perspective in opengl
February 26, 2000 12:50 PM
Hi,
for spellbound who responded to my other post-thanks i got it and the pyramid fully working. Anyways although i can use the function gluPerspective i dont really get it entirly. The field of view parameter is that like the angle of vision from left to right or what?(i basically just id trial and error but i still dont get it) and can someone give me some info on the aspect parameter i know you just divide the width and height but why is that so. the near and far i get. Thanks.
ECKILLER
ECKILLER
122
February 26, 2000 02:50 PM
I''m sorry if I confused you in the other post. Let''s see if I can confuse you some more. 
The fovy parameter to gluPerspective is the angle between the upper and lower frustum sides. (Compare with glFrustum).
The aspect parameter is there because just before the coordinates are converted to screenspace they are normalized in a box going from (-1,-1,-1) to (1,1,1). With aspect set to one this box is stretched to fit the window, which will give a distorted look on all non-square windows.
As it says in MSDN Library: "The aspect ratio that determines the field of view in the x-direction. The aspect ratio is the ratio of x (width) to y (height)."
The fovy parameter to gluPerspective is the angle between the upper and lower frustum sides. (Compare with glFrustum).
The aspect parameter is there because just before the coordinates are converted to screenspace they are normalized in a box going from (-1,-1,-1) to (1,1,1). With aspect set to one this box is stretched to fit the window, which will give a distorted look on all non-square windows.
As it says in MSDN Library: "The aspect ratio that determines the field of view in the x-direction. The aspect ratio is the ratio of x (width) to y (height)."
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