Parameters

Description

Polygon stippling, like line stippling (see glLineStipple), masks out certain fragments produced by rasterization, creating a pattern. Stippling is independent of polygon antialiasing.

pattern is a pointer to a 32 × 32 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 format of GL_COLOR_INDEX, and data type of GL_BITMAP. That is, the stipple pattern is represented as a 32 × 32 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, offset, pixel map) are not applied to the stipple image, however.

If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer) while a stipple pattern is specified, pattern is treated as a byte offset into the buffer object's data store.

To enable and disable polygon stippling, call glEnable and glDisable with argument GL_POLYGON_STIPPLE. Polygon stippling is initially disabled. If it's enabled, a rasterized polygon fragment with window coordinates x w and y w is sent to the next stage of the GL if and only if the ( x w % 32 )th bit in the ( y w % 32 )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 a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and the buffer object's data store is currently mapped.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and the data would be unpacked from the buffer object such that the memory reads required would exceed the data store size.

GL_INVALID_OPERATION is generated if glPolygonStipple is executed between the execution of glBegin and the corresponding execution of glEnd.

Associated Gets

glGetPolygonStipple

glIsEnabled with argument GL_POLYGON_STIPPLE

glGet with argument GL_PIXEL_UNPACK_BUFFER_BINDING

See Also

glDrawPixels, glLineStipple, glPixelStore, glPixelTransfer

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.