'\" t '\"! tbl | 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 minmax.gl .ds Xs 45595 6 minmax.gl .TH GLMINMAX 3G .SH NAME .B "glMinmax \- define minmax table .SH C SPECIFICATION void \f3glMinmax\fP( GLenum \fItarget\fP, .nf .ta \w'\f3void \fPglMinmax( 'u GLenum \fIinternalformat\fP, GLboolean \fIsink\fP ) .fi .SH PARAMETERS .TP \w'\fIinternalformat\fP\ \ 'u \f2target\fP The minmax table whose parameters are to be set. Must be \%\f3GL_MINMAX\fP. .TP \f2internalformat\fP The of entries in the minmax table. Must be one of \%\f3GL_ALPHA\fP, \%\f3GL_ALPHA4\fP, \%\f3GL_ALPHA8\fP, \%\f3GL_ALPHA12\fP, \%\f3GL_ALPHA16\fP, \%\f3GL_LUMINANCE\fP, \%\f3GL_LUMINANCE4\fP, \%\f3GL_LUMINANCE8\fP, \%\f3GL_LUMINANCE12\fP, \%\f3GL_LUMINANCE16\fP, \%\f3GL_LUMINANCE_ALPHA\fP, \%\f3GL_LUMINANCE4_ALPHA4\fP, \%\f3GL_LUMINANCE6_ALPHA2\fP, \%\f3GL_LUMINANCE8_ALPHA8\fP, \%\f3GL_LUMINANCE12_ALPHA4\fP, \%\f3GL_LUMINANCE12_ALPHA12\fP, \%\f3GL_LUMINANCE16_ALPHA16\fP, \%\f3GL_R3_G3_B2\fP, \%\f3GL_RGB\fP, \%\f3GL_RGB4\fP, \%\f3GL_RGB5\fP, \%\f3GL_RGB8\fP, \%\f3GL_RGB10\fP, \%\f3GL_RGB12\fP, \%\f3GL_RGB16\fP, \%\f3GL_RGBA\fP, \%\f3GL_RGBA2\fP, \%\f3GL_RGBA4\fP, \%\f3GL_RGB5_A1\fP, \%\f3GL_RGBA8\fP, \%\f3GL_RGB10_A2\fP, \%\f3GL_RGBA12\fP, or \%\f3GL_RGBA16\fP. .TP \f2sink\fP If \%\f3GL_TRUE\fP, pixels will be consumed by the minmax process and no drawing or texture loading will take place. If \%\f3GL_FALSE\fP, pixels will proceed to the final conversion process after minmax. .SH DESCRIPTION When \%\f3GL_MINMAX\fP is enabled, the RGBA components of incoming pixels are compared to the minimum and maximum values for each component, which are stored in the 2-element minmax table. (The first element stores the minima, and the second element stores the maxima.) If a pixel component is greater than the corresponding component in the maximum element, then the maximum element is updated with the pixel component value. If a pixel component is less than the corresponding component in the minimum element, then the minimum element is updated with the pixel component value. (In both cases, if the internal of the minmax table includes luminance, then the R color component of incoming pixels is used for comparison.) The contents of the minmax table may be retrieved at a later time by calling \%\f3glGetMinmax\fP. The minmax operation is enabled or disabled by calling \%\f3glEnable\fP or \%\f3glDisable\fP, respectively, with an argument of \%\f3GL_MINMAX\fP. .P \%\f3glMinmax\fP redefines the current minmax table to have entries of the specified by \f2internalformat\fP. The maximum element is initialized with the smallest possible component values, and the minimum element is initialized with the largest possible component values. The values in the previous minmax table, if any, are lost. If \f2sink\fP is \%\f3GL_TRUE\fP, then pixels are discarded after minmax; no further processing of the pixels takes place, and no drawing, texture loading, or pixel readback will result. .P .SH NOTES \%\f3glMinmax\fP is present only if \%\f3GL_ARB_imaging\fP is returned when \%\f3glGetString\fP is called with an argument of \%\f3GL_EXTENSIONS\fP. .SH ERRORS \%\f3GL_INVALID_ENUM\fP is generated if \f2target\fP is not one of the allowable values. .P \%\f3GL_INVALID_ENUM\fP is generated if \f2internalformat\fP is not one of the allowable values. .P \%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glMinmax\fP is executed between the execution of \%\f3glBegin\fP and the corresponding execution of \%\f3glEnd\fP. .SH ASSOCIATED GETS \%\f3glGetMinmaxParameter\fP .SH SEE ALSO \%\f3glGetMinmax(3G)\fP, \%\f3glResetMinmax(3G)\fP