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edc97986 | 1 | /************************************************************************** |
2 | * Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
7 | * Permission to use, copy, modify and distribute this software and its * | |
8 | * documentation strictly for non-commercial purposes is hereby granted * | |
9 | * without fee, provided that the above copyright notice appears in all * | |
10 | * copies and that both the copyright notice and this permission notice * | |
11 | * appear in the supporting documentation. The authors make no claims * | |
12 | * about the suitability of this software for any purpose. It is * | |
13 | * provided "as is" without express or implied warranty. * | |
14 | **************************************************************************/ | |
15 | /////////////////////////////////////////////////////////////////// | |
16 | // // | |
17 | // A straight line is coded as a point (3 Double_t) and // | |
18 | // 3 direction cosines // | |
19 | // // | |
20 | /////////////////////////////////////////////////////////////////// | |
21 | #include <Riostream.h> | |
22 | #include <TTree.h> | |
23 | #include "AliStrLine.h" | |
24 | ||
25 | ClassImp(AliStrLine) | |
26 | ||
27 | //________________________________________________________ | |
fe12e09c | 28 | AliStrLine::AliStrLine() : |
29 | TObject(), | |
30 | fTpar(0), | |
31 | fDebug(0) | |
32 | { | |
edc97986 | 33 | // Default constructor |
34 | for(Int_t i=0;i<3;i++) { | |
35 | fP0[i] = 0.; | |
36 | fCd[i] = 0.; | |
37 | } | |
edc97986 | 38 | } |
39 | ||
40 | //________________________________________________________ | |
fe12e09c | 41 | AliStrLine::AliStrLine(Double_t *point, Double_t *cd,Bool_t twopoints) : |
42 | TObject(), | |
43 | fTpar(0), | |
44 | fDebug(0) | |
45 | { | |
edc97986 | 46 | // Standard constructor |
24a0c65f | 47 | // if twopoints is true: point and cd are the 3D coordinates of |
48 | // two points defininig the straight line | |
49 | // if twopoint is false: point represents the 3D coordinates of a point | |
50 | // belonging to the straight line and cd is the | |
51 | // direction in space | |
52 | if(twopoints){ | |
53 | InitTwoPoints(point,cd); | |
54 | } | |
55 | else { | |
56 | InitDirection(point,cd); | |
57 | } | |
58 | } | |
59 | ||
60 | ||
61 | //________________________________________________________ | |
62 | void AliStrLine::InitDirection(Double_t *point, Double_t *cd){ | |
63 | // Initialization from a point and a direction | |
edc97986 | 64 | Double_t norm = 0.; |
65 | for(Int_t i=0;i<3;i++)norm+=cd[i]*cd[i]; | |
66 | if(norm) { | |
67 | norm = TMath::Sqrt(norm); | |
68 | for(Int_t i=0;i<3;i++) cd[i]/=norm; | |
69 | } | |
70 | else { | |
71 | Error("AliStrLine","Null direction cosines!!!"); | |
72 | } | |
73 | SetP0(point); | |
74 | SetCd(cd); | |
75 | fTpar = 0.; | |
76 | SetDebug(); | |
77 | } | |
78 | ||
24a0c65f | 79 | //________________________________________________________ |
80 | void AliStrLine::InitTwoPoints(Double_t *pA, Double_t *pB){ | |
81 | // Initialization from the coordinates of two | |
82 | // points in the space | |
83 | Double_t cd[3]; | |
84 | for(Int_t i=0;i<3;i++)cd[i] = pB[i]-pA[i]; | |
85 | InitDirection(pA,cd); | |
86 | } | |
87 | ||
edc97986 | 88 | //________________________________________________________ |
89 | AliStrLine::~AliStrLine() { | |
90 | // destructor | |
91 | } | |
92 | ||
93 | //________________________________________________________ | |
94 | void AliStrLine::PrintStatus() const { | |
95 | // Print current status | |
96 | cout <<"=======================================================\n"; | |
97 | cout <<"Direction cosines: "; | |
98 | for(Int_t i=0;i<3;i++)cout <<fCd[i]<<"; "; | |
99 | cout <<endl; | |
100 | cout <<"Known point: "; | |
101 | for(Int_t i=0;i<3;i++)cout <<fP0[i]<<"; "; | |
102 | cout <<endl; | |
103 | cout <<"Current value for the parameter: "<<fTpar<<endl; | |
104 | cout <<" Debug flag: "<<fDebug<<endl; | |
105 | } | |
106 | ||
107 | //________________________________________________________ | |
108 | Int_t AliStrLine::IsParallelTo(AliStrLine *line) const { | |
109 | // returns 1 if lines are parallel, 0 if not paralel | |
110 | Double_t cd2[3]; | |
111 | line->GetCd(cd2); | |
112 | Double_t vecpx=fCd[1]*cd2[2]-fCd[2]*cd2[1]; | |
113 | if(vecpx!=0) return 0; | |
114 | Double_t vecpy=-fCd[0]*cd2[2]+fCd[2]*cd2[0]; | |
115 | if(vecpy!=0) return 0; | |
116 | Double_t vecpz=fCd[0]*cd2[1]-fCd[1]*cd2[0]; | |
117 | if(vecpz!=0) return 0; | |
118 | return 1; | |
119 | } | |
120 | //________________________________________________________ | |
121 | Int_t AliStrLine::Crossrphi(AliStrLine *line){ | |
122 | // Cross 2 lines in the X-Y plane | |
123 | Double_t p2[3]; | |
124 | Double_t cd2[3]; | |
125 | line->GetP0(p2); | |
126 | line->GetCd(cd2); | |
127 | Double_t a=fCd[0]; | |
128 | Double_t b=-cd2[0]; | |
129 | Double_t c=p2[0]-fP0[0]; | |
130 | Double_t d=fCd[1]; | |
131 | Double_t e=-cd2[1]; | |
132 | Double_t f=p2[1]-fP0[1]; | |
133 | Double_t deno = a*e-b*d; | |
134 | Int_t retcode = 0; | |
135 | if(deno != 0.) { | |
136 | fTpar = (c*e-b*f)/deno; | |
137 | } | |
138 | else { | |
139 | retcode = -1; | |
140 | } | |
141 | return retcode; | |
142 | } | |
143 | ||
144 | //________________________________________________________ | |
145 | Int_t AliStrLine::CrossPoints(AliStrLine *line, Double_t *point1, Double_t *point2){ | |
146 | // Looks for the crossing point estimated starting from the | |
147 | // DCA segment | |
148 | Double_t p2[3]; | |
149 | Double_t cd2[3]; | |
150 | line->GetP0(p2); | |
151 | line->GetCd(cd2); | |
152 | Int_t i; | |
153 | Double_t k1 = 0; | |
154 | for(i=0;i<3;i++)k1+=(fP0[i]-p2[i])*fCd[i]; | |
155 | Double_t k2 = 0; | |
156 | for(i=0;i<3;i++)k2+=(fP0[i]-p2[i])*cd2[i]; | |
157 | Double_t a11 = 0; | |
158 | for(i=0;i<3;i++)a11+=fCd[i]*cd2[i]; | |
159 | Double_t a22 = -a11; | |
160 | Double_t a21 = 0; | |
161 | for(i=0;i<3;i++)a21+=cd2[i]*cd2[i]; | |
162 | Double_t a12 = 0; | |
163 | for(i=0;i<3;i++)a12-=fCd[i]*fCd[i]; | |
164 | Double_t deno = a11*a22-a21*a12; | |
165 | if(deno == 0.) return -1; | |
166 | fTpar = (a11*k2-a21*k1) / deno; | |
167 | Double_t par2 = (k1*a22-k2*a12) / deno; | |
168 | line->SetPar(par2); | |
169 | GetCurrentPoint(point1); | |
170 | line->GetCurrentPoint(point2); | |
171 | return 0; | |
172 | } | |
173 | //________________________________________________________________ | |
174 | Int_t AliStrLine::Cross(AliStrLine *line, Double_t *point){ | |
175 | ||
176 | //Finds intersection between lines | |
177 | Double_t point1[3]; | |
178 | Double_t point2[3]; | |
179 | Int_t retcod=CrossPoints(line,point1,point2); | |
180 | if(retcod==0){ | |
181 | for(Int_t i=0;i<3;i++)point[i]=(point1[i]+point2[i])/2.; | |
182 | return 0; | |
183 | }else{ | |
184 | return -1; | |
185 | } | |
186 | } | |
187 | ||
188 | //___________________________________________________________ | |
189 | Double_t AliStrLine::GetDCA(AliStrLine *line){ | |
190 | //Returns the distance of closest approach between two lines | |
191 | Double_t p2[3]; | |
192 | Double_t cd2[3]; | |
193 | line->GetP0(p2); | |
194 | line->GetCd(cd2); | |
195 | Int_t i; | |
196 | Int_t ispar=IsParallelTo(line); | |
197 | if(ispar){ | |
198 | Double_t dist1q=0,dist2=0,mod=0; | |
199 | for(i=0;i<3;i++){ | |
200 | dist1q+=(fP0[i]-p2[i])*(fP0[i]-p2[i]); | |
201 | dist2+=(fP0[i]-p2[i])*fCd[i]; | |
202 | mod+=fCd[i]*fCd[i]; | |
203 | } | |
204 | if(mod!=0){ | |
205 | dist2/=mod; | |
206 | return TMath::Sqrt(dist1q-dist2*dist2); | |
207 | }else{return -1;} | |
208 | }else{ | |
209 | Double_t perp[3]; | |
210 | perp[0]=fCd[1]*cd2[2]-fCd[2]*cd2[1]; | |
211 | perp[1]=-fCd[0]*cd2[2]+fCd[2]*cd2[0]; | |
212 | perp[2]=fCd[0]*cd2[1]-fCd[1]*cd2[0]; | |
213 | Double_t mod=0,dist=0; | |
214 | for(i=0;i<3;i++){ | |
215 | mod+=perp[i]*perp[i]; | |
216 | dist+=(fP0[i]-p2[i])*perp[i]; | |
217 | } | |
218 | mod=sqrt(mod); | |
219 | if(mod!=0){ | |
220 | dist/=mod; | |
221 | return TMath::Abs(dist); | |
222 | }else{return -1;} | |
223 | } | |
224 | } | |
225 | //________________________________________________________ | |
226 | void AliStrLine::GetCurrentPoint(Double_t *point) const { | |
227 | // Fills the array point with the current value on the line | |
228 | for(Int_t i=0;i<3;i++)point[i]=fP0[i]+fCd[i]*fTpar; | |
229 | } |