| |
| |
| |
|
Page: 1 2 3 4
Comments:
<0> hi ... anyone could me answer a short question about nurbs ?
<0> i'm trying to find out about the usage of the knots... how do they manipulate ?
<1> hey its Aren :D
<1> welcome to efnet hehehe
<2> Hey it's me!
<3> :)
<2> man all these math terms are giving me a headspin
<4> <Aren__> for one I don't understand it's definition
<4> <Aren__> q=<w,x,y,z> = w+ xi +yj +zk
<4> <Aren__> where it's often written as q= s+ V
<4> <Aren__> where V is a vector, and s is the scalar corresponding to the W component
<4> <Aren__> then it goes on to say the ijk are imaginary components
<4> seems like a reasonable question
<2> hehe sorry for my ignorance
<2> but maths/computer science/any kind of science isn't my major
<4> does this help http://en.wikipedia.org/wiki/Quaternion ?
<4> sure is confusing to look at thats for sure
<4> nehe is frownd upon for some reason around here but http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=Quaternion_Camera_Cl***
<4> StarG did you ever figure out your knots ?
<4> if you want to explain your question a bit better we might be able to help
<5> Is using using 6 quads noticeably diffrent for rendering a cube then something like a quad strip to render it all at once?
<4> good question but I'de say no just slower
<5> Humm, what would be the best way to test it?
<5> Render 10000 cubes onscreen, with one way, then the other?
<6> any news if sony is realesing more than just framebuffer access to it's ps3?
<7> Kunnis, the fastest way for 10k cubes would be triangles through one glDrawElements call ; vertices being stored in a VBO's video memory
<7> For a couple cubes, don't even think about it :)
<5> I was wondering if there is a major speed diff between rendering 6 quads, or if using a quad strip would be faster...
<5> I was thinking that would be a reasonable test.
<5> Or there may be no diff
<7> Either way, the drivers would have to break up into triangles prior to rendering
<7> And there are far more signifiant factors really
<5> Okay, so that's a vote for no real diff.
<5> I dunno... I was wondering if really smart people could use it to predict what doesn't need to be rendered.
<7> Strips mostly exist to ease reuse of transformed vertices by the hardware, as do glDrawElements
<5> does switching to glDrawElements improve over just using glVertex
<7> Yes, definitely
<7> Later on, you could look into Vertex Buffer Objects to store vertex attributes in video/AGP memory
<5> Does the site in the topic have lists of basic optimizations?
<7> Hum, that version of the redbook cover the basics, not VBOs and so on
<7> Get used to vertex arrays ( glDrawElements ), switching over to VBOs will be really easy from there
<5> Thanks
<5> I'm crash coursing in some code that was just open sourced and it needs some help
<5> they use glVertex heavily.
<5> they barely use glDrawElements
<7> When the count of vertices is very low, Begin/End can do
<5> The same objects tend to be rendered over and over and over again.
<5> most objects are stationary, but they all tend to have textures
<7> How many vertices per frame are you dealing with?
<5> I don't honestly know. It's Second Life...
<5> Well they are very texture-driven. Honestly they have more bad code doing stupid stuff like file maintance. I shaved ~1/2 second off the inital load time with a day's worth of work.
<5> Just replaced some custom templates with the correct std::vector && std::sort templates.
<5> Almost knocked the entire method off the profiler.
<7> I never saw Half Life, but I'm now guessing it's not quite Quake 4 quality
<7> Ooos, Second Life rather
<5> Want to dig into Second Life and help fix it up?
<7> No thanks :), I'm busy enough already
<5> It's honestly very neat code.
<5> They are more network bound then anything else right now
<5> their network IO code is a MESS
<7> So is their rendering code from what I have just heard
<5> They decided to use UDP for everything. They relaized that was a mistake, and they are starting to fix it.
<5> Their rendering code just isn't complex. It functions and feeds frames to me at ~25fps.... though it should be higher.
<5> I can do 30fps on WoW normally.
<5> And I bet wow is a lot higher poly count.
<7> It's still poor code, by people who didn't seem to know rasterization graphics
<5> Dig into a section, and fix it. That's what I did to a small slice of their filesystem
<5> Then you get to write all the fun 3d parts, with none of the h***le of the backends that hold it together.
<5> My strengths are a bit more towards networking... Too bad I can't dig into their server. They just need to replace part of the server code. Their binary transfer protocol is crap.
<5> well... not crap, but not the way i'd like it. I see it as having problems scaling.
<7> I'm sure OpenGL programmers will pop up to fix the game, ***uming it has a good players base
<5> It's got some FOSS support, it's slowly building... but someone has to step up.
<5> So what does push & pop matrix do?
<5> or do I need to rtfm?
<8> the redbook explains it pretty well
<9> glPush/PopMatrix pushes and pops the current matrix stack.
<9> Do you know what a stack is?
<9> A LIFO queue
<9> last in, first out
<9> So every time you push the stack, you get a fresh copy of the current matrix.
<9> So that new transformations won't be global.
<10> Second life is open source code?
<5> That I understand, you use it to save the matrix, then you can change it and restore it. But what does the matrix do?
<9> Then, when you are finished, you pop again.
<5> Yeah, LL Open Sourced the client about 2 weeks ago
<10> wow, didn't know that
<9> You use OpenGL and don't know what a matrix is.. ?
<5> you can /join #opensl, they have about 4 devs that hang out there.
<10> I've never use SL
<5> I know what a matrix is, I don't know what it does in this case.
<10> Heard about it though
<9> *shrug*
<5> Yeah, there's a wiki with complete download and build directions. They take patches.
<5> What is the matrix storing?
<10> Do you know what licence? GPL?
<9> OpenGL uses matrices for transformations. Like 99.999% of other graphic APIs do.
<7> Kunnis, vertices are transformed by matrices prior to rasterization
<5> It's dual licensed, GPL with a FOSS exception + propriatary.
<10> Hmm, well I don't know what that means really.
<10> But it should be pretty in a couple of years
<9> You are quite in a hurry if you start with OpenGL and don't know what a goddamn matrix is used for in computer graphics..
<10> *pretty interesting
<9> Sorry for telling.
<5> It's gpl.. except for the parts they can't gpl because it's built against non-opensource libs.
<5> I know what a matrix is, but I didn't know if this was the transform matrix, or some other matrix I have no idea about.
<10> ah
<10> Good for them
<10> I'm suprised they would do it
<10> I wouldn't have done it ;-)
<5> Ah, and so glLoadIdentity() basically zeros the matrix out?
<7> The identity matrix isn't quite made of zeroes
<9> Kunnis: The identity in matrix terms is the value "1"
<9> Not zero.
<5> {{1,0,0}{0,1,0}{0,0,1}}'s the matrix out?
<7> It's 4x4, but yes
<5> Right... alpha.
<9> Err.. alpha? What?
<7> Alpha? :) The 'W' would be the translation component, mostly
<5> No, it can't be alpha... that's color... the matrix describes position.
<9> 4D vectors, and the forth row for translation.
<5> Right, vectors. I'm too used to thinking 3d.
<9> Kunnis: No, the matrix describes a coordination system.
<5> That makes sense in a mad sort of way.
<9> Now, read instead of guessing :)
<9> http://www.gamedev.net/reference/articles/article1691.asp
<5> NOOO NOT is> That makes sense in a mad sort of way.
<5> <Madsy
<5> ack.
<5> NOOO NOT Quaternions!
<9> Then skip quaternions. It explains both.
<9> But knowing how to use matrices is kind of essensial.
<9> At least if you haven't done any computer graphics prior to OpenGL or DirectX.
<9> Which seems to be the trend nowadays..
<5> I've done a little a long time ago. 13h forever!
<9> What happened to good old software rendering? ;(
<9> Well.. ***embly is quite overkill.
<9> But at least direct draw or GDI
<7> And... there's ***embly ;)
<9> Maloeran: I hope you've profiled it first :)
<9> Nothing is worse than using 2 weeks for optimalization, and then get a 1% speed increase.
<5> What are the limits of using something like opengl, or is it just a matter of speed?
<7> Limits in what sense?
<5> I dunno. Anything you can't do, or is hard to do in opengl that's easier in a lower level language?
<9> OpenGL isn't a language. It is a standard.
<7> It isn't a language, it's just a graphic library
<7> But it's rasterization, so it will never get photo-realistic ; a fundamental limitation
<9> You have somehow limitations on per pixel control, but there are other methods you can use instead.
Return to
#opengl
or
Go to some related
logs:
#eggtcl
unactivate xp
terje unixhelp
#beginner
#mirc
exgirls friends
ccbill ripper
#politics
#worldcup
#nhl
|
|