glPolygonStipple
[New
- Windows 95, OEM Service Release 2]
The glPolygonStipple
function sets the polygon stippling pattern.
void glPolygonStipple(
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const GLubyte *mask |
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); |
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Parameters
mask
A pointer to
a 32x32 stipple pattern that will be unpacked from memory in the same way that glDrawPixels unpacks pixels.
Remarks
The glPolygonStipple
function sets the polygon stippling pattern. Polygon stippling, like line
stippling (see glLineStipple),
masks out certain fragments produced by rasterization, creating a pattern.
Stippling is independent of polygon antialiasing.
The mask
parameter is a pointer to a 32x32 stipple pattern that is stored in memory just
like the pixel data supplied to glDrawPixels 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 32x32
array of 1-bit color indexes packed in unsigned bytes. The glPixelStore
function parameters, such as GL_UNPACK_SWAP_BYTES and GL_UNPACK_LSB_FIRST,
affect the assembling of the bits into a stipple pattern. Pixel transfer
operations (shift, offset, and pixel map) are not applied to the stipple image,
however.
Polygon
stippling is enabled and disabled with glEnable and glDisable,
using argument GL_POLYGON_STIPPLE. If enabled, a rasterized polygon fragment with
window coordinates x (w) and y (w) is sent to the next stage of OpenGL if and
only if the (x (w) mod 32)th bit
in the (y (w) mod 32)th row
of the stipple pattern is one. When polygon stippling is disabled, it is as if
the stipple pattern were all ones.
The following
functions retrieve information related to glPolygonStipple:
glGetPolygonStipple
glIsEnabled with argument GL_POLYGON_STIPPLE
Error Codes
The following
are the error codes generated and their conditions.
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Error
Code |
Condition |
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GL_INVALID_OPERATION
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glPolygonStipple was called between a call to glBegin and the
corresponding call to glEnd. |
See Also