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GLPIXELTRANSFER(3G)		 OpenGL Manual		   GLPIXELTRANSFER(3G)

NAME
       glPixelTransfer - set pixel transfer modes

C SPECIFICATION
       void glPixelTransferf(GLenum pname, GLfloat param);

       void glPixelTransferi(GLenum pname, GLint param);

PARAMETERS
       pname
	   Specifies the symbolic name of the pixel transfer parameter to be
	   set. Must be one of the following: GL_MAP_COLOR, GL_MAP_STENCIL,
	   GL_INDEX_SHIFT, GL_INDEX_OFFSET, GL_RED_SCALE, GL_RED_BIAS,
	   GL_GREEN_SCALE, GL_GREEN_BIAS, GL_BLUE_SCALE, GL_BLUE_BIAS,
	   GL_ALPHA_SCALE, GL_ALPHA_BIAS, GL_DEPTH_SCALE, or GL_DEPTH_BIAS.

	   Additionally, if the ARB_imaging extension is supported, the
	   following symbolic names are accepted:
	   GL_POST_COLOR_MATRIX_RED_SCALE, GL_POST_COLOR_MATRIX_GREEN_SCALE,
	   GL_POST_COLOR_MATRIX_BLUE_SCALE, GL_POST_COLOR_MATRIX_ALPHA_SCALE,
	   GL_POST_COLOR_MATRIX_RED_BIAS, GL_POST_COLOR_MATRIX_GREEN_BIAS,
	   GL_POST_COLOR_MATRIX_BLUE_BIAS, GL_POST_COLOR_MATRIX_ALPHA_BIAS,
	   GL_POST_CONVOLUTION_RED_SCALE, GL_POST_CONVOLUTION_GREEN_SCALE,
	   GL_POST_CONVOLUTION_BLUE_SCALE, GL_POST_CONVOLUTION_ALPHA_SCALE,
	   GL_POST_CONVOLUTION_RED_BIAS, GL_POST_CONVOLUTION_GREEN_BIAS,
	   GL_POST_CONVOLUTION_BLUE_BIAS, and GL_POST_CONVOLUTION_ALPHA_BIAS.

       param
	   Specifies the value that pname is set to.

DESCRIPTION
       glPixelTransfer sets pixel transfer modes that affect the operation of
       subsequent glCopyPixels(), glCopyTexImage1D(), glCopyTexImage2D(),
       glCopyTexSubImage1D(), glCopyTexSubImage2D(), glCopyTexSubImage3D(),
       glDrawPixels(), glReadPixels(), glTexImage1D(), glTexImage2D(),
       glTexImage3D(), glTexSubImage1D(), glTexSubImage2D(), and
       glTexSubImage3D() commands. Additionally, if the ARB_imaging subset is
       supported, the routines glColorTable(), glColorSubTable(),
       glConvolutionFilter1D(), glConvolutionFilter2D(), glHistogram(),
       glMinmax(), and glSeparableFilter2D() are also affected. The algorithms
       that are specified by pixel transfer modes operate on pixels after they
       are read from the frame buffer (glCopyPixels() glCopyTexImage1D(),
       glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(),
       glCopyTexSubImage3D(), and glReadPixels()), or unpacked from client
       memory (glDrawPixels(), glTexImage1D(), glTexImage2D(), glTexImage3D(),
       glTexSubImage1D(), glTexSubImage2D(), and glTexSubImage3D()). 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 glPixelStore()) control the unpacking of pixels
       being read from client memory and the packing of pixels being written
       back into client memory.

       Pixel transfer operations handle four fundamental pixel types: color,
       color index, depth, and stencil.	 Color 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.  Color indices comprise a single fixed-point value, with
       unspecified precision to the right of the binary point.	Depth 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, stencil pixels comprise a single fixed-point value, with
       unspecified precision to the right of the binary point.

       The pixel transfer operations performed on the four basic pixel types
       are as follows:

       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 GL_RED_SCALE, then added to GL_RED_BIAS; the green
	   component is multiplied by GL_GREEN_SCALE, then added to
	   GL_GREEN_BIAS; the blue component is multiplied by GL_BLUE_SCALE,
	   then added to GL_BLUE_BIAS; and the alpha component is multiplied
	   by GL_ALPHA_SCALE, then added to GL_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
	   glPixelTransfer.

	   If GL_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 GL_PIXEL_MAP_R_TO_R_SIZE, then replaced
	   by the contents of GL_PIXEL_MAP_R_TO_R indexed by itself. The green
	   component is scaled by GL_PIXEL_MAP_G_TO_G_SIZE, then replaced by
	   the contents of GL_PIXEL_MAP_G_TO_G indexed by itself. The blue
	   component is scaled by GL_PIXEL_MAP_B_TO_B_SIZE, then replaced by
	   the contents of GL_PIXEL_MAP_B_TO_B indexed by itself. And the
	   alpha component is scaled by GL_PIXEL_MAP_A_TO_A_SIZE, then
	   replaced by the contents of GL_PIXEL_MAP_A_TO_A indexed by itself.
	   All components taken from the maps are then clamped to the range 0
	   1.  GL_MAP_COLOR is specified with glPixelTransfer. The contents of
	   the various maps are specified with glPixelMap().

	   If the ARB_imaging extension is supported, each of the four color
	   components may be scaled and biased after transformation by the
	   color matrix. That is, the red component is multiplied by
	   GL_POST_COLOR_MATRIX_RED_SCALE, then added to
	   GL_POST_COLOR_MATRIX_RED_BIAS; the green component is multiplied by
	   GL_POST_COLOR_MATRIX_GREEN_SCALE, then added to
	   GL_POST_COLOR_MATRIX_GREEN_BIAS; the blue component is multiplied
	   by GL_POST_COLOR_MATRIX_BLUE_SCALE, then added to
	   GL_POST_COLOR_MATRIX_BLUE_BIAS; and the alpha component is
	   multiplied by GL_POST_COLOR_MATRIX_ALPHA_SCALE, then added to
	   GL_POST_COLOR_MATRIX_ALPHA_BIAS. After all four color components
	   are scaled and biased, each is clamped to the range 0 1.

	   Similarly, if the ARB_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 GL_POST_CONVOLUTION_RED_SCALE, then added to
	   GL_POST_CONVOLUTION_RED_BIAS; the green component is multiplied by
	   GL_POST_CONVOLUTION_GREEN_SCALE, then added to
	   GL_POST_CONVOLUTION_GREEN_BIAS; the blue component is multiplied by
	   GL_POST_CONVOLUTION_BLUE_SCALE, then added to
	   GL_POST_CONVOLUTION_BLUE_BIAS; and the alpha component is
	   multiplied by GL_POST_CONVOLUTION_ALPHA_SCALE, then added to
	   GL_POST_CONVOLUTION_ALPHA_BIAS. After all four color components are
	   scaled and biased, each is clamped to the range 0 1.

       Color index
	   Each color index is shifted left by GL_INDEX_SHIFT bits; any bits
	   beyond the number of fraction bits carried by the fixed-point index
	   are filled with zeros. If GL_INDEX_SHIFT is negative, the shift is
	   to the right, again zero filled. Then GL_INDEX_OFFSET is added to
	   the index.  GL_INDEX_SHIFT and GL_INDEX_OFFSET are specified with
	   glPixelTransfer.

	   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 GL_COLOR_INDEX format, the pixels continue to be
	   treated as indices. If GL_MAP_COLOR is true, each index is masked
	   by 2 n - 1, where n is GL_PIXEL_MAP_I_TO_I_SIZE, then replaced by
	   the contents of GL_PIXEL_MAP_I_TO_I indexed by the masked value.
	   GL_MAP_COLOR is specified with glPixelTransfer. The contents of the
	   index map is specified with glPixelMap().

	   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
	   GL_COLOR_INDEX, the pixels are converted from indices to colors by
	   referencing the four maps GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G,
	   GL_PIXEL_MAP_I_TO_B, and GL_PIXEL_MAP_I_TO_A. Before being
	   dereferenced, the index is masked by 2 n - 1, where n is
	   GL_PIXEL_MAP_I_TO_R_SIZE for the red map, GL_PIXEL_MAP_I_TO_G_SIZE
	   for the green map, GL_PIXEL_MAP_I_TO_B_SIZE for the blue map, and
	   GL_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 glPixelMap().

       Depth
	   Each depth value is multiplied by GL_DEPTH_SCALE, added to
	   GL_DEPTH_BIAS, then clamped to the range 0 1.

       Stencil
	   Each index is shifted GL_INDEX_SHIFT bits just as a color index is,
	   then added to GL_INDEX_OFFSET. If GL_MAP_STENCIL is true, each
	   index is masked by 2 n - 1, where n is GL_PIXEL_MAP_S_TO_S_SIZE,
	   then replaced by the contents of GL_PIXEL_MAP_S_TO_S indexed by the
	   masked value.

       The following table gives the type, initial value, and range of valid
       values for each of the pixel transfer parameters that are set with
       glPixelTransfer.

       ┌─────────────────────────────────┬──────────────────────────────┬─────────────────────────────────┬───────────────────────────────┐
       │				 │				│				  │				  │
       │			pname	 │			   Type │			  Initial │			    Valid │
       │				 │				│ Value				  │ Range			  │
       │				 │				│				  │				  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_MAP_COLOR			 │	     boolean		│	       false		  │	     true/false		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_MAP_STENCIL			 │	     boolean		│	       false		  │	     true/false		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_INDEX_SHIFT			 │	     integer		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_INDEX_OFFSET			 │	     integer		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_RED_SCALE			 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_GREEN_SCALE			 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_BLUE_SCALE			 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_ALPHA_SCALE			 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_DEPTH_SCALE			 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_RED_BIAS			 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_GREEN_BIAS			 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_BLUE_BIAS			 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_ALPHA_BIAS			 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_DEPTH_BIAS			 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_RED_SCALE	 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_GREEN_SCALE │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_BLUE_SCALE	 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_ALPHA_SCALE │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_RED_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_GREEN_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_BLUE_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_COLOR_MATRIX_ALPHA_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_RED_SCALE	 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_GREEN_SCALE	 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_BLUE_SCALE	 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_ALPHA_SCALE	 │	      float		│		 1		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_RED_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_GREEN_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_BLUE_BIAS	 │	      float		│		 0		  │		  -		  │
       ├─────────────────────────────────┼──────────────────────────────┼─────────────────────────────────┼───────────────────────────────┤
       │GL_POST_CONVOLUTION_ALPHA_BIAS	 │	      float		│		 0		  │		  -		  │
       └─────────────────────────────────┴──────────────────────────────┴─────────────────────────────────┴───────────────────────────────┘

       glPixelTransferf 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 pname is an integer parameter, param is rounded to the
       nearest integer.

       Likewise, glPixelTransferi can be used to set any of the pixel transfer
       parameters. Boolean parameters are set to false if param is 0 and to
       true otherwise.	param is converted to floating point before being
       assigned to real-valued parameters.

NOTES
       If a glColorTable(), glColorSubTable(), glConvolutionFilter1D(),
       glConvolutionFilter2D(), glCopyPixels(), glCopyTexImage1D(),
       glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(),
       glCopyTexSubImage3D(), glDrawPixels(), glReadPixels(),
       glSeparableFilter2D(), glTexImage1D(), glTexImage2D(), glTexImage3D(),
       glTexSubImage1D(), glTexSubImage2D(), or glTexSubImage3D() command is
       placed in a display list (see glNewList() and glCallList()), the pixel
       transfer mode settings in effect when the display list is executed are
       the ones that are used. They may be different from the settings when
       the command was compiled into the display list.

ERRORS
       GL_INVALID_ENUM is generated if pname is not an accepted value.

       GL_INVALID_OPERATION is generated if glPixelTransfer is executed
       between the execution of glBegin() and the corresponding execution of
       glEnd().

ASSOCIATED GETS
       glGet() with argument GL_MAP_COLOR

       glGet() with argument GL_MAP_STENCIL

       glGet() with argument GL_INDEX_SHIFT

       glGet() with argument GL_INDEX_OFFSET

       glGet() with argument GL_RED_SCALE

       glGet() with argument GL_RED_BIAS

       glGet() with argument GL_GREEN_SCALE

       glGet() with argument GL_GREEN_BIAS

       glGet() with argument GL_BLUE_SCALE

       glGet() with argument GL_BLUE_BIAS

       glGet() with argument GL_ALPHA_SCALE

       glGet() with argument GL_ALPHA_BIAS

       glGet() with argument GL_DEPTH_SCALE

       glGet() with argument GL_DEPTH_BIAS

       glGet() with argument GL_POST_COLOR_MATRIX_RED_SCALE

       glGet() with argument GL_POST_COLOR_MATRIX_RED_BIAS

       glGet() with argument GL_POST_COLOR_MATRIX_GREEN_SCALE

       glGet() with argument GL_POST_COLOR_MATRIX_GREEN_BIAS

       glGet() with argument GL_POST_COLOR_MATRIX_BLUE_SCALE

       glGet() with argument GL_POST_COLOR_MATRIX_BLUE_BIAS

       glGet() with argument GL_POST_COLOR_MATRIX_ALPHA_SCALE

       glGet() with argument GL_POST_COLOR_MATRIX_ALPHA_BIAS

       glGet() with argument GL_POST_CONVOLUTION_RED_SCALE

       glGet() with argument GL_POST_CONVOLUTION_RED_BIAS

       glGet() with argument GL_POST_CONVOLUTION_GREEN_SCALE

       glGet() with argument GL_POST_CONVOLUTION_GREEN_BIAS

       glGet() with argument GL_POST_CONVOLUTION_BLUE_SCALE

       glGet() with argument GL_POST_CONVOLUTION_BLUE_BIAS

       glGet() with argument GL_POST_CONVOLUTION_ALPHA_SCALE

       glGet() with argument GL_POST_CONVOLUTION_ALPHA_BIAS

SEE ALSO
       glCallList(), glColorTable(), glColorSubTable(),
       glConvolutionFilter1D(), glConvolutionFilter2D(), glCopyPixels(),
       glCopyTexImage1D(), glCopyTexImage2D(), glCopyTexSubImage1D(),
       glCopyTexSubImage2D(), glCopyTexSubImage3D(), glDrawPixels(),
       glNewList(), glPixelMap(), glPixelStore(), glPixelZoom(),
       glReadPixels(), glTexImage1D(), glTexImage2D(), glTexImage3D(),
       glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D()

COPYRIGHT
       Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
       under the SGI Free Software B License. For details, see
       http://oss.sgi.com/projects/FreeB/.

AUTHORS
       opengl.org

opengl.org			  03/16/2013		   GLPIXELTRANSFER(3G)

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