sync code with last improvements from OpenBSD

doc/gl-docs/GL/gl/clearaccum.3gl

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+'\" te
+'\"! tbl|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 clearaccu
+.ds Xs 2071 3 clearaccum.gl
+.TH GLCLEARACCUM 3G
+.SH NAME
+.B "glClearAccum
+\- specify clear values for the accumulation buffer
+
+.SH C SPECIFICATION
+void \f3glClearAccum\fP(
+GLfloat \fIred\fP,
+.nf
+.ta \w'\f3void \fPglClearAccum( 'u
+	GLfloat \fIgreen\fP,
+	GLfloat \fIblue\fP,
+	GLfloat \fIalpha\fP )
+.fi
+
+.SH PARAMETERS
+.TP \w'\f2red\fP\ \f2green\fP\ \f2blue\fP\ \f2alpha\fP\ \ 'u 
+\f2red\fP, \f2green\fP, \f2blue\fP, \f2alpha\fP
+Specify the red, green, blue, and alpha values used when the
+accumulation buffer is cleared.
+The initial values are all 0.
+.SH DESCRIPTION
+\%\f3glClearAccum\fP specifies the red, green, blue, and alpha values used by \%\f3glClear\fP 
+to clear the accumulation buffer.
+.P
+Values specified by \%\f3glClearAccum\fP are clamped to the 
+range [-1,\ 1].
+.SH ERRORS
+\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glClearAccum\fP
+is executed between the execution of \%\f3glBegin\fP
+and the corresponding execution of \%\f3glEnd\fP.
+.SH ASSOCIATED GETS
+\%\f3glGet\fP with argument \%\f3GL_ACCUM_CLEAR_VALUE\fP
+.SH SEE ALSO
+\%\f3glAccum(3G)\fP,
+\%\f3glClear(3G)\fP