glupartialdisk(3g) [redhat man page]

GLUPARTIALDISK(3G)														GLUPARTIALDISK(3G)

NAME

       gluPartialDisk - draw an arc of a disk

C SPECIFICATION

       void gluPartialDisk( GLUquadric* quad,
			    GLdouble inner,
			    GLdouble outer,
			    GLint slices,
			    GLint loops,
			    GLdouble start,
			    GLdouble sweep )

PARAMETERS

       quad    Specifies a quadrics object (created with gluNewQuadric).

       inner   Specifies the inner radius of the partial disk (can be 0).

       outer   Specifies the outer radius of the partial disk.

       slices  Specifies the number of subdivisions around the z axis.

       loops   Specifies the number of concentric rings about the origin into which the partial disk is subdivided.

       start   Specifies the starting angle, in degrees, of the disk portion.

       sweep   Specifies the sweep angle, in degrees, of the disk portion.

DESCRIPTION

       gluPartialDisk  renders	a partial disk on the z=0 plane. A partial disk is similar to a full disk, except that only the subset of the disk
       from start through start + sweep is included (where 0 degrees is along the +yaxis, 90 degrees along the +x axis, 180 degrees along  the	-y
       axis, and 270 degrees along the -x axis).

       The partial disk has a radius of outer, and contains a concentric circular hole with a radius of inner. If inner is 0, then no hole is gen-
       erated. The partial disk is subdivided around the z axis into slices (like pizza slices), and also about the z axis into rings  (as  speci-
       fied by slices and loops, respectively).

       With  respect  to orientation, the +z side of the partial disk is considered to be outside (see gluQuadricOrientation).	This means that if
       the orientation is set to GLU_OUTSIDE, then any normals generated point along the +z axis. Otherwise, they point along the -z axis.

       If texturing is turned on (with gluQuadricTexture), texture coordinates are generated linearly such that where r=outer, the value at (r, 0,
       0) is (1.0, 0.5), at (0, r, 0) it is (0.5, 1.0), at (-r, 0, 0) it is (0.0, 0.5), and at (0, -r, 0) it is (0.5, 0.0).

SEE ALSO

       gluCylinder(3G), gluDisk(3G), gluNewQuadric(3G), gluQuadricOrientation(3G), gluQuadricTexture(3G), gluSphere(3G)

																GLUPARTIALDISK(3G)

gleSpiral(3GLE) 							GLE							   gleSpiral(3GLE)

NAME

       gleSpiral - Sweep an arbitrary contour along a helical path.

SYNTAX

       void gleSpiral (int ncp,
		       gleDouble contour[][2],
		       gleDouble cont_normal[][2],
		       gleDouble up[3],
		       gleDouble startRadius,	  /* spiral starts in x-y plane */
		       gleDouble drdTheta,	  /* change in radius per revolution */
		       gleDouble startZ,	  /* starting z value */
		       gleDouble dzdTheta,	  /* change in Z per revolution */
		       gleDouble startXform[2][3], /* starting contour affine xform */
		       gleDouble dXformdTheta[2][3], /* tangent change xform per revoln */
		       gleDouble startTheta,	  /* start angle in x-y plane */
		       gleDouble sweepTheta);	  /* degrees to spiral around */

ARGUMENTS

       ncp	 number of contour points

       contour	 2D contour

       cont_normal
		 2D contour normals

       up	 up vector for contour

       startRadius
		 spiral starts in x-y plane

       drdTheta  change in radius per revolution

       startZ	 starting z value

       dzdTheta  change in Z per revolution

       startXform
		 starting contour affine transformation

       dXformdTheta
		 tangent change xform per revolution

       startTheta
		 start angle in x-y plane

       sweepTheta
		 degrees to spiral around

DESCRIPTION

       Sweep an arbitrary contour along a helical path.

       The axis of the helix lies along the modeling coordinate z-axis.

       An affine transform can be applied as the contour is swept. For most ordinary usage, the affines should be given as NULL.

       The "startXform[][]" is an affine matrix applied to the contour to deform the contour. Thus, "startXform" of the form

	    |  cos     sin    0   |
	    |  -sin    cos    0   |

       will rotate the contour (in the plane of the contour), while

	    |  1    0	 tx   |
	    |  0    1	 ty   |

       will translate the contour, and

	    |  sx    0	  0   |
	    |  0    sy	  0   |

       scales along the two axes of the contour. In particular, note that

	    |  1    0	 0   |
	    |  0    1	 0   |

       is the identity matrix.

       The  "dXformdTheta[][]"	is  a  differential  affine matrix that is integrated while the contour is extruded.  Note that this affine matrix
       lives in the tangent space, and so it should have the form of a generator.  Thus, dx/dt's of the form

	    |  0     r	  0   |
	    |  -r    0	  0   |

       rotate the the contour as it is extruded (r == 0 implies no rotation, r == 2*PI implies that the contour is rotated once, etc.), while

	    |  0    0	 tx   |
	    |  0    0	 ty   |

       translates the contour, and

	    |  sx    0	  0   |
	    |  0    sy	  0   |

       scales it. In particular, note that

	    |  0    0	 0   |
	    |  0    0	 0   |

       is the identity matrix -- i.e. the derivatives are zero, and therefore the integral is a constant.

SEE ALSO

       gleLathe

AUTHOR

       Linas Vepstas (linas@linas.org)

GLE
									3.0							   gleSpiral(3GLE)