path: root/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/pixeltransfer.gl

_C_ License Applicability. Except to the extent portions of this file are
_C_ made subject to an alternative license as permitted in the SGI Free
_C_ Software License B, Version 1.1 (the "License"), the contents of this
_C_ file are subject only to the provisions of the License. You may not use
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_C_ 
_C_ Original Code. The Original Code is: OpenGL Sample Implementation,
_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
_C_ Copyright in any portions created by third parties is as indicated
_C_ elsewhere herein. All Rights Reserved.
_C_ 
_C_ Additional Notice Provisions: The application programming interfaces
_C_ established by SGI in conjunction with the Original Code are The
_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
_C_ Window System(R) (Version 1.3), released October 19, 1998. This software
_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation
_C_ published by SGI, but has not been independently verified as being
_C_ compliant with the OpenGL(R) version 1.2.1 Specification.
_C_
_C_ The first character in this file must be an '_'!
_C_ Anything on a line after _C_ is ignored
_define(_filters,tbl|eqn)_C_
_C_      eqn is automatically replaced with neqn for nroff
_header(PixelTransfer, set pixel transfer modes)
_names(PixelTransfer,[fi])
.EQ
delim $$
.EN
.SH PARAMETERS
_phead(_param1)
Specifies the symbolic name of the pixel transfer parameter to be set.
Must be one of the following:
_const(MAP_COLOR),
_const(MAP_STENCIL),
_const(INDEX_SHIFT),
_const(INDEX_OFFSET),
_const(RED_SCALE),
_const(RED_BIAS),
_const(GREEN_SCALE),
_const(GREEN_BIAS),
_const(BLUE_SCALE),
_const(BLUE_BIAS),
_const(ALPHA_SCALE),
_const(ALPHA_BIAS),
_const(DEPTH_SCALE), or
_const(DEPTH_BIAS).
.IP
Additionally, if the _arbstring(imaging) extension is supported, the
following symbolic names are accepted:
_const(POST_COLOR_MATRIX_RED_SCALE),
_const(POST_COLOR_MATRIX_GREEN_SCALE),
_const(POST_COLOR_MATRIX_BLUE_SCALE),
_const(POST_COLOR_MATRIX_ALPHA_SCALE),
_const(POST_COLOR_MATRIX_RED_BIAS),
_const(POST_COLOR_MATRIX_GREEN_BIAS),
_const(POST_COLOR_MATRIX_BLUE_BIAS),
_const(POST_COLOR_MATRIX_ALPHA_BIAS),
_const(POST_CONVOLUTION_RED_SCALE),
_const(POST_CONVOLUTION_GREEN_SCALE),
_const(POST_CONVOLUTION_BLUE_SCALE),
_const(POST_CONVOLUTION_ALPHA_SCALE),
_const(POST_CONVOLUTION_RED_BIAS),
_const(POST_CONVOLUTION_GREEN_BIAS),
_const(POST_CONVOLUTION_BLUE_BIAS), and
_const(POST_CONVOLUTION_ALPHA_BIAS).
_phead(_param2)
Specifies the value that _param1 is set to.
.SH DESCRIPTION
_cmnd sets pixel transfer modes that affect the operation of subsequent
_cmnd(CopyPixels),
_cmnd(CopyTexImage1D),
_cmnd(CopyTexImage2D),
_cmnd(CopyTexSubImage1D),
_cmnd(CopyTexSubImage2D),
_cmnd(CopyTexSubImage3D),
_cmnd(DrawPixels),
_cmnd(ReadPixels),
_cmnd(TexImage1D),
_cmnd(TexImage2D),
_cmnd(TexImage3D),
_cmnd(TexSubImage1D),
_cmnd(TexSubImage2D), and
_cmnd(TexSubImage3D) commands.
Additionally, if the _arbstring(imaging) subset is supported, the
routines
_cmnd(ColorTable),
_cmnd(ColorSubTable),
_cmnd(ConvolutionFilter1D),
_cmnd(ConvolutionFilter2D),
_cmnd(Histogram),
_cmnd(Minmax), and
_cmnd(SeparableFilter2D) are also affected.
The algorithms that are specified by pixel transfer modes operate on
pixels after they are read from the frame buffer
(_cmnd(CopyPixels)
_cmnd(CopyTexImage1D),
_cmnd(CopyTexImage2D),
_cmnd(CopyTexSubImage1D),
_cmnd(CopyTexSubImage2D),
_cmnd(CopyTexSubImage3D), and
_cmnd(ReadPixels)),
or unpacked from client memory
(_cmnd(DrawPixels), _cmnd(TexImage1D), _cmnd(TexImage2D), _cmnd(TexImage3D),
_cmnd(TexSubImage1D), _cmnd(TexSubImage2D), and _cmnd(TexSubImage3D)). 
Pixel transfer operations happen in the same order,
and in the same manner,
regardless of the command that resulted in the pixel operation.
Pixel storage modes
(see _cmnd(PixelStore))
control the unpacking of pixels being read from client memory,
and the packing of pixels being written back into client memory.
.P
Pixel transfer operations handle four fundamental pixel types:
\f2color\fP,
\f2color index\fP,
\f2depth\fP, and
\f2stencil\fP.
\f2Color\fP pixels consist of four floating-point values
with unspecified mantissa and exponent sizes,
scaled such that 0 represents zero intensity
and 1 represents full intensity.
\f2Color indices\fP comprise a single fixed-point value,
with unspecified precision to the right of the binary point.
\f2Depth\fP pixels comprise a single floating-point value,
with unspecified mantissa and exponent sizes,
scaled such that 0.0 represents the minimum depth buffer value,
and 1.0 represents the maximum depth buffer value.
Finally,
\f2stencil\fP pixels comprise a single fixed-point value,
with unspecified precision to the right of the binary point.
.BP
.P
The pixel transfer operations performed on the four basic pixel types are 
as follows:
.TP 12
Color
Each of the four color components is multiplied by a scale factor,
then added to a bias factor.
That is,
the red component is multiplied by _const(RED_SCALE),
then added to _const(RED_BIAS);
the green component is multiplied by _const(GREEN_SCALE),
then added to _const(GREEN_BIAS);
the blue component is multiplied by _const(BLUE_SCALE),
then added to _const(BLUE_BIAS); and
the alpha component is multiplied by _const(ALPHA_SCALE),
then added to _const(ALPHA_BIAS).
After all four color components are scaled and biased,
each is clamped to the range [0,1].
All color, scale, and bias values are specified with _cmnd.
.IP
If _const(MAP_COLOR) is true,
each color component is scaled by the size of the corresponding
color-to-color map,
then replaced by the contents of that map indexed by the scaled component.
That is,
the red component is scaled by _const(PIXEL_MAP_R_TO_R_SIZE),
then replaced by the contents of _const(PIXEL_MAP_R_TO_R) indexed by itself.
The green component is scaled by _const(PIXEL_MAP_G_TO_G_SIZE),
then replaced by the contents of _const(PIXEL_MAP_G_TO_G) indexed by itself.
The blue component is scaled by _const(PIXEL_MAP_B_TO_B_SIZE),
then replaced by the contents of _const(PIXEL_MAP_B_TO_B) indexed by itself.
And
the alpha component is scaled by _const(PIXEL_MAP_A_TO_A_SIZE),
then replaced by the contents of _const(PIXEL_MAP_A_TO_A) indexed by itself.
All components taken from the maps are then clamped to the range [0,1].
_const(MAP_COLOR) is specified with _cmnd.
The contents of the various maps are specified with _cmnd(PixelMap).
.IP
If the _arbstring(imaging) extension is supported, each of the four
color components may be scaled and biased after tranformation by the
color matrix.  
That is,
the red component is multiplied by _const(POST_COLOR_MATRIX_RED_SCALE),
then added to _const(POST_COLOR_MATRIX_RED_BIAS);
the green component is multiplied by _const(POST_COLOR_MATRIX_GREEN_SCALE),
then added to _const(POST_COLOR_MATRIX_GREEN_BIAS);
the blue component is multiplied by _const(POST_COLOR_MATRIX_BLUE_SCALE),
then added to _const(POST_COLOR_MATRIX_BLUE_BIAS); and
the alpha component is multiplied by _const(POST_COLOR_MATRIX_ALPHA_SCALE),
then added to _const(POST_COLOR_MATRIX_ALPHA_BIAS).
After all four color components are scaled and biased,
each is clamped to the range [0,1].
.IP
Similiarly, if the _arbstring(imaging) extension is supported, each of
the four color components may be scaled and biased after processing by
the enabled convolution filter.
That is,
the red component is multiplied by _const(POST_CONVOLUTION_RED_SCALE),
then added to _const(POST_CONVOLUTION_RED_BIAS);
the green component is multiplied by _const(POST_CONVOLUTION_GREEN_SCALE),
then added to _const(POST_CONVOLUTION_GREEN_BIAS);
the blue component is multiplied by _const(POST_CONVOLUTION_BLUE_SCALE),
then added to _const(POST_CONVOLUTION_BLUE_BIAS); and
the alpha component is multiplied by _const(POST_CONVOLUTION_ALPHA_SCALE),
then added to _const(POST_CONVOLUTION_ALPHA_BIAS).
After all four color components are scaled and biased,
each is clamped to the range [0,1].
.TP
Color index
Each color index is shifted left by _const(INDEX_SHIFT) bits; any bits
beyond the number of fraction bits carried
by the fixed-point index are filled with zeros.
If _const(INDEX_SHIFT) is negative,
the shift is to the right,
again zero filled.
Then _const(INDEX_OFFSET) is added to the index.
_const(INDEX_SHIFT) and _const(INDEX_OFFSET) are specified with 
.br
_cmnd.
.IP
From this point, operation diverges depending on the required format of
the resulting pixels.
If the resulting pixels are to be written to a color index buffer,
or if they are being read back to client memory in _const(COLOR_INDEX) format,
the pixels continue to be treated as indices.
If _const(MAP_COLOR) is true,
each index is masked by $2 sup n ~-~ 1$,
where $n$ is _const(PIXEL_MAP_I_TO_I_SIZE),
then replaced by the contents of _const(PIXEL_MAP_I_TO_I) indexed by the
masked value.
_const(MAP_COLOR) is specified with _cmnd.
The contents of the index map is specified with _cmnd(PixelMap).
.IP
If the resulting pixels are to be written to an RGBA color buffer,
or if they are read back to client memory in a format other than
_const(COLOR_INDEX),
the pixels are converted from indices to colors by referencing the
four maps
_const(PIXEL_MAP_I_TO_R),
_const(PIXEL_MAP_I_TO_G),
_const(PIXEL_MAP_I_TO_B), and
_const(PIXEL_MAP_I_TO_A).
Before being dereferenced,
the index is masked by $2 sup n ~-~ 1$,
where $n$ is
_const(PIXEL_MAP_I_TO_R_SIZE) for the red map,
_const(PIXEL_MAP_I_TO_G_SIZE) for the green map,
_const(PIXEL_MAP_I_TO_B_SIZE) for the blue map, and
_const(PIXEL_MAP_I_TO_A_SIZE) for the alpha map.
All components taken from the maps are then clamped to the range [0,1].
The contents of the four maps is specified with _cmnd(PixelMap).
.TP
Depth
Each depth value is multiplied by _const(DEPTH_SCALE),
added to _const(DEPTH_BIAS),
then clamped to the range [0,1].
.TP
Stencil
Each index is shifted _const(INDEX_SHIFT) bits just as a color index is,
then added to _const(INDEX_OFFSET).
If _const(MAP_STENCIL) is true,
each index is masked by $2 sup n ~-~ 1$,
where $n$ is _const(PIXEL_MAP_S_TO_S_SIZE),
then replaced by the contents of _const(PIXEL_MAP_S_TO_S) indexed by the
masked value.
.P
The following table gives the type,
initial value,
and range of valid values for each of the pixel transfer parameters
that are set with _cmnd.
.sp

.TS
center tab(:);
lb cb cb cb
l c c c.
_
_param1:Type:Initial Value:Valid Range
_
_const(MAP_COLOR):boolean:false:true/false
_const(MAP_STENCIL):boolean:false:true/false
_const(INDEX_SHIFT):integer:0:(-\(if,\(if)
_const(INDEX_OFFSET):integer:0:(-\(if,\(if)
_const(RED_SCALE):float:1:(-\(if,\(if)
_const(GREEN_SCALE):float:1:(-\(if,\(if)
_const(BLUE_SCALE):float:1:(-\(if,\(if)
_const(ALPHA_SCALE):float:1:(-\(if,\(if)
_const(DEPTH_SCALE):float:1:(-\(if,\(if)
_const(RED_BIAS):float:0:(-\(if,\(if)
_const(GREEN_BIAS):float:0:(-\(if,\(if)
_const(BLUE_BIAS):float:0:(-\(if,\(if)
_const(ALPHA_BIAS):float:0:(-\(if,\(if)
_const(DEPTH_BIAS):float:0:(-\(if,\(if)
_const(POST_COLOR_MATRIX_RED_SCALE):float:1:(-\(if,\(if)
_const(POST_COLOR_MATRIX_GREEN_SCALE):float:1:(-\(if,\(if)
_const(POST_COLOR_MATRIX_BLUE_SCALE):float:1:(-\(if,\(if)
_const(POST_COLOR_MATRIX_ALPHA_SCALE):float:1:(-\(if,\(if)
_const(POST_COLOR_MATRIX_RED_BIAS):float:0:(-\(if,\(if)
_const(POST_COLOR_MATRIX_GREEN_BIAS):float:0:(-\(if,\(if)
_const(POST_COLOR_MATRIX_BLUE_BIAS):float:0:(-\(if,\(if)
_const(POST_COLOR_MATRIX_ALPHA_BIAS):float:0:(-\(if,\(if)
_const(POST_CONVOLUTION_RED_SCALE):float:1:(-\(if,\(if)
_const(POST_CONVOLUTION_GREEN_SCALE):float:1:(-\(if,\(if)
_const(POST_CONVOLUTION_BLUE_SCALE):float:1:(-\(if,\(if)
_const(POST_CONVOLUTION_ALPHA_SCALE):float:1:(-\(if,\(if)
_const(POST_CONVOLUTION_RED_BIAS):float:0:(-\(if,\(if)
_const(POST_CONVOLUTION_GREEN_BIAS):float:0:(-\(if,\(if)
_const(POST_CONVOLUTION_BLUE_BIAS):float:0:(-\(if,\(if)
_const(POST_CONVOLUTION_ALPHA_BIAS):float:0:(-\(if,\(if)
_
.TE

.sp
_cmnd(PixelTransferf) can be used to set any pixel transfer parameter.
If the parameter type is boolean,
0 implies false and any other value implies true.
If _param1 is an integer parameter,
_param2 is rounded to the nearest integer.
.P
Likewise,
_cmnd(PixelTransferi) can be used to set any of the
pixel transfer parameters.
Boolean parameters are set to false if _param2 is 0 and to true otherwise.
_param2 is converted to floating point before being assigned to real-valued parameters.
.SH NOTES
If a
_cmnd(ColorTable),
_cmnd(ColorSubTable),
_cmnd(ConvolutionFilter1D),
_cmnd(ConvolutionFilter2D),
_cmnd(CopyPixels),
_cmnd(CopyTexImage1D),
_cmnd(CopyTexImage2D),
_cmnd(CopyTexSubImage1D),
_cmnd(CopyTexSubImage2D),
_cmnd(CopyTexSubImage3D),
_cmnd(DrawPixels),
_cmnd(ReadPixels),
_cmnd(SeparableFilter2D),
_cmnd(TexImage1D),
_cmnd(TexImage2D),
_cmnd(TexImage3D),
_cmnd(TexSubImage1D),
_cmnd(TexSubImage2D), or
_cmnd(TexSubImage3D).
command is placed in a display list
(see _cmnd(NewList) and _cmnd(CallList)),
the pixel transfer mode settings in effect when the display list is
.I executed
are the ones that are used.
They may be different from the settings when the command was compiled
into the display list.
.SH ERRORS
_const(INVALID_ENUM) is generated if _param1 is not an accepted value.
.P
_const(INVALID_OPERATION) is generated if _cmnd
is executed between the execution of _cmnd(Begin)
and the corresponding execution of _cmnd(End).
.SH ASSOCIATED GETS
_cmnd(Get) with argument _const(MAP_COLOR)
.br
_cmnd(Get) with argument _const(MAP_STENCIL)
.br
_cmnd(Get) with argument _const(INDEX_SHIFT)
.br
_cmnd(Get) with argument _const(INDEX_OFFSET)
.br
_cmnd(Get) with argument _const(RED_SCALE)
.br
_cmnd(Get) with argument _const(RED_BIAS)
.br
_cmnd(Get) with argument _const(GREEN_SCALE)
.br
_cmnd(Get) with argument _const(GREEN_BIAS)
.br
_cmnd(Get) with argument _const(BLUE_SCALE)
.br
_cmnd(Get) with argument _const(BLUE_BIAS)
.br
_cmnd(Get) with argument _const(ALPHA_SCALE)
.br
_cmnd(Get) with argument _const(ALPHA_BIAS)
.br
_cmnd(Get) with argument _const(DEPTH_SCALE)
.br
_cmnd(Get) with argument _const(DEPTH_BIAS)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_RED_SCALE)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_RED_BIAS)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_GREEN_SCALE)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_GREEN_BIAS)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_BLUE_SCALE)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_BLUE_BIAS)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_ALPHA_SCALE)
.br
_cmnd(Get) with argument _const(POST_COLOR_MATRIX_ALPHA_BIAS)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_RED_SCALE)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_RED_BIAS)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_GREEN_SCALE)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_GREEN_BIAS)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_BLUE_SCALE)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_BLUE_BIAS)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_ALPHA_SCALE)
.br
_cmnd(Get) with argument _const(POST_CONVOLUTION_ALPHA_BIAS)
.SH SEE ALSO
_cmnd(CallList),
_cmnd(ColorTable),
_cmnd(ColorSubTable),
_cmnd(ConvolutionFilter1D),
_cmnd(ConvolutionFilter2D),
_cmnd(CopyPixels),
_cmnd(CopyTexImage1D),
_cmnd(CopyTexImage2D),
_cmnd(CopyTexSubImage1D),
_cmnd(CopyTexSubImage2D),
_cmnd(CopyTexSubImage3D),
_cmnd(DrawPixels),
_cmnd(NewList),
_cmnd(PixelMap),
_cmnd(PixelStore),
_cmnd(PixelZoom),
_cmnd(ReadPixels),
_cmnd(TexImage1D),
_cmnd(TexImage2D),
_cmnd(TexImage3D),
_cmnd(TexSubImage1D),
_cmnd(TexSubImage2D),
_cmnd(TexSubImage3D)