fglPolygonStipple(3G) OpenGL Reference fglPolygonStipple(3G)NAME
fglPolygonStipple - set the polygon stippling pattern
FORTRAN SPECIFICATION
SUBROUTINE fglPolygonStipple( CHARACTER*256 mask )
PARAMETERS
mask Specifies a pointer to a 32 x 32 stipple pattern that will be
unpacked from memory in the same way that fglDrawPixels unpacks
pixels.
DESCRIPTION
Polygon stippling, like line stippling (see fglLineStipple), masks out
certain fragments produced by rasterization, creating a pattern.
Stippling is independent of polygon antialiasing.
mask is a pointer to a 32 x 32 stipple pattern that is stored in memory
just like the pixel data supplied to a fglDrawPixels call with height and
width both equal to 32, a pixel format of GL_COLOR_INDEX, and data type
of GL_BITMAP. That is, the stipple pattern is represented as a 32 x 32
array of 1-bit color indices packed in unsigned bytes. fglPixelStore
parameters like GL_UNPACK_SWAP_BYTES and GL_UNPACK_LSB_FIRST affect the
assembling of the bits into a stipple pattern. Pixel transfer operations
(shift, offset, pixel map) are not applied to the stipple image, however.
To enable and disable polygon stippling, call fglEnable and fglDisable
with argument GL_POLYGON_STIPPLE. Polygon stippling is initially
disabled. If it's enabled, a rasterized polygon fragment with window
coordinates x and y is sent to the next stage of the GL if and only if
w w
the (x mod 32)th bit in the (y mod 32)th row of the stipple pattern is
w w
1 (one). When polygon stippling is disabled, it is as if the stipple
pattern consists of all 1's.
ERRORS
GL_INVALID_OPERATION is generated if fglPolygonStipple is executed
between the execution of fglBegin and the corresponding execution of
fglEnd.
ASSOCIATED GETS
fglGetPolygonStipple
fglIsEnabled with argument GL_POLYGON_STIPPLE
SEE ALSO
fglDrawPixels, fglLineStipple, fglPixelStore, fglPixelTransfer
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