+++ /dev/null
-/**************************************************************************
- * Copyright(c) 2004, ALICE Experiment at CERN, All rights reserved. *
- * *
- * Author: The ALICE Off-line Project. *
- * Contributors are mentioned in the code where appropriate. *
- * *
- * Permission to use, copy, modify and distribute this software and its *
- * documentation strictly for non-commercial purposes is hereby granted *
- * without fee, provided that the above copyright notice appears in all *
- * copies and that both the copyright notice and this permission notice *
- * appear in the supporting documentation. The authors make no claims *
- * about the suitability of this software for any purpose. It is *
- * provided "as is" without express or implied warranty. *
- **************************************************************************/
-
-/* $Id$ */
-
-//////////////////////////////////////////////////////////////////////////////
-//
-// Utility class to help implement shape of the FMD modules
-//
-// Latest changes by Christian Holm Christensen
-//
-//////////////////////////////////////////////////////////////////////////////
-#include "AliFMDPolygon.h" // ALIFMDPOLYGON_H
-#include "AliLog.h" // ALILOG_H
-#include "TString.h" // ROOT_TString
-#include "TVector2.h" // ROOT_TVector2
-#include "TCanvas.h" // ROOT_TCanvas
-#include "TText.h" // ROOT_TText
-#include "TGraph.h" // ROOT_TGraph
-#include "TError.h" // ROOT_TError
-
-//____________________________________________________________________
-ClassImp(AliFMDPolygon)
-
-//____________________________________________________________________
-AliFMDPolygon::AliFMDPolygon()
- : fState(kUnknown)
-{}
-
-//____________________________________________________________________
-AliFMDPolygon::~AliFMDPolygon()
-{
- fVerticies.Delete();
-}
-
-//____________________________________________________________________
-bool
-AliFMDPolygon::AddVertex(double x, double y)
-{
- // Add points in order to the polygon.
- TVector2* c = new TVector2(x,y);
- return AddVertex(c);
-}
-//____________________________________________________________________
-bool
-AliFMDPolygon::AddVertex(TVector2* c)
-{
- // Add points in order to the polygon.
- //
- // Checks if the addition of the vertex makes the alipolygon
- // concave, and if it does, returns false. Note, that the check
- // isn't performed until at least 3 verticies have already been
- // added to the alipolygon (a triangle is always convex).
- if (!c) return false;
- if (fVerticies.GetEntries() >= 3) {
- if (!IsOnLeftHand(c, fVerticies.GetEntries()-2,
- fVerticies.GetEntries()-1)) {
- Error("AliFMDPolygon::AddVertex",
- "Adding vertex (%f,%f) makes alipolygon concave",
- c->X(), c->Y());
- return false;
- }
- }
- fState = kUnknown;
- fVerticies.AddAtAndExpand(c, fVerticies.GetEntries());
- return true;
-}
-
-//____________________________________________________________________
-const TVector2&
-AliFMDPolygon::GetVertex(size_t i) const
-{
- // Get one of the verticies
- if (i > size_t(fVerticies.GetEntries()))
- Fatal("AliFMDPolygon::GetVertex", "Index %d out of range [0,%d]",
- i, fVerticies.GetEntries());
- return *(static_cast<TVector2*>(fVerticies.At(i)));
-}
-
-//____________________________________________________________________
-bool
-AliFMDPolygon::Contains(const TVector2* c) const
-{
- /* This function checks if a point is inside the polygon. It does
- * that by looping over the segments of the polygon, and decides
- * wether the point is on the left-hand-side (LHS) of the segment.
- *
- * Suppose we had the polygon and point
- *
- * 2 x----x 1
- * / \\
- * 3 x P x 0
- * \\ /
- * 4 x----x 5
- *
- * Then, P is on LHS of the segment 0->1, 1->2, ..., and 5->0, and
- * so inside the polygon.
- *
- * Suppose instead the point was like
- *
- * 2 x----x 1
- * / \\ P
- * 3 x x 0
- * \\ /
- * 4 x----x 5
- *
- * Then it would still be on the LHS of the segments 1->2, 2->3,
- * 3->4, 4->5, but on the right-hand-side of 5->0, and 0->1 and
- * hence outside the polygon.
- */
- if (!c) return kFALSE;
- if (fState == kUnknown) fState = (ConvexCheck() ? kConvex : kConcave);
- if (fState == kConcave) return false;
- size_t n = fVerticies.GetEntries();
- for (size_t i = 0; i < n; ++i)
- if (!IsOnLeftHand(c, i, (i + 1) % n))
- // If point is on the left hand side of the segment, it's
- // outside the polygon.
- return false;
- return true;
-}
-
-//____________________________________________________________________
-bool
-AliFMDPolygon::Contains(double x, double y) const
-{
- TVector2 c(x,y);
- return Contains(&c);
-}
-
-//____________________________________________________________________
-bool
-AliFMDPolygon::ConvexCheck() const
-{
- /*
- * This member function loops through the verticies, and checks if
- * the next-to-next vertex is in between the current vertex and the
- * next vertex.
- *
- * Suppose we have the polygon
- *
- * 2 x----x 1
- * / \\
- * 3 x x 0
- * \\ /
- * 4 x----x 5
- *
- * Then the vertex 2 is on the left-hand-side (LHS) of the segment
- * 0->1, 3 is on the LHS of 1->2, ..., and 0 is on the RHS of 4->5,
- * and so the polygon is convex.
- *
- * If we had a polygon like
- *
- * 2 x----x 1
- * \\ \\
- * 3 x x 0
- * / /
- * 4 x----x 5
- *
- * Then, the vertex 4 is NOT on the LHS of the segment 2->3, and so
- * the polygon is NOT convex.
- */
- size_t n = fVerticies.GetEntries();
- // A triangle is always convex.
- if (n <= 3) return true;
- for (size_t i = 0; i < n; i++) {
- // Get the next, and next-to-next indicies, taking care to go
- // around the polygon.
- size_t j = (i + 1) % n;
- size_t k = (i + 2) % n;
- // Check The next-to-next vertex is on the LHS of the current
- // vertex and the next vertex
- if (!IsOnLeftHand(static_cast<TVector2*>(fVerticies.At(k)), i, j)) {
- Error("AliFMDPolygon::ConvexCheck",
- "AliFMDPolygon is concave at segment %d -> %d" , i, j);
- return false;
- }
- }
- return true;
-}
-
-//____________________________________________________________________
-bool
-AliFMDPolygon::IsOnLeftHand(const TVector2* c, size_t i1, size_t i2) const
-{
- /* Check if a point is on the left-hand-side (LHS) or
- * right-hand-side (RHS) of the segment defined by the two indicies.
- *
- * Suppose we have the segment and point
- *
- * 1 x
- * \\ P
- * x 0
- *
- * Then, we define the vectors
- *
- * v: 0->P
- * u: perpendicular to 1->0
- *
- * The dot product of u and v is >= 0, meaning that the
- * angle between the two vectors is in [0,pi], and so P is on the
- * RHS of the segment
- *
- * Suppose we had
- *
- * 1 x
- * P \\
- * x 0
- *
- * And defining the vectors u,v as above. In this case the dot
- * product is less than 0, meaning the angle between u,v is in
- * (pi,2pi], and so P is on the LHS of the segment
- */
- if (!c) return false;
- const TVector2& v1 = GetVertex(i1);
- const TVector2& v2 = GetVertex(i2);
- double dot = ( (c->X() - v1.X()) * (v2.Y() - v1.Y())
- - (c->Y() - v1.Y()) * (v2.X() - v1.X()));
- return (dot < 0 ? true : false);
-}
-
-//____________________________________________________________________
-void
-AliFMDPolygon::Clear(Option_t*)
-{
- fState = kUnknown;
- fVerticies.Delete();
- // fVerticies.Resize(0);
-}
-
-//____________________________________________________________________
-void
-AliFMDPolygon::Draw(const char* option, const char* name) const
-{
- size_t n = fVerticies.GetEntries();
- TGraph* g = new TGraph(n+1);
- if (name) g->SetName(name);
- g->SetMarkerStyle(20);
- for (size_t i = 0; i < n; i++) {
- const TVector2& v = GetVertex(i);
- g->SetPoint(i, v.X(), v.Y());
- }
- const TVector2& v = GetVertex(0);
- g->SetPoint(n, v.X(), v.Y());
- g->Draw(option);
- TString opt(option);
- if (!opt.Contains("p", TString::kIgnoreCase))
- return;
- for (size_t i = 0; i < n; i++) {
- const TVector2& v = GetVertex(i);
- TText* t = new TText(v.X(), v.Y(), Form("%d", i));
- t->Draw();
- }
-}
-
-//____________________________________________________________________
-//
-// EOf
-//
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff