glPolygonStipple function

The glPolygonStipple function sets the polygon stippling pattern.

Syntax

void WINAPI glPolygonStipple(
   const GLubyte *mask
);

Parameters

mask

A pointer to a 32x32 stipple pattern that will be unpacked from memory in the same way that glDrawPixels unpacks pixels.

Return value

This function does not return a value.

Error codes

The following error code can be retrieved by the glGetError function.

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

Requirements

See also

glBegin

glDrawPixels

glEnd

glLineStipple

glPixelStore

glPixelTransfer