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<HTML><BODY><PRE> <STRONG>NAME</STRONG> <STRONG>fglPixelStoref,</STRONG> <STRONG>fglPixelStorei</STRONG> - set pixel storage modes <STRONG>FORTRAN</STRONG> <STRONG>SPECIFICATION</STRONG> SUBROUTINE <STRONG>fglPixelStoref</STRONG>( INTEGER*4 <EM>pname</EM>, REAL*4 <EM>param</EM> ) SUBROUTINE <STRONG>fglPixelStorei</STRONG>( INTEGER*4 <EM>pname</EM>, INTEGER*4 <EM>param</EM> ) <STRONG>PARAMETERS</STRONG> <EM>pname</EM> Specifies the symbolic name of the parameter to be set. Six values affect the packing of pixel data into memory: <STRONG>GL_PACK_SWAP_BYTES</STRONG>, <STRONG>GL_PACK_LSB_FIRST</STRONG>, <STRONG>GL_PACK_ROW_LENGTH</STRONG>, <STRONG>GL_PACK_SKIP_PIXELS</STRONG>, <STRONG>GL_PACK_SKIP_ROWS</STRONG>, and <STRONG>GL_PACK_ALIGNMENT</STRONG>. Six more affect the unpacking of pixel data <EM>from</EM> memory: <STRONG>GL_UNPACK_SWAP_BYTES</STRONG>, <STRONG>GL_UNPACK_LSB_FIRST</STRONG>, <STRONG>GL_UNPACK_ROW_LENGTH</STRONG>, <STRONG>GL_UNPACK_SKIP_PIXELS</STRONG>, <STRONG>GL_UNPACK_SKIP_ROWS</STRONG>, and <STRONG>GL_UNPACK_ALIGNMENT</STRONG>. <EM>param</EM> Specifies the value that <EM>pname</EM> is set to. <STRONG>DESCRIPTION</STRONG> <STRONG>fglPixelStore</STRONG> sets pixel storage modes that affect the operation of subsequent <STRONG>fglDrawPixels</STRONG> and <STRONG>fglReadPixels</STRONG> as well as the unpacking of polygon stipple patterns (see <STRONG>fglPolygonStipple</STRONG>), bitmaps (see <STRONG>fglBitmap</STRONG>), and texture patterns (see <STRONG>fglTexImage1D</STRONG>, <STRONG>fglTexImage2D</STRONG>, <STRONG>fglTexSubImage1D</STRONG>, and <STRONG>fglTexSubImage2D</STRONG>). <EM>pname</EM> is a symbolic constant indicating the parameter to be set, and <EM>param</EM> 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 <STRONG>fglReadPixels</STRONG> commands. They are as follows: <STRONG>GL_PACK_SWAP_BYTES</STRONG> 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 b , b , b , b , it is stored in memory as b , b , <STRONG>b</STRONG> , <STRONG>b</STRONG> i<STRONG>f</STRONG> 3 <STRONG>GL_PACK_SWAP_BYTES</STRONG> is true.3 <STRONG>GL_PACK_SWAP_BYTES</STRONG> 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 <STRONG>GL_RGB</STRONG> format pixel are always stored with red first, green second, and blue third, regardless of the value of <STRONG>GL_PACK_SWAP_BYTES</STRONG>. <STRONG>GL_PACK_LSB_FIRST</STRONG> If true, bits are ordered within a byte from least significant to most significant; otherwise, the first bit in each byte is the most significant one. This parameter is significant for bitmap data only. <STRONG>GL_PACK_ROW_LENGTH</STRONG> If greater than 0, <STRONG>GL_PACK_ROW_LENGTH</STRONG> defines the number of pixels in a row. If the first pixel of a row is placed at location p in memory, then the location of the first pixel of the next row is obtained by skipping ( |nl s<EM>></EM>a k = |<STRONG>_</STRONG>|<STRONG>___</STRONG>| s<a |s| a | ( components or indices, where n is the number of components or indices in a pixel, l is the number of pixels in a row (<STRONG>GL_PACK_ROW_LENGTH</STRONG> if it is greater than 0, the width argument to the pixel routine otherwise), a is the value of <STRONG>GL_PACK_ALIGNMENT</STRONG>, and s is the size, in bytes, of a single component (if a<s, then it is as if a=s). In the case of 1-bit values, the location of the next row is obtained by skipping k = 8a|<STRONG>__</STRONG>| |8a| components or indices. The word <EM>component</EM> in this description refers to the nonindex values red, green, blue, alpha, and depth. Storage format <STRONG>GL_RGB</STRONG>, for example, has three components per pixel: first red, then green, and finally blue. <STRONG>GL_PACK_SKIP_PIXELS</STRONG> and <STRONG>GL_PACK_SKIP_ROWS</STRONG> These values are provided as a convenience to the programmer; they provide no functionality that cannot be duplicated simply by incrementing the pointer passed to <STRONG>fglReadPixels</STRONG>. Setting <STRONG>GL_PACK_SKIP_PIXELS</STRONG> to i is equivalent to incrementing the pointer by in components or indices, where n is the number of components or indices in each pixel. Setting <STRONG>GL_PACK_SKIP_ROWS</STRONG> to j is equivalent to incrementing the pointer by jk components or indices, where k is the number of components or indices per row, as just computed in the <STRONG>GL_PACK_ROW_LENGTH</STRONG> section. <STRONG>GL_PACK_ALIGNMENT</STRONG> Specifies the alignment requirements for the start of each pixel row in memory. The allowable values are 1 (byte-alignment), 2 (rows aligned to even- numbered bytes), 4 (word-alignment), and 8 (rows start on double-word boundaries). The other six of the twelve storage parameters affect how pixel data is read from client memory. These values are significant for <STRONG>fglDrawPixels</STRONG>, <STRONG>fglTexImage1D</STRONG>, <STRONG>fglTexImage2D</STRONG>, <STRONG>fglTexSubImage1D</STRONG>, <STRONG>fglTexSubImage2D</STRONG>, <STRONG>fglBitmap</STRONG>, and <STRONG>fglPolygonStipple</STRONG>. They are as follows: <STRONG>GL_UNPACK_SWAP_BYTES</STRONG> 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 b , b , b , b , it is taken from memory as b , b , b , b 0if <STRONG>GL_UNPACK_SWAP_BYTES</STRONG> is true. 3 <STRONG>GL_UNPACK_SWAP_BYTES</STRONG> 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 <STRONG>GL_RGB</STRONG> format pixel are always stored with red first, green second, and blue third, regardless of the value of <STRONG>GL_UNPACK_SWAP_BYTES</STRONG>. <STRONG>GL_UNPACK_LSB_FIRST</STRONG> If true, bits are ordered within a byte from least significant to most significant; otherwise, the first bit in each byte is the most significant one. This is relevant only for bitmap data. <STRONG>GL_UNPACK_ROW_LENGTH</STRONG> If greater than 0, <STRONG>GL_UNPACK_ROW_LENGTH</STRONG> defines the number of pixels in a row. If the first pixel of a row is placed at location p in memory, then the location of the first pixel of the next row is obtained by skipping ( |nl s<EM>></EM>a k = |<STRONG>_</STRONG>|<STRONG>___</STRONG>| s<a |s| a | ( components or indices, where n is the number of components or indices in a pixel, l is the number of pixels in a row (<STRONG>GL_UNPACK_ROW_LENGTH</STRONG> if it is greater than 0, the width argument to the pixel routine otherwise), a is the value of <STRONG>GL_UNPACK_ALIGNMENT</STRONG>, and s is the size, in bytes, of a single component (if a<s, then it is as if a=s). In the case of 1-bit values, the location of the next row is obtained by skipping k = 8a|<STRONG>__</STRONG>| |8a| components or indices. The word <EM>component</EM> in this description refers to the nonindex values red, green, blue, alpha, and depth. Storage format <STRONG>GL_RGB</STRONG>, for example, has three components per pixel: first red, then green, and finally blue. <STRONG>GL_UNPACK_SKIP_PIXELS</STRONG> and <STRONG>GL_UNPACK_SKIP_ROWS</STRONG> These values are provided as a convenience to the programmer; they provide no functionality that cannot be duplicated by incrementing the pointer passed to <STRONG>fglDrawPixels</STRONG>, <STRONG>fglTexImage1D</STRONG>, <STRONG>fglTexImage2D</STRONG>, <STRONG>fglTexSubImage1D</STRONG>, <STRONG>fglTexSubImage2D</STRONG>, <STRONG>fglBitmap</STRONG>, or <STRONG>fglPolygonStipple</STRONG>. Setting <STRONG>GL_UNPACK_SKIP_PIXELS</STRONG> to i is equivalent to incrementing the pointer by in components or indices, where n is the number of components or indices in each pixel. Setting <STRONG>GL_UNPACK_SKIP_ROWS</STRONG> to j is equivalent to incrementing the pointer by jk components or indices, where k is the number of components or indices per row, as just computed in the <STRONG>GL_UNPACK_ROW_LENGTH</STRONG> section. <STRONG>GL_UNPACK_ALIGNMENT</STRONG> Specifies the alignment requirements for the start of each pixel row in memory. The allowable values are 1 (byte-alignment), 2 (rows aligned to even-numbered bytes), 4 (word-alignment), and 8 (rows start on double-word boundaries). The following table gives the type, initial value, and range of valid values for each storage parameter that can be set with <STRONG>fglPixelStore</STRONG>. _________________________________________________________________ | <EM>pname</EM> | <EM>type</EM> | <EM>initial</EM> <EM>value</EM> | <EM>valid</EM> <EM>range</EM> | <EM>|</EM>______________________<EM>|</EM>_________<EM>|</EM>_______________<EM>|</EM>_______________| | <STRONG>GL_PACK_SWAP_BYTES</STRONG> | boolean | false | true or false | | <STRONG>GL_PACK_LSB_FIRST</STRONG> | boolean | false | true or false | | <STRONG>GL_PACK_ROW_LENGTH</STRONG> | integer | 0 | [0,oo) | | <STRONG>GL_PACK_SKIP_ROWS</STRONG> | integer | 0 | [0,oo) | | <STRONG>GL_PACK_SKIP_PIXELS</STRONG> | integer | 0 | [0,oo) | | <STRONG>GL_PACK_ALIGNMENT</STRONG> | integer | 4 | 1, 2, 4, or 8 | <EM>|</EM>______________________<EM>|</EM>_________<EM>|</EM>_______________<EM>|</EM>_______________| |<STRONG>GL_UNPACK_SWAP_BYTES</STRONG> | boolean | false | true or false | | <STRONG>GL_UNPACK_LSB_FIRST</STRONG> | boolean | false | true or false | |<STRONG>GL_UNPACK_ROW_LENGTH</STRONG> | integer | 0 | [0,oo) | | <STRONG>GL_UNPACK_SKIP_ROWS</STRONG> | integer | 0 | [0,oo) | <EM>|</EM>______________________<EM>|</EM>_________<EM>|</EM>_______________<EM>|</EM>_______________| |<STRONG>GL_UNPACK_SKIP_PIXELS</STRONG> | integer | 0 | [0,oo) | | <STRONG>GL_UNPACK_ALIGNMENT</STRONG> | integer | 4 | 1, 2, 4, or 8 | <EM>|</EM>______________________<EM>|</EM>_________<EM>|</EM>_______________<EM>|</EM>_______________| <STRONG>fglPixelStoref</STRONG> can be used to set any pixel store parameter. If the parameter type is boolean, then if <EM>param</EM> is 0, the parameter is false; otherwise it is set to true. If <EM>pname</EM> is a integer type parameter, <EM>param</EM> is rounded to the nearest integer. Likewise, <STRONG>fglPixelStorei</STRONG> can also be used to set any of the pixel store parameters. Boolean parameters are set to false if <EM>param</EM> is 0 and true otherwise. <STRONG>NOTES</STRONG> The pixel storage modes in effect when <STRONG>fglDrawPixels</STRONG>, <STRONG>fglReadPixels</STRONG>, <STRONG>fglTexImage1D</STRONG>, <STRONG>fglTexImage2D</STRONG>, <STRONG>fglTexSubImage1D</STRONG>, <STRONG>fglTexSubImage2D</STRONG>, <STRONG>fglBitmap</STRONG>, or <STRONG>fglPolygonStipple</STRONG> is placed in a display list control the interpretation of memory data. The pixel storage modes in effect when a display list is executed are not significant. Pixel storage modes are client state and must be pushed and restored using <STRONG>fglPushClientAttrib</STRONG> and <STRONG>fglPopClientAttrib</STRONG>. <STRONG>ERRORS</STRONG> <STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>pname</EM> is not an accepted value. <STRONG>GL_INVALID_VALUE</STRONG> is generated if a negative row length, pixel skip, or row skip value is specified, or if alignment is specified as other than 1, 2, 4, or 8. <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>fglPixelStore</STRONG> is executed between the execution of <STRONG>fglBegin</STRONG> and the corresponding execution of <STRONG>fglEnd</STRONG>. <STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_PACK_SWAP_BYTES</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_PACK_LSB_FIRST</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_PACK_ROW_LENGTH</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_PACK_SKIP_ROWS</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_PACK_SKIP_PIXELS</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_PACK_ALIGNMENT</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_UNPACK_SWAP_BYTES</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_UNPACK_LSB_FIRST</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_UNPACK_ROW_LENGTH</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_UNPACK_SKIP_ROWS</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_UNPACK_SKIP_PIXELS</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_UNPACK_ALIGNMENT</STRONG> <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>fglBitmap</STRONG>, <STRONG>fglDrawPixels</STRONG>, <STRONG>fglPixelMap</STRONG>, <STRONG>fglPixelTransfer</STRONG>, <STRONG>fglPixelZoom</STRONG>, <STRONG>fglPolygonStipple</STRONG>, <STRONG>fglPushClientAttrib</STRONG>, <STRONG>fglReadPixels</STRONG>, <STRONG>fglTexImage1D</STRONG>, <STRONG>fglTexImage2D</STRONG>, <STRONG>fglTexSubImage1D</STRONG>, <STRONG>fglTexSubImage2D</STRONG></PRE></BODY></HTML>⌨️ 快捷键说明
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