HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 328

P glPixelStore glPixelStore glPixelStoref, glPixelStorei: set pixel storage modes. C Specification void glPixelStoref( GLenum pname, GLfloat param) void glPixelStorei( GLenum pname, GLint param) Parameters pname param Specifies the symbolic name of the parameter to be set. Six values affect the packing of pixel data into memory: GL_PACK_SWAP_BYTES, GL_PACK_LSB_FIRST, GL_PACK_ROW_LENGTH, GL_PACK_SKIP_PIXELS, GL_PACK_SKIP_ROWS, and GL_PACK_ALIGNMENT. Six more affect the unpacking of pixel data from memory: GL_UNPACK_SWAP_BYTES, GL_UNPACK_LSB_FIRST, GL_UNPACK_ROW_LENGTH, GL_UNPACK_SKIP_PIXELS, GL_UNPACK_SKIP_ROWS, and GL_UNPACK_ALIGNMENT. Specifies the value that pname is set to. Description glPixelStore sets pixel storage modes that affect the operation of subsequent glDrawPixels and glReadPixels as well as the unpacking of polygon stipple patterns (see glPolygonStipple), bitmaps (see glBitmap), and texture patterns (see glTexImage1D, glTexImage2D, glTexSubImage1D, and glTexSubImage2D). pname is a symbolic constant indicating the parameter to be set, and param is the new value. Six of the twelve storage parameters affect how pixel data is returned to client memory, and are therefore significant only for glReadPixels commands. They are as follows: GL_PACK_SWAP_BYTES If true, byte ordering for multibyte color components, depth components, color indices, or stencil indices is reversed. That is, if a four-byte component consists of bytes b0, b1, b2, b3, it is stored in memory as b3, b2, b1, b0 if GL_PACK_SWAP_BYTES is true. GL_PACK_SWAP_BYTES has no effect on the memory order of components within a pixel, only on the order of bytes within components or indices. For example, the three components of a GL_RGB format pixel are always stored with red first, green second, and blue third, regardless of the value of GL_PACK_SWAP_BYTES. GL_PACK_LSB_FIRST 328 Chapter 14