about gluPerspective

gluPerspective(fovy, aspect, zNear, zFar)

the function takes 4 parameters and I don’t

quite understand what the first parameter


according to the GLU API specification

the first parameter defines "the field-of-

view angle(in degrees) in the y direction".

what does it mean by “angle in the y direction”?

how’s the angle measured?

The angle is defined in degrees and specifies the angle between the upper and the lower clipping plane.

hi iori,
well just like michael said,
if your world or object Y-position is bigger than the upper clipping plane or less than the lower clipping plane,then
your world and object will not be visible.