lsetdepth(3G)							 lsetdepth(3G)

NAME    [Toc]    [Back]

     lsetdepth - sets the depth	range

C SPECIFICATION    [Toc]    [Back]

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

PARAMETERS    [Toc]    [Back]

     near   expects the	screen coordinate of the near clipping plane.

     far    expects the	screen coordinate of the far clipping plane.

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

     depthcue, feedback, getgdesc, glcompat, zbuffer

NOTES    [Toc]    [Back]

     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.


									PPPPaaaaggggeeee 1111