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ndhb

Lesson 09 wording

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First of all, thank you. I really enjoy the NeHe Tutorial on OpenGL so far. I'm currently at Lesson 09 but I find the example with the spinning room slightly confussing: "The first thing we do is spin the scene on the x axis. If we spin 90 degrees..." Aren't we rotating the scene on the y-axis to move -x "into the screen"? In the following paragraph of the lesson it continues: "because we've rotated on the y plane" My question is this, what is the difference between spinning the scene on the x axis and rotating on the y plane. If there is no difference how does glRotatef(tilt,1.0f,0.0f,0.0f) achieve a rotation on the y plane when the 1.0 coordinate is the x-parameter? Nicolai de Haan Copenhagen, Denmark

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It's a bit hard to understand i know.
And there is probobly other ways of doing this, but this one is pretty good though, im shure you could do without the tilt rotation if you just fiddle a little with the coordinates.

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Guest Anonymous Poster
Yeah, i got the same question and was surprised that someone wrote nearly the same I would probably have done :)
The rotation is obviously (if u launched the prog) 'around' the x-axis. But if it is so, the x-axis is the only one that does _not_ move. than i have to correct nehe (if i had his e-mail .. hmm): There is no exact y-plane, it is uncertain. imo the 'y,z-plane' would be better; and a rotation on the y,z-plane is the same like one _around_ the x-axis.
and the procedure 'glrotatef' does rotate by [1.param] degrees around a line (axis), defined by the origin and the second point defined by [params 2-4] , so in the example around the x-axis.
I hope this helps you, and more than lc_overlord's post, who only admits thats little hard to understand but doesnt do a try to explain...

ps: Does anyone know where the 'impressum' (contact, etc..) of nehe's production site is (maybe i still overlooked it, but i searched some time...); or simply his e-mail?

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So, now i am registered, I did the last 'anonymus' post (thought I though could enter a name, but...

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