These constants define a graphics tool for vector data drawing.

Values:

IG_VECT_GRAPH_OPENGL	Drawing with OpenGL.
IG_VECT_GRAPH_DIRECT3D	Drawing with Direct3D.
IG_VECT_GRAPH_AUTO	The type of graphics (OpenGL or Direct3D) is detected automatically.
IG_VECT_GRAPH_WINAPI	This value has been deprecated and will be removed from the public API in a future release.