glPixelTransferi

glPixelTransfer: man2/glPixelTransfer.xml

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:,,, and. 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. comprise a single fixed-point value, with unspecified precision to the right of the binary point. 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, 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/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.

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 are the ones that are used. They may be different from the settings when the command was compiled into the display list.