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jessica
10-27-2003, 09:19 AM
I wanted to render a section of a sphere and then find the normals at every point on the shape. I want the radius of the sphere to be 10cm. Can anybody tell me how to do that in opengl?

Zengar
10-27-2003, 09:29 AM
Normal in (x, y, z) is the normalized radius direction. For point (x, y, z) e S it would be then

((x - x0), (y - y0), (z - z0))/R where
(x0, y0, z0) is the center of the sphere.

You should have post it in the beginners forum thought... http://www.opengl.org/discussion_boards/ubb/biggrin.gif

PanzerSchreck
10-27-2003, 09:47 AM
1.) There is no measurement like 10cm or 10" or 10 meteres in OpenGl...
2.) OpenGL won't do this for you.You'll have to write an own algorithm to calculate the vertexdata for the section of a sphere (not that hard.I did it some time ago) and then you'll also have to calculate the normals on your own.
3.) I hate crossposting...

3k0j
10-27-2003, 10:46 AM
I think the following advice should be put in FAQ, when it is created (you know, the OpenGL site is being restructured) :

If you'd like to post offtopic/too-general/too-beginner question here and still get some useful help instead of only getting bashed/insulted/patronised, then do post using a nick suggesting that you are a female.

http://www.opengl.org/discussion_boards/ubb/biggrin.gif http://www.opengl.org/discussion_boards/ubb/biggrin.gif http://www.opengl.org/discussion_boards/ubb/biggrin.gif http://www.opengl.org/discussion_boards/ubb/biggrin.gif

Zengar
10-27-2003, 10:51 AM
How funny

jessica
10-27-2003, 10:52 AM
sorry. I posted on beginner too but i thought some people might not look at that list if theyre advanced... :S

thanks for all the suggestions.

SirKnight
10-27-2003, 11:49 AM
You can always generate a sphere using spherical coordinates. If you understand this coordinate system, generating verticies for a sphere is very easy. Then next part is then creating the winding. After that is all said and done, generating a normal (for each triangle) is just a simple normalize( cross( V1 - V0, V2 - V0 ) ).

-SirKnight

[This message has been edited by SirKnight (edited 10-27-2003).]

knackered
10-27-2003, 12:49 PM
Jessica, mmm, that's a nice name.
Where you from Jessica?
http://www.opengl.org/discussion_boards/ubb/smile.gif

Jan
10-27-2003, 02:04 PM
Originally posted by knackered:
Jessica, mmm, that's a nice name.
Where you from Jessica?
http://www.opengl.org/discussion_boards/ubb/smile.gif

nerd

SirKnight
10-27-2003, 02:28 PM
Originally posted by Jan2000:
nerd

Who isn't on this board? http://www.opengl.org/discussion_boards/ubb/biggrin.gif

-SirKnight

rgpc
10-27-2003, 02:56 PM
I'm not.

Live long and prosper... http://www.opengl.org/discussion_boards/ubb/biggrin.gif

knackered
10-28-2003, 05:15 AM
Originally posted by Jan2000:
nerd

I take it you missed the irony?
Thought so...

Coconut
10-28-2003, 06:06 AM
Don't you think Jessica could have gotten the answer for her assignment from the dude sitting next to her without harrassments from you guys?

[This message has been edited by Coconut (edited 10-28-2003).]

V-man
10-28-2003, 10:57 AM
http://www.opengl.org/discussion_boards/ubb/F
orum2/HTML/014273.html

"excuse me ! who is Silvia , I did not get your point" <-- playing dumb

"Let me introduce you to Silvia: " <-- heating the room

"why did not I tell you the truth at the beginning " <-- gives up and admits

case closed!

Elixer
10-28-2003, 11:19 AM
Originally posted by knackered:
I take it you missed the irony?
Thought so...

How ironic he missed the irony.

Let see, a .26mm dot pitch monitor would make 10cm be ... Knackered can figure this out. http://www.opengl.org/discussion_boards/ubb/wink.gif

p.s, ... err... forget it... I must be dead tired. http://www.opengl.org/discussion_boards/ubb/biggrin.gif

jessica
10-29-2003, 08:09 PM
Thanks for the replies. I just am having trouble with the rendering.. I know the equation of a sphere. But I dont know exactly how to set all the vertices .. Does anyone have a pointer to an example?

Thanks again, and Im sorry for all the commotion i caused http://www.opengl.org/discussion_boards/ubb/frown.gif

SirKnight
10-30-2003, 06:36 AM
For generating the vertices for a sphere, I think these equations will be more helpful. http://www.math.montana.edu/frankw/ccp/multiworld/multipleIVP/spherical/body.htm

-SirKnight

SirKnight
10-30-2003, 06:46 AM
This may not be all you need or the best but this code snippet should get you started. It will generate the vertices for a sphere, but you still need to compute the winding and everything.

vec3_t GetVertex( float rho, float phi, float theta )
{
vec3_t v;

v[0] = rho * sin( phi ) * cos( theta );
v[1] = rho * sin( phi ) * sin( theta );
v[2] = rho * cos( phi );

return v;
}

int i = 0;

for( float theta = 0.0f; theta < 2*PI; theta += 0.01f ) // play with the 0.01 if it's not good enough
{
for( float phi = 0.0f; phi < PI; phi += 0.01 )
{
SphereVerts[i++] = GetVertex( rho, phi, theta );
}
}

-SirKnight

jessica
10-30-2003, 11:31 AM
thanks sir knight.. just a question - what is sphereverts? and 3D array?

thanks

SirKnight
10-30-2003, 02:15 PM
Ah geeze I forgot to define that, sorry. SphereVerts is just an array of vec3_t. And obviously vec3_t is just "typedef float vec3_t[3];" Now to determine the size of SphereVerts can be done in a few ways. One way is to figure out how many iterations each loop there makes and multiply those two numbers together. That number will be the size SphereVerts needs to be. So lets say that the outer loop makes 628 iterations and the inner loop makes 314 iterations. Then SphereVerts will be defined as "vec3_t SphereVerts[628*314];" I figured those numbers out by dividing 2*PI by 0.01 and dividing PI also by 0.01.

You could even put each vertex made in a linked list, then once that is done check the variable that holds the number of nodes in your linked list class and take that to allocate the SphereVerts array then copy all verts from the list to the array. I would probably not do this but it is one other solution.

Now of course there is still more work to be done than this. That code snippet just generates vertices but no information about winding or anything else is present. But at least the vertices are there to have something to work with.

-SirKnight

[This message has been edited by SirKnight (edited 10-30-2003).]

jessica
10-30-2003, 02:21 PM
Thankyou so much Sir Knight. I now got the sphere displayed using glPoints,but can i get justthe top section somehow? less than half of it

thank you again
jess

SirKnight
10-30-2003, 03:39 PM
Ok so I assume you want only the top hemisphere. Ok to do that is limit the angle phi to a smaller range. Phi is the angle from the top pole of the sphere to the bottom pole, so obviously this is PI radians (or 180 degrees). Since you only want the top hemisphere, phi needs to be limited to [0,PI/2]. So change the for loop that has phi in it to this:

for( float phi = 0.0f; phi < PI/2; phi += 0.01f )

-SirKnight

SirKnight
10-30-2003, 03:49 PM
Alright I just found a link I had saved a long time ago about generating spheres. The coordinate system they use is Polar coordinates extended to 3D. I used the spherical coordinate system because that is always what comes to my mind first when I think of spheres. So using Polar coordinates instead of spherical can save you three multiplies per vertex creation. Of course this is only usefull if you want a unit sphere, if you need to specify the radius, using spherical coords like I did would still be better. Here is the website with code to generate a sphere with user specified tesselation. http://astronomy.swin.edu.au/~pbourke/modelling/sphere/

-SirKnight

[This message has been edited by SirKnight (edited 10-30-2003).]

10-30-2003, 05:27 PM
you guys are such sphereverts eh heh eh heh..
wow a girl? HERE?! that is just so f'ing cool.

And here we thought only guys can be geeky..

knackered
10-30-2003, 11:11 PM
I may very well change my name to gloria or somesuch if it gives dillusional and obviously long-term single young men such as SirKnight the patience to explain in painstaking detail things like drawing a sphere and using an array, rather than telling me to p*ss off and RTFM. My god, he even apologised for not explaining what SphereVerts was. I could do with someone like that in a DIY plumbing forum at the moment.
Jessica, this is an advanced OpenGL forum - your question is neither advanced nor specifically about OpenGL. It doesn't take a rocket scientist to realise it's an inappropriate place to post your question.

JustHanging
10-31-2003, 12:04 AM
Sorry to interfere guys, but come on... If SirKnight can and wants to help, there's no reason to interfere with your smart ass conclusions.

I'm sorry and surprized to see this kind of attitude here. Yeah, the question was not advanced, but you didn't have to drag the whole sex thing into it. Even worse is attacking those who try to help. Just have to respect Jessica for being so cool about it.

-Ilkka

knackered
10-31-2003, 01:42 AM
Originally posted by JustHanging:
Just have to respect Jessica for being so cool about it.
-Ilkka

Looks like SirKnights got some competition.
The only person bringing 'sex' into this is people like you and SirKnight by being so obviously curtious because the questioner happens to be a woman. Even though it's a woman who's asked a stupid question which if it were a male would have prevoked the usual OT/lame screeches.
What's the matter iikka? Should we be more patient with this poster because she's a girl? Is she very brave for asking a question about computer graphics? It must be sooo complicated for her tiny brain to grasp, we should all gather round and help, even though it's off topic.
You are so patronising it's untrue.

dbugger
10-31-2003, 01:58 AM
Hmmm activate brains and RTFM.

Zengar
10-31-2003, 03:12 AM
If I am allowed to throw my 50 cent in...

I think if someone is posting at OpenGL advanced forum, he should have some good knowledge of programming. Someone with good knowledge of programming would know how to combine the sphere after all. I'm talking neither of sex nor of any sort of discrimination. My opinion is: there are several thinks one can do himself, if he will move his grey cells a bit.

It remains me on my first days on this forum, some two years ago. There was some sort of a guy that was posting to advanced forum but didn't know how to implement trivial sorting(!!!). I don't understand it.

I think OpenGL forum - as every coding forum - should present not sulutions but hints. Damn, I want to learn something! I don't want anyone to post some code to help me: I want someone to direct me to paper where it is explained. The final work must be done with MY brain, or I just - and everyone who ansvered me - waisted my time and learned nothing.

And my dear Jessica, I would be very happy to help you, but I've never rendered spheres by hand, and I think I gave you a good hint about normals - and also abou how the sphere is generated. And sorry if I am to to try writing my own algorithm now. But if you want to see how professionals are rendering spheres http://www.opengl.org/discussion_boards/ubb/smile.gif, download the OpenGL sample implementation of SGI. You would find entire glu source code there - with gluSphere included. By editing only one line(i am not telling you which - you should also LEARN something) you can transform it to gluHemisphere. http://www.opengl.org/discussion_boards/ubb/biggrin.gif Good luck.

With best tralala...

Zengar
10-31-2003, 03:20 AM
Originally posted by knackered:
The only person bringing 'sex' into this is people like you and SirKnight by being so obviously curtious because the questioner happens to be a woman. Even though it's a woman who's asked a stupid question which if it were a male would have prevoked the usual OT/lame screeches.

100% agreed. It's not a descrimination - it's showing of respect to the opponent.

Christian SchÃ¼ler
10-31-2003, 06:36 AM
Ask yourself if you would do the same favor to a guy.

If no, it's supplication.

[This message has been edited by cschueler (edited 10-31-2003).]

3k0j
10-31-2003, 07:18 AM
Looks like I've teased hornet hive...

It wasn't my intention to insult anybody nor to invite anybody to insult anyone else. If I did, sorry about that. I was just Trying To Be Funny, nothing more.

knackered:
While I have found it quite amusing to see how female nicks are able to cause significiantly more compassion and good will here, I don't really think that asking stupid question should be vigorously punished with flames and insults by default (regardless sex). Actually, you seem to confuse stupidity with ignorance. The latter can be cured, the former can't. Imagine yourself 5, 10 or 15 years ago (choose appropriate for your case), and realize how ignorant in CG you were (just like anybody else). But does it mean you were stupid then?

Being ignorant is not a sin nor crime nor assault on your peace of mind (everybody starts as ignorant), so if you see ignorant question posted then we should either try to help to cure the ignorance, or simply don't bother so someone else does it eventually. Just because opportunity to ridicule somebody occasionally opens here, it doesn't mean you supposed to take adventage of it.

BTW, typical noob-question answers like "use search", or "google is your friend" are nothing but just useless offence. Effective using those tools is not as easy as it seems for the person which already knows the subject in question. In practice searching often requires knowledge of right keywords, what is most likely to happen if you are already advanced.

[This message has been edited by 3k0j (edited 10-31-2003).]

SirKnight
10-31-2003, 09:54 AM
First of all, knackered you can KISS MY ****ING ASS!! So don't ever say anything to me again. I don't want to see your **** anymore. I never liked you anyway, I always thought you were a ****ing *******. So go get a life for christs sake.

Ok now, I am helping jessica because her question is easy to me and it takes me hardly any effort. Sure I could have said go to the beginner board and a lot of the time I do say that, but at the same time still try to help a little. It does not matter what gender anyone is for me to help them. I was in a good mood so I felt like helping no matter if the question was on topic or not. I like to help people, so ****ing what? If jessica had been a guy, I would have helped in the EXACT SAME WAY. I just felt like helping. Sure off topic posts can annoy me, but it also annoys me to see someone try to do something and no one will be nice enough to help. They just act like a bunch of *******s. It's like "ohh ya im so advanced and smart, I have such a big damn ego that I wont help any one else, I never was in their situation, no sir."

And why would I get all crazy like a typical nerd and be like, OMFG A GIRL HHEHEEHHEHEHEHEHEHE. I won't. Period. I have no problems with the opposite sex like I'm sure a lot of people in here do (from how they're acting now). I'm actually involved with someone right now too. See, I have no problems there. So why would I get all crazy that a girl comes around? I absolutely won't, I'm no dork.

So to any one else here talking crap, SUCK ME!

-SirKnight

jessica
10-31-2003, 10:42 AM
Hi everyone

I apologize for asking such an ignorant question, but I thought that the gl forums are a place where one can find help when stuck and want to ask someone that knows more than you. After all, havent we all asked someone else a "dumb question" when first starting out with something?

Knackered, I am sorry that I caused such an inconvience to you in that you had to click on an extra post just to find a "woman who's asked a stupid question".I agree that posting on the advanced list wasnt such a hot idea, but the reason I posted here was because I thought that I might get help more readily since it would not be as difficult a problem for someone who is a bit more advanced than a beginner. Being a beginner myself, I was not sure how hard the question was anyway. Yea, i guess it doesnt take a rocket scientist to figure this out, but I really didnt think that people would be so mean about it.

Thank you to those of you who have helped me and especially to Sir Knight who was bashed because he offered his help.

Perhaps next time I should pretend I am male and post to the beginners list so that I dont cause such a big deal.

Jess

knackered
10-31-2003, 12:06 PM
Don't "have a cow", SirKnight. Heard the expression "touched a nerve"?
Jessica, I don't really care if your question is on topic or not - but the people who are helping you most certainly do care, but choose to adopt a different approach seeing as you're a female. I find this quite distasteful. As indeed you should, if you're in any way emancipated.

gator
10-31-2003, 12:43 PM
Perhaps next time I should pretend I am male and post to the beginners list so that I dont cause such a big deal.

99% percent chance says you already are. That's just my opinion.

SirKnight
10-31-2003, 12:50 PM
Thank you to those of you who have helped me and especially to Sir Knight who was bashed because he offered his help.

Sure np. You know, this is the first time I have been bashed for helping someone ON A HELP AND DISCUSSION BOARD! Anyone see the irony in this? I'm really suprised at some people here, this has changed a lot for me. I mean I come here on my own free will to offer my knowledge to others so they can benefit from what I have learned and I take fire from it.

I just hope SOME PEOPLE realize that when I help someone, that their gender has nothing at all to do with it. If they continue to be that thick about it and not wake up to reality, then to hell with them I say!

BTW, jessica, don't worry much about what some have said here, it don't mean nothin'. As well they can continue to think/talk crap about me now, but I don't care now. It doesn't mean a damn thing. http://www.opengl.org/discussion_boards/ubb/biggrin.gif

-SirKnight

newt
10-31-2003, 12:55 PM
She got what she wanted didn't she ?

It's what women do. And they usually get it at the expense of the nearest man.

"Oh. I'm such a flippertygibbet, I just can't think how to render half a sphere - let alone a WHOLE one."

"Nonsense my dear, I'll write your algorithm for you !"

"Oh, brave Sir Knight, you truly have saved me, in spite of the derision of your peers (horrid though they are)."

Whatever.

SirKnight
10-31-2003, 12:56 PM
JustHanging, thanks for being one of the very few on my side that realizes what others have said here is ridiculous and uncalled for. Just as you are, i'm suprised to see this kind of attitude here. This board has gone downhill with the quickness.

EDIT: And to those who brought the whole gender thing into this and continue to do so, it's time you grow up and become MEN. This kind of behavior is what teenagers going through puberty do. Very very immature.

-SirKnight

[This message has been edited by SirKnight (edited 10-31-2003).]

gator
10-31-2003, 01:00 PM
Wow, some people are so guillable. Whatever jerks your chain, imho.

Maybe I should post under female name, and start posting beginner questions
in the advanced forum? HotJenni18? Everyone would drooool over me.

newt
10-31-2003, 01:01 PM
I went through puberty a LOOONNNG time ago.

It's my intention to share the benefit of my
experience, just like you ;o)

newt
10-31-2003, 01:03 PM
Hey HotJenni18 want to come over and see my
renderings ?

Elixer
10-31-2003, 01:25 PM
Originally posted by jessica:
[snip]
I agree that posting on the advanced list wasnt such a hot idea, but the reason I posted here was because I thought that I might get help more readily since it would not be as difficult a problem for someone who is a bit more advanced than a beginner. Being a beginner myself, I was not sure how hard the question was anyway. Yea, i guess it doesnt take a rocket scientist to figure this out, but I really didnt think that people would be so mean about it.
[snip]

The problem with the logic is why have a beginner forum at all then?
If you frequent almost any forums, you usually know etiquette, and what to try first (google, or some other search engine, then search groups (instead of web pages, like usenet feeds) and so on).
That is why most people get mad, they are sick of reading n00bish questions in 'advanced' forums.
Having said that, we were all indeed n00bs once, and we have all made mistakes. We usually learn from them though, although that might not come across in some of the posts you see.

Oh, and for the record, you would have gotten the same reply from me if you were a guy/girl/llama or troll.

Then again, this really wouldn't happen if we had a moderator on this forum.

jessica
10-31-2003, 01:44 PM
Ok. Point taken. I will learn from my mistakes. Thank you.

Btw..not that it should matter, but for some of you immature boys, why do you have trouble believing that a girl could post a question?? It shouldnt matter anyway but its not so nice to make accusations that Im lying.

jess.

Elixer
10-31-2003, 01:50 PM
Originally posted by jessica:
Ok. Point taken. I will learn from my mistakes. Thank you.

Btw..not that it should matter, but for some of you immature boys, why do you have trouble believing that a girl could post a question?? It shouldnt matter anyway but its not so nice to make accusations that Im lying.

jess.

Poor choice of words, what makes you think the poster(s) you are talking about are indeed guys? You got a crystal ball or something? If you do got a crystall ball, can you give me the PS code for it? Thanks! http://www.opengl.org/discussion_boards/ubb/wink.gif

Alice
10-31-2003, 02:24 PM
Originally posted by jessica:
Ok. Point taken. I will learn from my mistakes. Thank you.

Btw..not that it should matter, but for some of you immature boys, why do you have trouble believing that a girl could post a question?? It shouldnt matter anyway but its not so nice to make accusations that Im lying.

jess.

Yeah, boys are really mean to us girls around here http://www.opengl.org/discussion_boards/ubb/frown.gif especially knackered.
Guys like him are the reason I'm a lesbian nowadays.

Ysaneya
10-31-2003, 02:59 PM
Looks like SirKnights got some competition.
The only person bringing 'sex' into this is people like you and SirKnight by being so obviously curtious because the questioner happens to be a woman.

I hate to jump into that kind of... discussion. But after rereading the first replies, YOU started to bring sex into this with your completely off-topic, sexist and useless post. May i refresh your memory:

Jessica, mmm, that's a nice name.
Where you from Jessica?

Up to that point, SirKnight's were 100% on-topic and never raised the sex issue.

I'm not trying to flame you, but maybe you should calm and look again at the flow of events that lead to this flame war ? You're certainly not stranger to it.

Y.

Zengar
10-31-2003, 03:52 PM
Originally posted by jessica:
Btw..not that it should matter, but for some of you immature boys, why do you have trouble believing that a girl could post a question?? It shouldnt matter anyway but its not so nice to make accusations that Im lying.

Maybe knackered has got some problem about this. I don't: I don't care if you are a boy or a girl - I don't know you either http://www.opengl.org/discussion_boards/ubb/biggrin.gif.

Back to on-topic: have you managed to do the hemisphere? &)

This forum is becoming uncontrollable I fear. I beg everyone stop this stupid and useless discussion - moral games always made me sick.

Zengar
10-31-2003, 03:55 PM
Ysaneya is right.

Wanted to point this out.

jessica
10-31-2003, 08:59 PM
no i didnt manage to do it yet. http://www.opengl.org/discussion_boards/ubb/frown.gif
Im a stupid newbie girl.

dorbie
11-01-2003, 01:58 AM
To draw a sphere I like to start with a cube around the origin, You subdivide the cube faces into many polygons. Normalize the vertices onto the surface of a unit radius sphere by dividing them by their distance from the origin. These vertex locations that represent points on a unit sphere surface are then also the normals (for a unit radius sphere around the origin the vertices are also the surface normals).

You can then scale and translate the sphere to your required location and size after copying the normals to a different array. This sphere will be much better behaved at the poles but more difficult to texture without artifacts if that's your ultimate intent.

JustHanging
11-01-2003, 06:19 AM
Only because I was directly spoken to:

1. It's Ilkka, not Iikka

2. I don't do the "OT/lame screeches" as you put it. I just ingore questions if I don't feel like answering, exactly like I did now until you got really out of line. Now I remember I did this once to you, but I've already apologised and explained that.

-Ilkka

jessica
11-01-2003, 10:59 PM
Sir Knight, if you are still reading this post, could you please tell me what im doing wrong --I put in the following code, but I dont get a hemisphere..DO you know where i could be going wrong?
Thank you so sooo much.

Jess

void DrawGLScene(){
int x, y;
glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);
for(i=0; i <maxtheta; i++){
theta+=0.01f;
for(j=0; j<maxphi/2; j++){
phi+=0.01f;
spherePoints[i][j][0]=rho*sin(phi)*cos(theta);
spherePoints[i][j][1]=rho*sin(phi)*sin(theta);
spherePoints[i][j][2]=rho*cos(phi);
}
}
glBegin(GL_POINTS);
for (x=0; x<M; x++) {
for (y=0; y<N; y++) {
glColor3f(1.0, 0.0, 0.0);
glVertex3f(spherePoints[x][y][0], spherePoints[x][y][1],spherePoints[x][y][2]);
}
}
glEnd();
glutSwapBuffers();
}

knackered
11-02-2003, 06:03 AM
Originally posted by Ysaneya:
[B] Up to that point, SirKnight's were 100% on-topic and never raised the sex issue.
[B]

By christ this has become quite controversial.
I guess you didn't realise what I meant. Maybe english isn't your first language. What I meant was by answering such a bollox question in such an enthusiastic way, he was being sexist - there can simply be no other explaination. Simple as that.

SirKnight
11-02-2003, 07:22 AM
I think the problem is in your for loops. I think it would be better if you had them as:

for( float theta = 0.0f theta < 2*PI; theta += 0.01 )

and

for( float phi = 0.0f; phi < PI/2; phi += 0.01 )

Your loops may not be iterating enough. With the loops like I have them, they will.

-SirKnight

SirKnight
11-02-2003, 07:26 AM
I'd like to say that Ysaneya is 100% correct. To think anything other would be just stupid.

-SirKnight

SirKnight
11-02-2003, 07:29 AM
Jessica, dorbie's method he said he uses is also a very good method that you should also try out sometime to see which way works better for you. The method he describes is in that web site I posted that talked about using polar coordinates and had a code example. But either method works.

-SirKnight

Ysaneya
11-02-2003, 07:30 AM
What I meant was by answering such a bollox question in such an enthusiastic way, he was being sexist - there can simply be no other explaination.

You're right that English is not my first language; and i don't know you (or SirKnight) at all except from what i'm reading from these very forums. But from a 3rd-person point of view (me), i have absolutely no idea how you can, from his reply, deduct that it was over-enthusiastic and sexist:

You can always generate a sphere using spherical coordinates. If you understand this coordinate system, generating verticies for a sphere is very easy. Then next part is then creating the winding. After that is all said and done, generating a normal (for each triangle) is just a simple normalize( cross( V1 - V0, V2 - V0 ) ).

But you're right, it has become controversial so i will not continue on this topic.

Y.

jessica
11-02-2003, 10:11 AM
Thank you Sir Knight, it worked!! http://www.opengl.org/discussion_boards/ubb/smile.gif

Jess

knackered
11-02-2003, 11:19 PM
Of course it worked, it's called logic.
Right, next question sweetheart... (PTO on your exam paper means Please Turn Over, by the way)...

romeo_64
11-03-2003, 02:46 AM
I haven't been to opengl for months but
omg, advance forum has improved! now it's even more entertaining than soap

great job! keep it up