glPixelMapusv

glPixelMap: man2/glPixelMap.xml

glPixelMap sets up translation tables, or, used by glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glDrawPixels, glReadPixels, glTexImage1D, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, and glTexSubImage3D. Additionally, if the ARB_imaging subset is supported, the routines glColorTable, glColorSubTable, glConvolutionFilter1D, glConvolutionFilter2D, glHistogram, glMinmax, and glSeparableFilter2D. Use of these maps is described completely in the glPixelTransfer reference page, and partly in the reference pages for the pixel and texture image commands. Only the specification of the maps is described in this reference page. map is a symbolic map name, indicating one of ten maps to set. mapsize specifies the number of entries in the map, and values is a pointer to an array of mapsize map values. If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer ) while a pixel transfer map is specified, values is treated as a byte offset into the buffer object's data store. The ten maps are as follows: The entries in a map can be specified as single-precision floating-point numbers, unsigned short integers, or unsigned int integers. Maps that store color component values (all but GL_PIXEL_MAP_I_TO_I and GL_PIXEL_MAP_S_TO_S ) retain their values in floating-point format, with unspecified mantissa and exponent sizes. Floating-point values specified by glPixelMapfv are converted directly to the internal floating-point format of these maps, then clamped to the range [0,1]. Unsigned integer values specified by glPixelMapusv and glPixelMapuiv are converted linearly such that the largest representable integer maps to 1.0, and 0 maps to 0.0. Maps that store indices, GL_PIXEL_MAP_I_TO_I and GL_PIXEL_MAP_S_TO_S, retain their values in fixed-point format, with an unspecified number of bits to the right of the binary point. Floating-point values specified by glPixelMapfv are converted directly to the internal fixed-point format of these maps. Unsigned integer values specified by glPixelMapusv and glPixelMapuiv specify integer values, with all 0's to the right of the binary point. The following table shows the initial sizes and values for each of the maps. Maps that are indexed by either color or stencil indices must have mapsize = 2 n for some n or the results are undefined. The maximum allowable size for each map depends on the implementation and can be determined by calling glGet with argument GL_MAX_PIXEL_MAP_TABLE. The single maximum applies to all maps; it is at least 32. map Lookup Index Lookup Value Initial Size Initial Value GL_PIXEL_MAP_I_TO_I color index color index 1 0 GL_PIXEL_MAP_S_TO_S stencil index stencil index 1 0 GL_PIXEL_MAP_I_TO_R color index R 1 0 GL_PIXEL_MAP_I_TO_G color index G 1 0 GL_PIXEL_MAP_I_TO_B color index B 1 0 GL_PIXEL_MAP_I_TO_A color index A 1 0 GL_PIXEL_MAP_R_TO_R R R 1 0 GL_PIXEL_MAP_G_TO_G G G 1 0 GL_PIXEL_MAP_B_TO_B B B 1 0 GL_PIXEL_MAP_A_TO_A A A 1 0