'\" e '\"macro stdmacro .ds Vn Version 1.2 .ds Dt 24 September 1999 .ds Re Release 1.2.1 .ds Dp May 22 14:45 .ds Dm 2 May 22 14: .ds Xs 08452 5 .TH GLHINT 3G .SH NAME .B "glHint \- specify implementation-specific hints .SH C SPECIFICATION void \f3glHint\fP( GLenum \fItarget\fP, .nf .ta \w'\f3void \fPglHint( 'u GLenum \fImode\fP ) .fi .SH PARAMETERS .TP \w'\f2target\fP\ \ 'u \f2target\fP Specifies a symbolic constant indicating the behavior to be controlled. \%\f3GL_FOG_HINT\fP, \%\f3GL_LINE_SMOOTH_HINT\fP, \%\f3GL_PERSPECTIVE_CORRECTION_HINT\fP, \%\f3GL_POINT_SMOOTH_HINT\fP, and \%\f3GL_POLYGON_SMOOTH_HINT\fP are accepted. .TP \f2mode\fP Specifies a symbolic constant indicating the desired behavior. \%\f3GL_FASTEST\fP, \%\f3GL_NICEST\fP, and \%\f3GL_DONT_CARE\fP are accepted. .SH DESCRIPTION Certain aspects of GL behavior, when there is room for interpretation, can be controlled with hints. A hint is specified with two arguments. \f2target\fP is a symbolic constant indicating the behavior to be controlled, and \f2mode\fP is another symbolic constant indicating the desired behavior. The initial value for each \f2target\fP is \%\f3GL_DONT_CARE\fP. \f2mode\fP can be one of the following: .TP 20 \%\f3GL_FASTEST\fP The most efficient option should be chosen. .TP \%\f3GL_NICEST\fP The most correct, or highest quality, option should be chosen. .TP \%\f3GL_DONT_CARE\fP No preference. .P Though the implementation aspects that can be hinted are well defined, the interpretation of the hints depends on the implementation. The hint aspects that can be specified with \f2target\fP, along with suggested semantics, are as follows: .TP 20 \%\f3GL_FOG_HINT\fP Indicates the accuracy of fog calculation. If per-pixel fog calculation is not efficiently supported by the GL implementation, hinting \%\f3GL_DONT_CARE\fP or \%\f3GL_FASTEST\fP can result in per-vertex calculation of fog effects. .TP \%\f3GL_LINE_SMOOTH_HINT\fP Indicates the sampling quality of antialiased lines. If a larger filter function is applied, hinting \%\f3GL_NICEST\fP can result in more pixel fragments being generated during rasterization, .TP \%\f3GL_PERSPECTIVE_CORRECTION_HINT\fP Indicates the quality of color and texture coordinate interpolation. If perspective-corrected parameter interpolation is not efficiently supported by the GL implementation, hinting \%\f3GL_DONT_CARE\fP or \%\f3GL_FASTEST\fP can result in simple linear interpolation of colors and/or texture coordinates. .TP \%\f3GL_POINT_SMOOTH_HINT\fP Indicates the sampling quality of antialiased points. If a larger filter function is applied, hinting \%\f3GL_NICEST\fP can result in more pixel fragments being generated during rasterization, .TP \%\f3GL_POLYGON_SMOOTH_HINT\fP Indicates the sampling quality of antialiased polygons. Hinting \%\f3GL_NICEST\fP can result in more pixel fragments being generated during rasterization, if a larger filter function is applied. .SH NOTES The interpretation of hints depends on the implementation. Some implementations ignore \%\f3glHint\fP settings. .SH ERRORS \%\f3GL_INVALID_ENUM\fP is generated if either \f2target\fP or \f2mode\fP is not an accepted value. .P \%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glHint\fP is executed between the execution of \%\f3glBegin\fP and the corresponding execution of \%\f3glEnd\fP.