HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 333

P glPixelTransfer Chapter 14 glPixelTransfer glPixelTransferf, glPixelTransferi: set pixel transfer modes. C Specification void glPixelTransferf( GLenum pname, GLfloat param) void glPixelTransferi( GLenum pname, GLint param) Parameters pname param 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. 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, glDrawPixels, glReadPixels, glTexImage1D, glTexImage2D, glTexSubImage1D, and glTexSubImage2D commands. 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, and glReadPixels), or unpacked from client memory (glDrawPixels, glTexImage1D, glTexImage2D, glTexSubImage1D, and glTexSubImage2D). 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 333