89 lines
2.4 KiB
Plaintext
89 lines
2.4 KiB
Plaintext
'\" te
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'\"! tbl|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 depthfunc
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.ds Xs 34310 5 depthfunc.gl
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.TH GLDEPTHFUNC 3G
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.SH NAME
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.B "glDepthFunc
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\- specify the value used for depth buffer comparisons
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.SH C SPECIFICATION
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void \f3glDepthFunc\fP(
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GLenum \fIfunc\fP )
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.nf
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.fi
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.SH PARAMETERS
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.TP \w'\f2func\fP\ \ 'u
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\f2func\fP
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Specifies the depth comparison function.
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Symbolic constants
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\%\f3GL_NEVER\fP,
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\%\f3GL_LESS\fP,
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\%\f3GL_EQUAL\fP,
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\%\f3GL_LEQUAL\fP,
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\%\f3GL_GREATER\fP,
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\%\f3GL_NOTEQUAL\fP,
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\%\f3GL_GEQUAL\fP, and
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\%\f3GL_ALWAYS\fP are accepted.
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The initial value is \%\f3GL_LESS\fP.
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.SH DESCRIPTION
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\%\f3glDepthFunc\fP specifies the function used to compare each incoming pixel depth value
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with the depth value present in the depth buffer.
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The comparison is performed only if depth testing is enabled.
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(See \%\f3glEnable\fP and \%\f3glDisable\fP of \%\f3GL_DEPTH_TEST\fP.)
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.P
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\f2func\fP specifies the conditions under which the pixel will be drawn.
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The comparison functions are as follows:
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.TP 16
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\%\f3GL_NEVER\fP
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Never passes.
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.TP
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\%\f3GL_LESS\fP
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Passes if the incoming depth value is less than the stored depth value.
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.TP
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\%\f3GL_EQUAL\fP
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Passes if the incoming depth value is equal to the stored depth value.
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.TP
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\%\f3GL_LEQUAL\fP
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Passes if the incoming depth value is less than or equal to
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the stored depth value.
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.TP
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\%\f3GL_GREATER\fP
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Passes if the incoming depth value is greater than the stored depth value.
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.TP
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\%\f3GL_NOTEQUAL\fP
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Passes if the incoming depth value is not equal to the stored depth value.
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.TP
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\%\f3GL_GEQUAL\fP
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Passes if the incoming depth value is greater than or equal to
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the stored depth value.
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.TP
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\%\f3GL_ALWAYS\fP
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Always passes.
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.P
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The initial value of \f2func\fP is \%\f3GL_LESS\fP.
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Initially, depth testing is disabled.
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.NOTES
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Even if the depth buffer exists and the depth mask is non-zero, the
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depth buffer is not updated if the depth test is disabled.
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.SH ERRORS
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\%\f3GL_INVALID_ENUM\fP is generated if \f2func\fP is not an accepted value.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glDepthFunc\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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.SH ASSOCIATED GETS
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\%\f3glGet\fP with argument \%\f3GL_DEPTH_FUNC\fP
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.br
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\%\f3glIsEnabled\fP with argument \%\f3GL_DEPTH_TEST\fP
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.SH SEE ALSO
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\%\f3glDepthRange(3G)\fP,
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\%\f3glEnable(3G)\fP,
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\%\f3glPolygonOffset(3G)\fP
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