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# camera

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hi, i''m a relatively new to OGL and my problem is Camera... In MSDN, the camre funcs are poorly commented (just descripted), so I''ve read some tuts. But there''s one point I''m still helpless with. when using gluLookAt(eyex,eyey,eyez,centerx,centery,centerz,...) then center... family params mean what? One tutorial (gametutorials.com) noted it as a vector, another (nehe) as the position of the point we look at. What''s the truth? I actually tried to just zoom (move closer and further to the object) and i didn''t work. If it''s a vector, should it be a normalized vector? And then, I have problems moving my camera around (just stays at the center of the scene (0,0,0). Could you help me?

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the 3rd set of coords in gluLookAt is the point at which you are looking. thus if you have 0,0,0 as the final set of coords, no matter where you move you will always be looking at the origin.

it makes more sense to me to store the view coords as a vector in my objects (makes rotation of view easier) so when i do gluLookAT i always enter the 3rd set of coords as view.x - pos.x, ....

but they are defintiely the COORDS you are looking at, not a vector representing your view direction.

-me

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Palidine: I think you have your order messed up. The third set of coordinates is the "up" location (normally 0,1,0). The first set is the location, and the second set is what you are looking at.

gluLookAt(eyex, eyey, eyez, centerx, centery, centerz, upx, upy, upz)

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Ummm, okay, so i have two points, eyex, eyey, eyez, lookingtox, lookingtoy, lookingtoz. I''ve tried to make a overhead game and wanted to move the camera as the main character moves... I set the camera view like

  glLookAt(hero_x,hero_y,10, //looking from a distance of 10 units         hero_x,hero_y,0,  //looking at the hero (his Z coors always equal to 0, a 2d game         0,1,0); //just the up vector

now I would expect the camera to zoom out if I change the 10 in the first line (eyez) from 10 to ie. 20 and to zoom in when changing it to ie. 5. That doesn''t happen (. Even if I change the hero_x, hero_y coords (having a triangle drawn at 0,0,0 to see the center of my scene), it''s still in the center of the viewport... why? I, again, would expect it to "move" a little bit out of the center... I''ve prolly misunderstood some key thing. What''s that?

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Are you in ortho mode? (If so, the size of everything would not change no matter how far away it is).

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yes I''m because I don''t know how to change the viewport width and height (in units) in any other way than glOrtho, i tried some glFrustum, but I wasn''t succesfull.