lsetdepth(3G)

NAME
     lsetdepth - sets the depth range

C SPECIFICATION
     void lsetdepth(near, far)
     long near, far;

PARAMETERS
     near   expects the screen coordinate of the near clipping plane.

     far    expects the screen coordinate of the far clipping plane.

DESCRIPTION
     viewport specifies the mapping of the left, right, bottom, and top
     clipping planes into screen coordinates.  lsetdepth completes this
     mapping for homogeneous world coordinates; it specifies the mapping of
     the near and far clipping planes into values stored in the z-buffer.

     lsetdepth is used in z-buffering, depth-cueing, and certain feedback
     applications.

     The valid range of the parameters depends on the state of the
     GLC_ZRANGEMAP compatibility mode (see glcompat).  If it is 0, the valid
     range depends on the graphics hardware.  When multisample is enabled, and
     multisample buffers exist in the current framebuffer configuration in the
     current drawmode, the minimum is the value returned by
     getgconfig(GC_MS_ZMIN) and the maximum is the value returned by
     getgconfig(GC_MS_ZMAX).  Otherwise, the minimum is the value returned by
     getgconfig(GC_ZMIN) and the maximum is the value returned by
     getgconfig(GC_ZMAX).  If the state of the GLC_ZRANGEMAP compatibility
     mode is 1, the minimum is 0x0 and the maximum is 0x7FFFFF.  The depth
     range defaults to the full range supported by the graphics hardware.

     Acceptable mappings include all those where both near and far are within
     the supported range, including mappings where near > far.  In particular,
     it is sometimes desirable to call lsetdepth(0x7FFFFF, 0x0) on IRIS-4D GT
     and GTX models.

SEE ALSO
     depthcue, feedback, getgdesc, glcompat, zbuffer

NOTES
     Error accumulation in the iteration of z can cause wrapping when the full
     depth range supported by the graphics hardware is used.  (An iteration
     wraps when it accidentally converts an large positive value into a
     negative value, or vice versa.)  While the effects of wrapping are
     typically not observed, if they are, they can be eliminated by reducing
     the depth range by a small percentage.

     When using this routine, you should always explicitly set the
     GLC_ZRANGEMAP mode of glcompat because its default is different on
     different models.