105 lines
3.3 KiB
Plaintext
105 lines
3.3 KiB
Plaintext
'\" e
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'\"! eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 24 September 1999
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.ds Re Release 1.2.1
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.ds Dp Jan 14 18:30
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.ds Dm 01 hint.gl -
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.ds Xs 8452 5 hint.gl
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.TH GLHINT 3G
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.SH NAME
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.B "glHint
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\- specify implementation-specific hints
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.SH C SPECIFICATION
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void \f3glHint\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3void \fPglHint( 'u
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GLenum \fImode\fP )
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.fi
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.SH PARAMETERS
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.TP \w'\f2target\fP\ \ 'u
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\f2target\fP
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Specifies a symbolic constant indicating the behavior to be controlled.
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\%\f3GL_FOG_HINT\fP,
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\%\f3GL_LINE_SMOOTH_HINT\fP,
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\%\f3GL_PERSPECTIVE_CORRECTION_HINT\fP,
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\%\f3GL_POINT_SMOOTH_HINT\fP, and
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\%\f3GL_POLYGON_SMOOTH_HINT\fP are accepted.
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.TP
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\f2mode\fP
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Specifies a symbolic constant indicating the desired behavior.
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\%\f3GL_FASTEST\fP,
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\%\f3GL_NICEST\fP, and
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\%\f3GL_DONT_CARE\fP are accepted.
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.SH DESCRIPTION
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Certain aspects of GL behavior,
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when there is room for interpretation,
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can be controlled with hints.
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A hint is specified with two arguments.
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\f2target\fP is a symbolic
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constant indicating the behavior to be controlled,
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and \f2mode\fP is another symbolic constant indicating the desired
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behavior. The initial value for each \f2target\fP is \%\f3GL_DONT_CARE\fP.
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\f2mode\fP can be one of the following:
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.TP 20
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\%\f3GL_FASTEST\fP
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The most efficient option should be chosen.
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.TP
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\%\f3GL_NICEST\fP
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The most correct,
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or highest quality,
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option should be chosen.
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.TP
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\%\f3GL_DONT_CARE\fP
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No preference.
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.P
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Though the implementation aspects that can be hinted are well defined,
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the interpretation of the hints depends on the implementation.
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The hint aspects that can be specified with \f2target\fP,
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along with suggested semantics,
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are as follows:
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.TP 20
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\%\f3GL_FOG_HINT\fP
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Indicates the accuracy of fog calculation.
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If per-pixel fog calculation is not efficiently supported
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by the GL implementation,
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hinting \%\f3GL_DONT_CARE\fP or \%\f3GL_FASTEST\fP can result in per-vertex
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calculation of fog effects.
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.TP
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\%\f3GL_LINE_SMOOTH_HINT\fP
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Indicates the sampling quality of antialiased lines.
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If a larger filter function is applied, hinting \%\f3GL_NICEST\fP can
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result in more pixel fragments being generated during rasterization,
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.TP
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\%\f3GL_PERSPECTIVE_CORRECTION_HINT\fP
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Indicates the quality of color and texture coordinate interpolation.
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If perspective-corrected parameter interpolation is not efficiently supported
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by the GL implementation,
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hinting \%\f3GL_DONT_CARE\fP or \%\f3GL_FASTEST\fP can result in simple linear
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interpolation of colors and/or texture coordinates.
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.TP
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\%\f3GL_POINT_SMOOTH_HINT\fP
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Indicates the sampling quality of antialiased points.
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If a larger filter function is applied, hinting \%\f3GL_NICEST\fP can
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result in more pixel fragments being generated during rasterization,
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.TP
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\%\f3GL_POLYGON_SMOOTH_HINT\fP
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Indicates the sampling quality of antialiased polygons.
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Hinting \%\f3GL_NICEST\fP can result in more pixel fragments being generated
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during rasterization,
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if a larger filter function is applied.
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.SH NOTES
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The interpretation of hints depends on the implementation.
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Some implementations ignore \%\f3glHint\fP settings.
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.SH ERRORS
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\%\f3GL_INVALID_ENUM\fP is generated if either \f2target\fP or \f2mode\fP is not
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an accepted value.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glHint\fP
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is executed between the execution of \%\f3glBegin\fP
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and the corresponding execution of \%\f3glEnd\fP.
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