eic-opticks/sysrap/SPlace.h

0001 #pragma once
0002
0003 #include "SPlaceSphere.h"
0004 #include "SPlaceCylinder.h"
0005 #include "SPlaceCircle.h"
0006
0007
0008 struct SPlace
0009 {
0010     static constexpr const char* OPTS = "TR,tr,R,T,r,t" ;
0011     static NP* AroundSphere(   const char* opts, double radius, double item_arclen, unsigned num_ring=10 );
0012     static NP* AroundCylinder( const char* opts, double radius, double halfheight , unsigned num_ring=10, unsigned num_in_ring=16  );
0013     static NP* AroundCircle(   const char* opts, double radius, unsigned numInRing=4, double fracPhase=0. );
0014 };
0015
0016
0017 /**
0018 SPlace::AroundSphere
0019 -----------------------
0020
0021 The number within each ring at a particular z is determined
0022 from the circumference the ring at that z.
0023
0024
0025
0026
0027
0028             +---+
0029         +------------+
0030       +----------------+
0031         +------------+
0032             +---+
0033
0034
0035      x = r sin th cos ph
0036      y = r sin th sin ph       x^2 + y^2 = r^2 sin^2 th
0037      z = r cos th                    z^2 = r^2 cos^2 th
0038
0039     cos th = z/r
0040     sin th = sqrt( 1 - (z/r)^2 )
0041
0042
0043                r sin th
0044          +. .+. .+
0045           \  |  /|
0046            \ | / | r cos th
0047             \|/  |
0048    ---+------+---+---+
0049                  r
0050
0051
0052 Circumference of ring : 2*pi*(r*sin th) = 2*pi*r*sqrt(1 - (z/r)^2 )
0053 at z=0 -> 2*pi*r at z =r  -> 0
0054
0055 **/
0056
0057
0058 NP* SPlace::AroundSphere(const char* opts_, double radius, double item_arclen, unsigned num_ring )
0059 {
0060     const char* opts = opts_ ? opts_ : OPTS ;
0061     SPlaceSphere sp(radius, item_arclen, num_ring);
0062     return sp.transforms(opts)  ;
0063 }
0064
0065
0066 /**
0067 SPlace::AroundCylinder
0068 ------------------------
0069
0070 Form placement transforms that orient local-Z axis to
0071 a radial outwards direction with translation at points around the cylinder.
0072
0073 flip:false(default)
0074     transform memory layout has last 4 of 16 elements (actually 12,13,14)
0075     holding the translation, which corresponds to the OpenGL standard
0076
0077 flip:true
0078     transform memory layout has translation in right hand column at elements 3,7,11
0079     this is needed by pyvista it seems
0080     This corresponds to the transposed transform compared with flip:false
0081
0082 **/
0083
0084 NP* SPlace::AroundCylinder(const char* opts_, double radius, double halfheight, unsigned num_ring, unsigned num_in_ring )
0085 {
0086     const char* opts = opts_ ? opts_ : OPTS ;
0087     SPlaceCylinder cy(radius, halfheight, num_ring, num_in_ring );
0088     return cy.transforms(opts)  ;
0089 }
0090
0091
0092 /**
0093 SPlace::AroundCircle
0094 ---------------------
0095
0096 Circle currently fixed in XZ plane
0097
0098 **/
0099
0100 NP* SPlace::AroundCircle(const char* opts_, double radius, unsigned numInRing, double fracPhase )
0101 {
0102     const char* opts = opts_ ? opts_ : OPTS ;
0103     SPlaceCircle ci(radius, numInRing, fracPhase );
0104     return ci.transforms(opts)  ;
0105 }
0106
0107