endqstrip(3G)							 endqstrip(3G)

NAME    [Toc]    [Back]

     bgnqstrip,	endqstrip - delimit the	vertices of a quadrilateral strip

C SPECIFICATION    [Toc]    [Back]

     void bgnqstrip()

     void endqstrip()

DESCRIPTION    [Toc]    [Back]

     Vertices specified	between	bgnqstrip and endqstrip	are used to define a
     strip of quadrilaterals.  The graphics pipe maintains three vertex
     registers.	 The first, second, and	third vertices are loaded into the
     registers,	but no quadrilateral is	drawn until the	system executes	the
     fourth vertex routine. Upon executing the fourth vertex routine, the
     system draws a quadrilateral through the vertices,	then replaces the two
     oldest vertices with the third and	fourth vertices.

     For each new pair of vertex routines, the system draws a quadrilateral
     through two new vertices and the two older	stored vertices, then replaces
     the older stored vertices with the	two new	vertices.

     The quadrilaterals	are drawn as though each quadrilateral was an
     independent polygon with vertex order (n, n+1, n+3, n+2).

     If	the quadrilateral projects a self-intersecting polygon,	its rendering
     will be hardware-specific.	 The Graphics Library only guarantees that
     pixels outside of the convex hull will not	be modified.

     Between bgnqstrip and endqstrip you can issue the following Graphics
     Library routines:	c, color, cpack, lmbind, lmcolor, lmdef, n, RGBcolor,
     t,	and v.	Use lmdef and lmbind only to respecify materials and their
     properties.

     There is no limit to the number of	vertices that can be specified between
     bgnqstrip and endqstrip. The result is undefined, however,	if an odd
     number of vertices	are specified, or if fewer than	four vertices are
     specified.

     By	default, quadrilateral vertices	are forced to the nearest pixel	center
     prior to scan conversion.	Quadrilateral accuracy is improved when	this
     coercion is defeated with the subpixel command.  Subpixel vertex
     positioning is especially important when quadrilaterals are scan
     converted with antialiasing enabled (see polysmooth).

     After endqstrip, the current graphics position is undefined.

     See the Graphics Library Programmer's Guide for examples.

SEE ALSO    [Toc]    [Back]

     backface, c, concave, frontface, polymode,	polysmooth, scrsubdivide,
     defpattern, shademodel, subpixel, v




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endqstrip(3G)							 endqstrip(3G)

NOTE    [Toc]    [Back]

     IRIS-4D VGX models	use vertex normals to improve the shading quality of
     quadrilaterals, regardless	of whether lighting is enabled.

     On	some systems quadrilateral strips are decomposed into triangles	prior
     to	shading	and scan conversion.

     See the section, "2.1.4 Polygons,"	in the Graphics	Library	Programmer's
     Guide for a discussion on the handling of non-coplanar and/or selfintersecting
 polygons.

     See the section, "2.1.6 Meshes," in the Graphics Library Programmer's
     Guide for a discussion on the order of the	vertices when a	q-strip	is
     decomposed	into its equivalent t-mesh.

     On	Impact and Infinite Reality lmcolor cannot be called between bgnqstrip
     and endqstrip


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