nvp2pl_c |
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Procedurenvp2pl_c ( Normal vector and point to plane ) void nvp2pl_c ( ConstSpiceDouble normal[3], ConstSpiceDouble point [3], SpicePlane * plane ) AbstractMake a SPICE plane from a normal vector and a point. Required_ReadingPLANES KeywordsGEOMETRY MATH PLANE Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- normal, point I A normal vector and a point defining a plane. plane O A SPICE plane structure representing the plane. Detailed_Inputnormal, point are, respectively, a normal vector and point that define a plane in three-dimensional space. normal need not be a unit vector. Let the symbol < a, b > indicate the inner product of vectors a and b; then the geometric plane is the set of vectors x in three-dimensional space that satisfy < x - point, normal > = 0. Detailed_Outputplane is a SPICE plane structure that represents the geometric plane defined by point and normal. ParametersNone. Exceptions1) If the input vector `normal' is the zero vector, the error SPICE(ZEROVECTOR) is signaled. FilesNone. ParticularsCSPICE geometry routines that deal with planes use the `plane' data type to represent input and output planes. This data type makes the routine interfaces simpler and more uniform. The CSPICE routines that produce SPICE planes from data that define a plane are: nvc2pl_c ( Normal vector and constant to plane ) nvp2pl_c ( Normal vector and point to plane ) psv2pl_c ( Point and spanning vectors to plane ) The CSPICE routines that convert SPICE planes to data that define a plane are: pl2nvc_c ( Plane to normal vector and constant ) pl2nvp_c ( Plane to normal vector and point ) pl2psv_c ( Plane to point and spanning vectors ) Any of these last three routines may be used to convert this routine's output, `plane', to another representation of a geometric plane. Examples1) Project a vector v orthogonally onto a plane defined by point and normal. proj is the projection we want; it is the closest vector in the plane to v. nvp2pl_c ( normal, point, &plane ); vprjp_c ( v, &plane, proj ); 2) Given a point in a plane and a normal vector, find the distance of the plane from the origin. We make a `plane' from the point and normal, then convert the plane to a unit normal and constant. The output constant is (according to the specification of pl2nvc_c) the distance of the plane from the origin. nvp2pl_c ( normal, point, &plane ); pl2nvc_c ( &plane, normal, constant ); RestrictionsNone. Literature_References[1] G. Thomas and R. Finney, "Calculus and Analytic Geometry," 7th Edition, Addison Wesley, 1988. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) Version-CSPICE Version 1.0.1, 24-AUG-2021 (JDR) Edited the header to comply with NAIF standard. -CSPICE Version 1.0.0, 05-MAR-1999 (NJB) Index_Entriesnormal vector and point to plane |
Fri Dec 31 18:41:10 2021