OpenGL C bindings library: **libGL.a**

voidglPixelTransferf(GLenumpName,GLfloatParameter)

voidglPixelTransferi(GLenumpName,GLintParameter)

pName |
Specifies the symbolic name of the pixel transfer parameter to be set. Must be one of the following: |

Parameter |
Specifies the value to which pName is set. |

The **glPixelTransfer** subroutine sets pixel transfer modes that affect the operation of subsequent **glDrawPixels**, **glReadPixels**, **glCopyPixels**, **glCopyTexImage1D**, **glCopyTexImage2D**, **glCopyTexSubImage1D**, **glCopyTexSubImage2D**, **glCopyTexSubImage3DEXT**, **glTexImage1D**, **glTexImage2D**, **glTexImage3DEXT**,** glTexSubImage1D**,** glTexSubImage2D**, and **glTexSubImage3DEXT **subroutines.
The algorithms that are specified by pixel transfer modes operate on pixels after they are read from the frame buffer (**glReadPixels** and **glCopyPixels**) or unpacked from client memory (**glDrawPixels**, **glReadPixels**, **glCopyPixels**, **glCopyTexImage1D**, **glCopyTexImage2D**, **glCopyTexSubImage1D**, **glCopyTexSubImage2D**, **glCopyTexSubImage3DEXT**, **glTexImage1D**, **glTexImage2D**, **glTexImage3DEXT**,** glTexSubImage1D**,** glTexSubImage2D**, and **glTexSubImage3DEXT **subroutines). 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 control the unpacking of pixels being read from client memory and the packing of pixels being written back into client memory. (See the **glPixelStore** subroutine for information on setting pixel storage modes.)

Pixel transfer operations handle four fundamental pixel types: *color*, *color index*, *depth*, and *stencil*. Color pixels are made up of four floating-point values with unspecified mantissa and exponent sizes, scaled such that 0.0 represents 0 (zero) intensity and 1.0 represents full intensity. Color indexes 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:

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 Value |
Valid Range |

GL_MAP_COLOR |
Boolean | False | True or False |

GL_MAP_STENCIL |
Boolean | False | True or False |

GL_INDEX_SHIFT |
integer | 0 | (-infinity,+infinity) |

GL_INDEX_OFFSET |
integer | 0 | (-infinity,+infinity) |

GL_RED_SCALE |
float | 1.0 | (-infinity,+infinity) |

GL_GREEN_SCALE |
float | 1.0 | (-infinity,+infinity) |

GL_BLUE_SCALE |
float | 1.0 | (-infinity,+infinity) |

GL_ALPHA_SCALE |
float | 1.0 | (-infinity,+infinity) |

GL_DEPTH_SCALE |
float | 1.0 | (-infinity,+infinity) |

GL_RED_BIAS |
float | 0.0 | (-infinity,+infinity) |

GL_GREEN_BIAS |
float | 0.0 | (-infinity,+infinity) |

GL_BLUE_BIAS |
float | 0.0 | (-infinity,+infinity) |

GL_ALPHA_BIAS |
float | 0.0 | (-infinity,+infinity) |

GL_DEPTH_BIAS |
float | 0.0 | (-infinity,+infinity) |

The **glPixelTransferf** subroutine can be used to set any pixel transfer parameter. If the parameter type is Boolean, 0.0 implies False and any other value implies True. If *pName* is an integer parameter, *Parameter* 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 *Parameter* is 0 and True otherwise. *Parameter* is converted to floating-point format before being assigned to real-valued parameters.

If a **glDrawPixels**, **glReadPixels**, **glCopyPixels**, **glTexImage1D**, or **glTexImage2D** subroutine is placed in a display list (see the **glNewList** subroutine and the **glCallList** subroutine for information about display lists), 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.

GL_INVALID_ENUM |
pName is not an accepted value. |

GL_INVALID_OPERATION |
The glPixelTransfer subroutine is called between a call to glBegin and the corresponding call to glEnd. |

Associated gets for the **glPixelTransfer** subroutine are as follows. (See the **glGet** subroutine for more information.)

**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**.

/usr/include/GL/gl.h |
Contains C language constants, variable type definitions, and ANSI function prototypes for OpenGL. |

The **glBegin **or **glEnd** subroutine, **glCallList** subroutine, **glCopyPixels** subroutine, **glCopyTexImage1D** subroutine, **glCopyTexImage2D** subroutine,
**glCopyTexSubImage1D** subroutine, **glCopyTexSubImage2D** subroutine, **glCopyTexSubImage3DEXT** subroutine, **glDrawPixels** subroutine, **glNewList** subroutine, **glPixelMap** subroutine, **glPixelStore** subroutine, **glPixelZoom** subroutine,
**glReadPixels** subroutine, **glTexImage1D** subroutine, **glTexImage2D** subroutine, **glTexImage3DEXT** subroutine, **glTexSubImage1D** subroutine, **glTexSubImage2D** subroutine, **glTexSubImage3DEXT** subroutine, .