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geant4/source/geometry/solids/specific/src/G4ReduciblePolygon.cc
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2016-06-09 15:58:43 +02:00

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//
// ********************************************************************
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// * *
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// * technical work of the GEANT4 collaboration. *
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//
//
// $Id: G4ReduciblePolygon.cc,v 1.11 2006/06/29 18:48:53 gunter Exp $
// GEANT4 tag $Name: geant4-09-02 $
//
//
// --------------------------------------------------------------------
// GEANT 4 class source file
//
//
// G4ReduciblePolygon.cc
//
// Implementation of a utility class used to specify, test, reduce,
// and/or otherwise manipulate a 2D polygon.
//
// See G4ReduciblePolygon.hh for more info.
//
// --------------------------------------------------------------------
#include "G4ReduciblePolygon.hh"
#include "globals.hh"
//
// Constructor: with simple arrays
//
G4ReduciblePolygon::G4ReduciblePolygon( const G4double a[],
const G4double b[],
G4int n )
: aMin(0.), aMax(0.), bMin(0.), bMax(0.),
vertexHead(0)
{
//
// Do all of the real work in Create
//
Create( a, b, n );
}
//
// Constructor: special PGON/PCON case
//
G4ReduciblePolygon::G4ReduciblePolygon( const G4double rmin[],
const G4double rmax[],
const G4double z[], G4int n )
: aMin(0.), aMax(0.), bMin(0.), bMax(0.),
vertexHead(0)
{
//
// Translate
//
G4double *a = new G4double[n*2];
G4double *b = new G4double[n*2];
G4double *rOut = a + n,
*zOut = b + n,
*rIn = rOut-1,
*zIn = zOut-1;
G4int i;
for( i=0; i < n; i++, rOut++, zOut++, rIn--, zIn-- )
{
*rOut = rmax[i];
*rIn = rmin[i];
*zOut = *zIn = z[i];
}
Create( a, b, n*2 );
delete [] a;
delete [] b;
}
//
// Create
//
// To be called by constructors, fill in the list and statistics for a new
// polygon
//
void G4ReduciblePolygon::Create( const G4double a[],
const G4double b[], G4int n )
{
if (n<3)
G4Exception("G4ReduciblePolygon::Create()", "WrongArgumentValue",
FatalException, "Less than 3 vertices specified.");
const G4double *anext = a, *bnext = b;
ABVertex *prev = 0;
do
{
ABVertex *newVertex = new ABVertex;
newVertex->a = *anext;
newVertex->b = *bnext;
newVertex->next = 0;
if (prev==0)
{
vertexHead = newVertex;
}
else
{
prev->next = newVertex;
}
prev = newVertex;
} while( ++anext, ++bnext < b+n );
numVertices = n;
CalculateMaxMin();
}
//
// Fake default constructor - sets only member data and allocates memory
// for usage restricted to object persistency.
//
G4ReduciblePolygon::G4ReduciblePolygon( __void__& )
: aMin(0.), aMax(0.), bMin(0.), bMax(0.), vertexHead(0)
{
}
//
// Destructor
//
G4ReduciblePolygon::~G4ReduciblePolygon()
{
ABVertex *curr = vertexHead;
while( curr )
{
ABVertex *toDelete = curr;
curr = curr->next;
delete toDelete;
}
}
//
// CopyVertices
//
// Copy contents into simple linear arrays.
// ***** CAUTION ***** Be care to declare the arrays to a large
// enough size!
//
void G4ReduciblePolygon::CopyVertices( G4double a[], G4double b[] ) const
{
G4double *anext = a, *bnext = b;
ABVertex *curr = vertexHead;
while( curr )
{
*anext++ = curr->a;
*bnext++ = curr->b;
curr = curr->next;
}
}
//
// ScaleA
//
// Multiply all a values by a common scale
//
void G4ReduciblePolygon::ScaleA( G4double scale )
{
ABVertex *curr = vertexHead;
while( curr )
{
curr->a *= scale;
curr = curr->next;
}
}
//
// ScaleB
//
// Multiply all b values by a common scale
//
void G4ReduciblePolygon::ScaleB( G4double scale )
{
ABVertex *curr = vertexHead;
while( curr )
{
curr->b *= scale;
curr = curr->next;
}
}
//
// RemoveDuplicateVertices
//
// Remove adjacent vertices that are equal. Returns "false" if there
// is a problem (too few vertices remaining).
//
G4bool G4ReduciblePolygon::RemoveDuplicateVertices( G4double tolerance )
{
ABVertex *curr = vertexHead,
*prev = 0,
*next = curr->next; // A little dangerous
while( curr )
{
next = curr->next;
if (next == 0) next = vertexHead;
if (std::fabs(curr->a-next->a) < tolerance &&
std::fabs(curr->b-next->b) < tolerance )
{
//
// Duplicate found: do we have > 3 vertices?
//
if (numVertices <= 3)
{
CalculateMaxMin();
return false;
}
//
// Delete
//
ABVertex *toDelete = curr;
curr = curr->next;
delete toDelete;
numVertices--;
if (prev) prev->next = curr; else vertexHead = curr;
}
else
{
prev = curr;
curr = curr->next;
}
}
//
// In principle, this is not needed, but why not just play it safe?
//
CalculateMaxMin();
return true;
}
//
// RemoveRedundantVertices
//
// Remove any unneeded vertices, i.e. those vertices which
// are on the line connecting the previous and next vertices.
//
G4bool G4ReduciblePolygon::RemoveRedundantVertices( G4double tolerance )
{
//
// Under these circumstances, we can quit now!
//
if (numVertices <= 2) return false;
G4double tolerance2 = tolerance*tolerance;
//
// Loop over all vertices
//
ABVertex *curr = vertexHead,
*next = curr->next; // A little dangerous
while( curr )
{
next = curr->next;
if (next == 0) next = vertexHead;
G4double da = next->a - curr->a,
db = next->b - curr->b;
//
// Loop over all subsequent vertices, up to curr
//
for(;;)
{
//
// Get vertex after next
//
ABVertex *test = next->next;
if (test == 0) test = vertexHead;
//
// If we are back to the original vertex, stop
//
if (test==curr) break;
//
// Test for parallel line segments
//
G4double dat = test->a - curr->a,
dbt = test->b - curr->b;
if (std::fabs(dat*db-dbt*da)>tolerance2) break;
//
// Redundant vertex found: do we have > 3 vertices?
//
if (numVertices <= 3)
{
CalculateMaxMin();
return false;
}
//
// Delete vertex pointed to by next. Carefully!
//
if (curr->next)
{ // next is not head
if (next->next)
curr->next = test; // next is not tail
else
curr->next = 0; // New tail
}
else
vertexHead = test; // New head
delete next;
numVertices--;
//
// Replace next by the vertex we just tested,
// and keep on going...
//
next = test;
da = dat; db = dbt;
}
curr = curr->next;
}
//
// In principle, this is not needed, but why not just play it safe?
//
CalculateMaxMin();
return true;
}
//
// ReverseOrder
//
// Reverse the order of the vertices
//
void G4ReduciblePolygon::ReverseOrder()
{
//
// Loop over all vertices
//
ABVertex *prev = vertexHead;
if (prev==0) return; // No vertices
ABVertex *curr = prev->next;
if (curr==0) return; // Just one vertex
//
// Our new tail
//
vertexHead->next = 0;
for(;;)
{
//
// Save pointer to next vertex (in original order)
//
ABVertex *save = curr->next;
//
// Replace it with a pointer to the previous one
// (in original order)
//
curr->next = prev;
//
// Last vertex?
//
if (save == 0) break;
//
// Next vertex
//
prev = curr;
curr = save;
}
//
// Our new head
//
vertexHead = curr;
}
//
// CrossesItself
//
// Return "true" if the polygon crosses itself
//
// Warning: this routine is not very fast (runs as N**2)
//
G4bool G4ReduciblePolygon::CrossesItself( G4double tolerance )
{
G4double tolerance2 = tolerance*tolerance;
G4double one = 1.0-tolerance,
zero = tolerance;
//
// Top loop over line segments. By the time we finish
// with the second to last segment, we're done.
//
ABVertex *curr1 = vertexHead, *next1=0;
while (curr1->next) {
next1 = curr1->next;
G4double da1 = next1->a-curr1->a,
db1 = next1->b-curr1->b;
//
// Inner loop over subsequent line segments
//
ABVertex *curr2 = next1->next;
while( curr2 ) {
ABVertex *next2 = curr2->next;
if (next2==0) next2 = vertexHead;
G4double da2 = next2->a-curr2->a,
db2 = next2->b-curr2->b;
G4double a12 = curr2->a-curr1->a,
b12 = curr2->b-curr1->b;
//
// Calculate intersection of the two lines
//
G4double deter = da1*db2 - db1*da2;
if (std::fabs(deter) > tolerance2) {
G4double s1, s2;
s1 = (a12*db2-b12*da2)/deter;
if (s1 >= zero && s1 < one) {
s2 = -(da1*b12-db1*a12)/deter;
if (s2 >= zero && s2 < one) return true;
}
}
curr2 = curr2->next;
}
curr1 = next1;
}
return false;
}
//
// BisectedBy
//
// Decide if a line through two points crosses the polygon, within tolerance
//
G4bool G4ReduciblePolygon::BisectedBy( G4double a1, G4double b1,
G4double a2, G4double b2,
G4double tolerance )
{
G4int nNeg = 0, nPos = 0;
G4double a12 = a2-a1, b12 = b2-b1;
G4double len12 = std::sqrt( a12*a12 + b12*b12 );
a12 /= len12; b12 /= len12;
ABVertex *curr = vertexHead;
do
{
G4double av = curr->a - a1,
bv = curr->b - b1;
G4double cross = av*b12 - bv*a12;
if (cross < -tolerance)
{
if (nPos) return true;
nNeg++;
}
else if (cross > tolerance)
{
if (nNeg) return true;
nPos++;
}
curr = curr->next;
} while( curr );
return false;
}
//
// Area
//
// Calculated signed polygon area, where polygons specified in a
// clockwise manner (where x==a, y==b) have negative area
//
// References: [O' Rourke (C)] pp. 18-27; [Gems II] pp. 5-6:
// "The Area of a Simple Polygon", Jon Rokne.
//
G4double G4ReduciblePolygon::Area()
{
G4double answer = 0;
ABVertex *curr = vertexHead, *next;
do
{
next = curr->next;
if (next==0) next = vertexHead;
answer += curr->a*next->b - curr->b*next->a;
curr = curr->next;
} while( curr );
return 0.5*answer;
}
//
// Print
//
void G4ReduciblePolygon::Print()
{
ABVertex *curr = vertexHead;
do
{
G4cerr << curr->a << " " << curr->b << G4endl;
curr = curr->next;
} while( curr );
}
//
// CalculateMaxMin
//
// To be called when the vertices are changed, this
// routine re-calculates global values
//
void G4ReduciblePolygon::CalculateMaxMin()
{
ABVertex *curr = vertexHead;
aMin = aMax = curr->a;
bMin = bMax = curr->b;
curr = curr->next;
while( curr )
{
if (curr->a < aMin)
aMin = curr->a;
else if (curr->a > aMax)
aMax = curr->a;
if (curr->b < bMin)
bMin = curr->b;
else if (curr->b > bMax)
bMax = curr->b;
curr = curr->next;
}
}