IABSD.fr/xenocara/doc/gl-docs/GL/gl/polygonoffset.3gl

Branch : - branch - master - tag -

• Show log

  Commit

• Author : matthieu
  Date : 2006-11-29 17:00:35
  Hash : 36da9a5e
  Message : OpenGL manual pages from monolithic tree.

• doc/gl-docs/GL/gl/polygonoffset.3gl

• '\" e
  '\"! eqn | mmdoc
  '\"macro stdmacro
  .ds Vn Version 1.2
  .ds Dt 24 September 1999
  .ds Re Release 1.2.1
  .ds Dp Jan 14 18:30
  .ds Dm 01 polygonof
  .ds Xs 10762 4 polygonoffset.gl
  .TH GLPOLYGONOFFSET 3G
  .SH NAME
  .B "glPolygonOffset
  \- set the scale and units used to calculate depth values
  
  .SH C SPECIFICATION
  void \f3glPolygonOffset\fP(
  GLfloat \fIfactor\fP,
  .nf
  .ta \w'\f3void \fPglPolygonOffset( 'u
  	GLfloat \fIunits\fP )
  .fi
  
  .EQ
  delim $$
  .EN
  .SH PARAMETERS
  .TP \w'\f2factor\fP\ \ 'u 
  \f2factor\fP 
  Specifies a scale factor that is used to create a variable
  depth offset for each polygon. The initial value is 0.
  .TP
  \f2units\fP 
  Is multiplied by an implementation-specific value to
  create a constant depth offset. The initial value is 0.
  .SH DESCRIPTION
  When \%\f3GL_POLYGON_OFFSET_FILL\fP, \%\f3GL_POLYGON_OFFSET_LINE\fP, or
  \%\f3GL_POLYGON_OFFSET_POINT\fP is enabled, each
  fragment's \f2depth\fP value will be offset after it is interpolated
  from the \f2depth\fP values of the appropriate vertices.
  The value of the offset is $"factor" ~*~ DZ ~~+~~ r ~*~ "units"$,
  where $DZ~$ is a measurement of the change in depth relative to the screen 
  area of the polygon, and $r$ is the smallest value that is guaranteed to
  produce a resolvable offset for a given implementation.
  The offset is added before the depth test is performed and before
  the value is written into the depth buffer.
  .P
  \%\f3glPolygonOffset\fP is useful for rendering hidden-line images, for applying decals 
  to surfaces, and for rendering solids with highlighted edges.
  .SH NOTES
  \%\f3glPolygonOffset\fP is available only if the GL version is 1.1 or greater.
  .P
  \%\f3glPolygonOffset\fP has no effect on depth coordinates placed in the
  feedback buffer.
  .P
  \%\f3glPolygonOffset\fP has no effect on selection.
  .SH ERRORS
  \%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glPolygonOffset\fP is executed
  between the execution of \%\f3glBegin\fP and the corresponding
  execution of \%\f3glEnd\fP.
  .bp
  .SH ASSOCIATED GETS
  \%\f3glIsEnabled\fP with argument 
  \%\f3GL_POLYGON_OFFSET_FILL\fP, 
  \%\f3GL_POLYGON_OFFSET_LINE\fP, 
  or \%\f3GL_POLYGON_OFFSET_POINT\fP.
  .P
  \%\f3glGet\fP with argument \%\f3GL_POLYGON_OFFSET_FACTOR\fP or 
  \%\f3GL_POLYGON_OFFSET_UNITS\fP.
  .SH SEE ALSO
  \%\f3glDepthFunc(3G)\fP,
  \%\f3glEnable(3G)\fP,
  \%\f3glGet(3G)\fP,
  \%\f3glIsEnabled(3G)\fP