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25 //
26 //
27 //
28 //
29 // John Allison 15th July 2012
30 // Model that knows how to draw an arrow.
31
32 #include "G4ArrowModel.hh"
33
34 #include "G4PhysicalConstants.hh"
35 #include "G4VGraphicsScene.hh"
36 #include "G4VisAttributes.hh"
37 #include "G4Tubs.hh"
38 #include "G4Tet.hh"
39 #include "G4Polyhedron.hh"
40 #include "G4Vector3D.hh"
41 #include "G4Point3D.hh"
42 #include "G4Transform3D.hh"
43 #include "G4GeometryTolerance.hh"
44
45 #include <cmath>
46
47 G4ArrowModel::~G4ArrowModel ()
48 {
49 delete fpHeadPolyhedron;
50 delete fpShaftPolyhedron;
51 }
52
53 G4ArrowModel::G4ArrowModel
54 (G4double x1, G4double y1, G4double z1,
55 G4double x2, G4double y2, G4double z2,
56 G4double width, const G4Colour& colour,
57 const G4String& description,
58 G4int lineSegmentsPerCircle,
59 const G4Transform3D& transform)
60 : fpShaftPolyhedron(nullptr)
61 , fpHeadPolyhedron(nullptr)
62 , fTransform(transform)
63 {
64 fType = "G4ArrowModel";
65 fGlobalTag = fType;
66 fGlobalDescription = fType + ": " + description;
67 fExtent = G4VisExtent
68 (std::min(x1,x2),
69 std::max(x1,x2),
70 std::min(y1,y2),
71 std::max(y1,y2),
72 std::min(z1,z2),
73 std::max(z1,z2));
74
75 // Force number of line segments per circle (aka number of rotation steps)
76 G4int tempN = G4Polyhedron::GetNumberOfRotationSteps();
77 G4Polyhedron::SetNumberOfRotationSteps(lineSegmentsPerCircle);
78
79 // Make a cylinder slightly shorter than the arrow length so that it
80 // doesn't stick out of the head.
81 const G4double tolerance = G4GeometryTolerance::GetInstance()->GetRadialTolerance();
82
83 G4double totalLength = std::hypot(x2-x1, y2-y1, z2-z1);
84 if (totalLength < tolerance)
85 {totalLength = tolerance;}
86
87 G4double shaftRadius = width/6.;
88 if (shaftRadius < tolerance)
89 {shaftRadius = tolerance;}
90
91 // case 1 - arrow length >> width -> arrow head is width and 1.5x width tall
92 // case 2 - arrow length < width -> arrow head is made to be 0.5x length
93 G4double arrowLength = std::min(1.5*width, 0.5*totalLength);
94
95 G4double shaftLength = totalLength - arrowLength;
96 if (shaftLength < 2*tolerance)
97 {shaftLength = 2*tolerance;}
98
99 const G4Tubs shaft("shaft",0.,shaftRadius,0.5*shaftLength,0.,twopi);
100 fpShaftPolyhedron = shaft.CreatePolyhedron();
101 // translate the polyhedron down w.r.t. the centre of the whole arrow
102 if (fpShaftPolyhedron)
103 {fpShaftPolyhedron->Transform(G4Translate3D(0,0,-0.5*arrowLength));}
104
105 // Locate the head at +halfShaftLength.
106 const G4double zHi = 0.5*totalLength;
107 const G4double zLow = zHi - arrowLength;
108 const G4double rExt = 0.5*width;
109 const G4double xExt = std::sqrt(3.)*rExt/2.;
110 const G4Tet head("head",
111 G4ThreeVector(0.,0.,zHi),
112 G4ThreeVector(0.,rExt,zLow),
113 G4ThreeVector(xExt,-rExt/2.,zLow),
114 G4ThreeVector(-xExt,-rExt/2.,zLow));
115 fpHeadPolyhedron = head.CreatePolyhedron();
116
117 // Transform to position
118 const G4Vector3D arrowDirection = G4Vector3D(x2-x1,y2-y1,z2-z1).unit();
119 const G4double theta = arrowDirection.theta();
120 const G4double phi = arrowDirection.phi();
121 const G4Point3D arrowCentre(0.5*(x1+x2),0.5*(y1+y2),0.5*(z1+z2));
122 const G4Transform3D tr =
123 G4Translate3D(arrowCentre) * G4RotateZ3D(phi) * G4RotateY3D(theta);
124 if (fpShaftPolyhedron) fpShaftPolyhedron->Transform(tr);
125 if (fpHeadPolyhedron) fpHeadPolyhedron->Transform(tr);
126
127 G4VisAttributes va;
128 va.SetColour(colour);
129 va.SetForceSolid(true);
130 if (fpShaftPolyhedron) fpShaftPolyhedron->SetVisAttributes(va);
131 if (fpHeadPolyhedron) fpHeadPolyhedron->SetVisAttributes(va);
132
133 // Restore number of line segments per circle
134 G4Polyhedron::SetNumberOfRotationSteps(tempN);
135 }
136
137 void G4ArrowModel::DescribeYourselfTo (G4VGraphicsScene& sceneHandler)
138 {
139 if (fpShaftPolyhedron && fpHeadPolyhedron) {
140 sceneHandler.BeginPrimitives(fTransform);
141 sceneHandler.AddPrimitive(*fpShaftPolyhedron);
142 sceneHandler.AddPrimitive(*fpHeadPolyhedron);
143 sceneHandler.EndPrimitives();
144 }
145 }
146