glEdgeFlag, glEdgeFlagv

The glEdgeFlag and glEdgeFlagv functions flag edges as either boundary or nonboundary.

void glEdgeFlag(
  GLboolean flag   
);
 

Parameters

flag

In glEdgeFlag, specifies the current edge flag value, either TRUE or FALSE.

void glEdgeFlagv(
  const GLboolean * flag   
);
 

Parameters

flag

In glEdgeFlagv, specifies a pointer to an array that contains a single Boolean element, which replaces the current edge flag value.

Remarks

Each vertex of a polygon, separate triangle, or separate quadrilateral specified between a glBegin/glEnd pair is marked as the start of either a boundary or nonboundary edge. If the current edge flag is TRUE when the vertex is specified, the vertex is marked as the start of a boundary edge. If the current edge flag is FALSE, the vertex is marked as the start of a nonboundary edge. The glEdgeFlag function sets the edge flag to TRUE if flag is nonzero, FALSE otherwise.

The vertices of connected triangles and connected quadrilaterals are always marked as boundary, regardless of the value of the edge flag.

Boundary and nonboundary edge flags on vertices are significant only if GL_POLYGON_MODE is set to GL_POINT or GL_LINE. See glPolygonMode.

Initially, the edge flag bit is TRUE.

The current edge flag can be updated at any time. In particular, glEdgeFlag can be called between a call to glBegin and the corresponding call to glEnd.

The following function retrieves information related to the glEdgeFlag function:

glGet with argument GL_EDGE_FLAG

QuickInfo

  Windows NT: Use version 3.5 and later.
  Windows: Use Windows 95 and later.
  Windows CE: Unsupported.
  Header: Declared in gl.h.
  Import Library: Link with opengl32.lib.

See Also

glBegin, glEnd, glGet, glPolygonMode