- set the polygon stippling pattern
C SPECIFICATION
PARAMETERS
_param1 Specifies a pointer to a 32x32 stipple pattern
that will be unpacked from memory in the same way
that glDrawPixels unpacks pixels.
DESCRIPTION
Polygon stippling, like line stippling (see
glLineStipple), masks out certain fragments produced by
rasterization, creating a pattern. Stippling is indepen-
dent of polygon antialiasing.
_param1 is a pointer to a 32x32 stipple pattern that is
stored in memory just like the pixel data supplied to a
glDrawPixels call with height and width both equal to 32,
a pixel of GL_COLOR_INDEX, and data type of GL_BITMAP.
That is, the stipple pattern is represented as a 32x32
array of 1-bit color indices packed in unsigned bytes.
glPixelStore 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, off-
set, pixel map) are not applied to the stipple image, how-
ever.
To enable and disable polygon stippling, call glEnable and
glDisable with argument GL_POLYGON_STIPPLE. Polygon stip-
pling is initially disabled. If it's enabled, a rasterized
polygon fragment with window coordinates xw and yw is sent
to the next stage of the GL if and only if the (xwmod32)th
bit in the (ywmod32)th row of the stipple pattern is 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 glPolygonStipple is
executed between the execution of glBegin and the corre-
sponding execution of glEnd.
ASSOCIATED GETS
glGetPolygonStipple
glIsEnabled with argument GL_POLYGON_STIPPLE
SEE ALSO
glDrawPixels, glLineStipple, glPixelStore, glPixelTransfer
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