Setting near plane in OpenGL

Question

i have implemented first person camera in OpenGL, but when i get closer to an object it starts to disappear, so i want to set near plane close to zero so i could get closer to the objects. So if anybody can tell me what is the best way to do that. Thank you.

Answer 1

Other responses focus on using glut. Glut is not recommended for professional, or even modern, development, and the OP says nothing about using glut - just OpenGL. So, I'll chime in:

A little background

zNear, the distance from the origin to the near clip plane, is one of the parameters used to build the projection matrix:

Projection Matrix

Where

SYMBOL  MEANING                   TYPICAL VALUE
------  --------------           -------------
fov     vertical field of view   45 – 90 degrees
aspect  Aspect ratio             around 1.8 (frame buffer Width / Height)
znear   near clip plane          +1
zfar    far clip plane.          10

SYMBOL      MEANING                          FORMULA
----------  -------------------------------  --------------
halfHeight  half of frustum height at znear  znear∗tan(fov/2)
halfWidth   half of frustum width at znear   halfHeight×aspect
depth       depth of view frustum            zfar−znear

(More nicely-formatted version on http://davidlively.com/programming/graphics/opengl-matrices/perspective-projection/)

When the perspective divide takes place - between the vertex and fragment shaders - the vertices are converted to normalized device coordinates (NDC), in "clip space." In this space, anything that fits in a 2x2x1 (x,y,z) box will be rendered. Any fragments that don't fit in a box with corners (-1, -1, 0) - (+1, +1, +1) will be clipped.

Practical Upshot Being

It doesn't matter what your zNear and zFar values are, as long as they offer sufficient resolution & precision, and zFar > zNear > 0.

Your collision detection & response system is responsible for keeping the camera from getting too close to the geometry. "Too close" is a function of your zNear and geometry bounds. Even if you have a zNear of 1E-9, geometry will get clipped when it gets too close to the clip space origin.

So: fix your collision detection and stop worrying about your zNear.