gletwistextrusion(3gle) [debian man page]

gleTwistExtrusion(3GLE) 						GLE						   gleTwistExtrusion(3GLE)

NAME

       gleTwistExtrusion - Extrude arbitrary 2D contour along arbitrary 3D path, specifying local rotations (twists).

SYNTAX

       void gleTwistExtrusion (int ncp,
		       gleDouble contour[][2],
		       gleDouble cont_normal[][2],
		       gleDouble up[3],
		       int npoints,
		       gleDouble point_array[][3],
		       float color_array[][3],
		       gleDouble twist_array[]);

ARGUMENTS

       ncp	 number of contour points

       contour	 2D contour

       cont_normal
		 2D contour normals

       up	 up vector for contour

       npoints	 numpoints in poly-line

       point_array
		 polyline vertices

       color_array
		 colors at polyline verts

       twist_array
		 contour twists (in degrees)

DESCRIPTION

       Extrude	arbitrary  2D contour along arbitrary 3D path, specifying local rotations (twists). As the contour is extruded, it will be twisted
       by the amount specified in the array "twist_array". The angles are measured in degrees, and the rotation is about the origin of the contour
       coordinate system.

       The argument "contour" specifies the 2D contour to be extruded, while the argument "point_array" specifies the path along which to extrude.
       The vector "up" defines the orientation of the contour y-axis in real 3D space.

       Note that neither the very first segment, nor the very last segment are drawn. The first and last segments serve only to define	the  angle
       of the join at the very ends of the polyline. Thus, to draw one segment, three must be specified. To draw two segments, four must be speci-
       fied, etc.

       The normal array may be NULL. If it is, normal vectors will NOT be automatically generated, and the object will look terrible when lit.

       The color array may be NULL. If NULL, the current color is used. If not NULL, the glColor3f() routine is used to set the color;	therefore,
       specifying the glColorMaterial() subroutine before this primitive can be used to set diffuse, specular, ambient, etc. colors.

SEE ALSO

       gleExtrusion, gleSuperExtrusion

AUTHOR

       Linas Vepstas (linas@linas.org)

GLE
									3.0						   gleTwistExtrusion(3GLE)

gle(3GLE)								GLE								 gle(3GLE)

NAME

       gle - an introduction to the GLE Tubing & Extrusions Library

SYNOPSIS

       #include <GL/gle.h>

DESCRIPTION

       The  GLE  Tubing  and Extrusion Library is a graphics application programming interface (API). The library consists of a number of "C" lan-
       guage subroutines for drawing tubing and extrusions. The library is distributed in source code form, in a package that includes	documenta-
       tion,  a  VRML  proposal,  Makefiles,  and full source code and header files. It uses the OpenGL (TM) programming API to perform the actual
       drawing of the tubing and extrusions.

       A "sweep" or "extrusion" is a 2D contour (polyline) that is swept or extruded along a 3D path (polyline). For example,  sweeping  a  circle
       along a straight line will generate a cylinder.	Sweeping a circle along a circular path will generate a doughnut (torus).

       The library also includes a set of utility routines for drawing some of the more common extruded shapes: a polycylinder, a polycone, a gen-
       eralized torus (circle swept along a helical path), a "helix" (arbitrary contour swept along a helical path) and a "lathe" (arbitrary  con-
       tour swept along a helical path, with torsion used to keep the contour aligned).

       The  most general extrusion supported by this library allows an arbitrary 2D contour to be swept around an arbitrary 3D path. A set of nor-
       mal vectors can be specified to go along with the contour; the normal vectors determine the appearance of  the  contour	when  lighting	is
       turned on. A set of colors and affine matrices can be specified to go along with the 3D path.  The colors are used to color along the path.
       The affine matrices are used to operate on the contour as it is swept along. If no affine matrices are specified, the contour  is  extruded
       using  the  mathematical  concept  of "parallel translation" or "Gaussian translation". That is, the contour is moved (and drawn) along the
       extrusion path in a "straight" manner. If there are affine matrices, they are applied to the contour at each extrusion segment  before  the
       segment is drawn.

       The affine matrices allow work in a quasi-non-Euclidean space. They essentially allow the contour to be distorted as it is swept along. The
       allow the contour to be rotated, translated and rescaled as it is drawn. For example, a rescaling will turn a  polycylinder  into  a  poly-
       cone,  since  the circle that is being extruded is scaled to a different size at each extrusion vertex. A rotation allows the contour to be
       spun around while it is being extruded, thus for instance allowing drill-bit type shapes to be drawn. A translation allows  the	appearance
       of  shearing in real space; that is, taking a contour and displacing it, without otherwise bending it. Note that the affines are 2x3 matri-
       ces, not 3x4 matrices, since they apply to the 2D contour as it is being extruded.

WEB SITE

       http://linas.org/gle/index.html

SEE ALSO

       gleExtrusion, gleHelicoid, gleLathe, glePolyCone, glePolyCylinder, gleScrew, gleSetJoinStyle, gleSpiral, gleSuperExtrusion, gleTextureMode,
       gleToroid, gleTwistExtrusion, gleTwistExtrusion, gleSuperExtrusion

AUTHOR

       Linas Vepstas (linas@linas.org)

GLE
									3.0								 gle(3GLE)