133 lines
4.3 KiB
Plaintext
133 lines
4.3 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 bitmap.gl
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.ds Xs 23189 6 bitmap.gl
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.TH GLBITMAP 3G
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.SH NAME
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.B "glBitmap
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\- draw a bitmap
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.SH C SPECIFICATION
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void \f3glBitmap\fP(
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GLsizei \fIwidth\fP,
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.nf
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.ta \w'\f3void \fPglBitmap( 'u
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GLsizei \fIheight\fP,
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GLfloat \fIxorig\fP,
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GLfloat \fIyorig\fP,
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GLfloat \fIxmove\fP,
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GLfloat \fIymove\fP,
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const GLubyte \fI*bitmap\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\f2width\fP\ \f2height\fP\ \ 'u
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\f2width\fP, \f2height\fP
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Specify the pixel width and height of the bitmap image.
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.TP
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\f2xorig\fP, \f2yorig\fP
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Specify the location of the origin in the bitmap image.
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The origin is measured from the lower left corner of the bitmap,
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with right and up being the positive axes.
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.TP
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\f2xmove\fP, \f2ymove\fP
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Specify the \f2x\fP and \f2y\fP offsets to be added to the current raster position
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after the bitmap is drawn.
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.TP
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\f2bitmap\fP
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Specifies the address of the bitmap image.
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.SH DESCRIPTION
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A bitmap is a binary image.
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When drawn,
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the bitmap is positioned relative to the current raster position,
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and frame buffer pixels corresponding to 1's in the bitmap are
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written using the current raster color or index.
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Frame buffer pixels corresponding to 0's in the bitmap are not modified.
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.P
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\%\f3glBitmap\fP takes seven arguments.
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The first pair specifies the width and height of the bitmap image.
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The second pair specifies the location of the bitmap origin relative
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to the lower left corner of the bitmap image.
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The third pair of arguments specifies \f2x\fP and \f2y\fP offsets to be added
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to the current raster position after the bitmap has been drawn.
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The final argument is a pointer to the bitmap image itself.
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.P
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The bitmap image is interpreted like image data for the \%\f3glDrawPixels\fP
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command,
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with \f2width\fP and \f2height\fP corresponding to the width and height arguments
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of that command,
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and with \f2type\fP set to \%\f3GL_BITMAP\fP
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and \f2format\fP set to \%\f3GL_COLOR_INDEX\fP.
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.BP
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Modes specified using \%\f3glPixelStore\fP affect the
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interpretation of bitmap image data;
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modes specified using \%\f3glPixelTransfer\fP do not.
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.P
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If the current raster position is invalid, \%\f3glBitmap\fP is ignored.
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Otherwise,
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the lower left corner of the bitmap image is positioned at the window coordinates
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.ce
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.sp
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$ x sub w ~=~ \(lf ~ x sub r ~-~ x sub o ~ \(rf $
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.br
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.sp
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.ce
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$ y sub w ~=~ \(lf ~ y sub r ~-~ y sub o ~ \(rf $
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.sp
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where $ ( x sub r , y sub r ) $ is the raster position
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and $ ( x sub o , y sub o ) $ is the bitmap origin.
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Fragments are then generated for each pixel corresponding to a 1 (one)
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in the bitmap image.
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These fragments are generated using the current raster \f2z\fP coordinate,
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color or color index, and current raster texture coordinates.
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They are then treated just as if they had been generated
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by a point, line, or polygon,
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including texture mapping,
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.br
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fogging,
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and all per-fragment operations such as alpha and depth testing.
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.P
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After the bitmap has been drawn,
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the \f2x\fP and \f2y\fP coordinates of the current raster position are offset by
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\f2xmove\fP and \f2ymove\fP.
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No change is made to the \f2z\fP coordinate of the current raster position,
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or to the current raster color, texture coordinates, or index.
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.SH NOTES
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To set a valid raster position outside the viewport, first set a valid
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raster position inside the viewport, then call \%\f3glBitmap\fP with NULL
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as the \f2bitmap\fP parameter and with \f2xmove\fP and \f2ymove\fP set to
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the offsets of the new raster position. This technique is useful when
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panning an image around the viewport.
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.SH ERRORS
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\%\f3GL_INVALID_VALUE\fP is generated if \f2width\fP or \f2height\fP is negative.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glBitmap\fP
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is executed between the execution of \%\f3glBegin\fP and the corresponding execution of
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\%\f3glEnd\fP.
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.SH ASSOCIATED GETS
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\%\f3glGet\fP with argument \%\f3GL_CURRENT_RASTER_POSITION\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_CURRENT_RASTER_COLOR\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_CURRENT_RASTER_DISTANCE\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_CURRENT_RASTER_INDEX\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_CURRENT_RASTER_TEXTURE_COORDS\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_CURRENT_RASTER_POSITION_VALID\fP
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.SH SEE ALSO
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\%\f3glDrawPixels(3G)\fP,
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\%\f3glPixelStore(3G)\fP,
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\%\f3glPixelTransfer(3G)\fP,
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\%\f3glRasterPos(3G)\fP
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