Hardware T&L -> Not changing vertex arrays?

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5 comments, last by Pav3 22 years, 8 months ago
PLEASE don''t tell me i should or shouldn''t use HW TnL, ot that''s it is useless like in the previous post. please just tell me how am i supposed to do animations if im not supposed to change my vertex arrays? I have a radeon which VERY MUCH supports second gen HW TnL..
**> ATi Rules! nvidia doesn''t...that simple! <**
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why aren''t you supposed to change your vertex array?



How many Microsoft employees does it take to screw in a light bulb?
None, they just declare drakness as a new standard.
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You could use frame-based animation... but that has memory overhead and is only as smooth as the amount of frames you create before-hand. Just make sure all your static stuff gets compiled into vertex arrays, for anything dynamic I''d keep it on your side of the bus.

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- outRider -
Well, you can change your vertex arrays, but you can''t lock them, if they change. This will make you lose performance. It''s rather easy: If a (compiled) vertex array isn''t changed (static), then it can reside in the 3D cards memory, until it gets kicked due to cache trashing. This makes the whole thing faster, since the card can directly access it without having to transfer it over the AGP bus. If you change it, it has to be reuploaded to the 3D card. Depending on how big your array is and how much arrays you have, this can be a very small to very high overhead. Depends on your application.

- AH
also i dont believe anyone said u shouldnt use hardware t+l, i think youve misread the posts
zedzeek : u said i shouldn''t care about whether tnl is hw or not, but why is it in MDK2 without HW tnl the game looks a lot blokier?

anyhow...

so if fir example i have a characters head in an array :
GLfloat headCoords[200][3];

if before i draw it i use glTranslatef on the modelview matrix, does this count as changing it?
**> ATi Rules! nvidia doesn''t...that simple! <**
Pav: Ofcourse you can do anything you want with the modelview (and projection, texture, ...) matrix stacks. You can also change the texture, lighting mode, blend modes... Changing the array just means changing the actual coordinates stored in it (eg. vertices, normals, texcoords, anything you supplied in the first place).

A locked vertex array that you couldn''t even transform wouldn''t be very usefull, would it

- AH

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