2007 (CET)
	----		----
	:Most of the stuff is as ssg says [http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm ~~HERE]~~.		:Most of the stuff is as ssg says here: <nowiki>http://www6.fh-eberswalde.de/user/dkriesch/oni/werte.htm</nowiki>.
	:*PNTA, TXCA, first VCRA: vertex map (XYZ, UV, vertex normals). Vertex normals used for Gouraud shading.		:*PNTA, TXCA, first VCRA: vertex map (XYZ, UV, vertex normals). Vertex normals used for Gouraud shading.
	:*Second VCRA: face normals, for flat shading (not sure the engine ever switches from Gouraud to flat) and specular effects.		:*Second VCRA: face normals, for flat shading (not sure the engine ever switches from Gouraud to flat) and specular effects.
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	:door example: I don't agree with you, that they are "strips".		:door example: I don't agree with you, that they are "strips".
	:Biturn says, that they're triangles and you have to read the first IDXA in this way:		:Biturn says, that they're triangles and you have to read the first IDXA in this way:
	http://www6.fh-eberswalde.de/user/dkriesch/oni/doorcode.gif		<nowiki>http://www6.fh-eberswalde.de/user/dkriesch/oni/doorcode.gif</nowiki>
	:grey = high bit, red = same as the first column, yellow = same as the first row column but first and second value switched		:grey = high bit, red = same as the first column, yellow = same as the first row column but first and second value switched
	:If you read it step by step (I used Rhino3D), you get this:		:If you read it step by step (I used Rhino3D), you get this:
	http://www6.fh-eberswalde.de/user/dkriesch/oni/door.gif		<nowiki>http://www6.fh-eberswalde.de/user/dkriesch/oni/door.gif</nowiki>
	::;ssg		::;ssg
	:That's ''exactly'' what strips look like. I couldn't have illustrated them better myself. Thanks. ^^		:That's ''exactly'' what strips look like. I couldn't have illustrated them better myself. Thanks. ^^