glPolygonStipple

  • Article

The glPolygonStipple function sets the polygon stippling pattern.

void 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.

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 xw and yw is sent to the next stage of OpenGL if and only if the (xw mod 32)th bit in the (yw 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 is the error code and its condition.

Error code Condition
GL_INVALID_OPERATION glPolygonStipple was called between a call to glBegin and the corresponding call to glEnd.

Requirements

**  Windows NT/2000:** Requires Windows NT 3.5 or later.
**  Windows 95/98:** Requires Windows 95 or later. Available as a redistributable for Windows 95.
**  Header:** Declared in Gl.h.
**  Library:** Use Opengl32.lib.

See Also

glBegin, glDrawPixels, glEnd, glLineStipple, glPixelStore, glPixelTransfer