[1208] | 1 | <HTML> |
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| 2 | <TITLE>Polylines, Markers and Text</title> |
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| 17 | </TD> |
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| 18 | |
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| 19 | <TD ALIGN="Right"><FONT COLOR="#238E23"><FONT SIZE=-1> |
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| 20 | <B>Geant4 User's Guide</B> <BR> |
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| 21 | <B>For Application Developers</B> <BR> |
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| 22 | <B>Visualization</B> </FONT></FONT> </TD> |
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| 23 | </TR> |
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| 24 | </TABLE> |
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| 25 | |
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| 26 | <CENTER><FONT COLOR="#238E23"><FONT SIZE=+3> |
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| 27 | <b>8.9 Polylines, Markers and Text</b><BR> |
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| 28 | </FONT></FONT></CENTER> |
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| 29 | <BR> |
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| 30 | |
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| 31 | <HR ALIGN="Center" SIZE="7%"><BR> |
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| 32 | |
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| 33 | <!-- ============================================== Section --> |
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| 34 | |
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| 35 | Polylines, markers and text are defined in the <tt>graphics_reps</tt> category, |
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| 36 | and are used only for visualization. Here we explain their definitions and usages. |
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| 37 | |
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| 38 | <h4>8.9.1 Polylines</h4> |
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| 39 | |
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| 40 | A polyline is a set of successive line segments. It is defined with |
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| 41 | a class <i>G4Polyline</i> defined in the <tt>graphics_reps</tt> category. A polyline |
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| 42 | is used to visualize tracking steps, particle trajectories, coordinate |
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| 43 | axes, and any other user-defined objects made of line segments. |
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| 44 | <P> |
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| 45 | <i>G4Polyline</i> is defined as a list of <i>G4Point3D</i> objects, i.e., |
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| 46 | vertex positions. |
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| 47 | The vertex positions are set to a <i>G4Polyline</i> |
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| 48 | object with the <tt>push_back()</tt> method. |
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| 49 | <P> |
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| 50 | For example, an x-axis with length 5 cm and with red color is defined |
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| 51 | in Source listing 8.9.1. |
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| 52 | <P> |
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| 53 | <center> |
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| 54 | <table border=2 cellpadding=10> |
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| 55 | <tr> |
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| 56 | <td> |
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| 57 | <PRE> |
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| 58 | //----- C++ source codes: An example of defining a line segment |
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| 59 | // Instantiate an emply polyline object |
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| 60 | G4Polyline x_axis; |
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| 61 | |
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| 62 | // Set red line colour |
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| 63 | G4Colour red(1.0, 0.0, 0.0); |
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| 64 | G4VisAttributes att(red); |
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| 65 | x_axis.SetVisAttributes(&att); |
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| 66 | |
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| 67 | // Set vertex positions |
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| 68 | x_axis.push_back( G4Point3D(0., 0., 0.) ); |
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| 69 | x_axis.push_back( G4Point3D(5.*cm, 0., 0.) ); |
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| 70 | |
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| 71 | //----- end of C++ source codes |
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| 72 | </PRE> |
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| 73 | </td> |
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| 74 | </tr> |
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| 75 | <tr> |
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| 76 | <td align=center> |
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| 77 | Source listing 8.9.1<BR> |
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| 78 | Defining an x-axis with length 5 cm and with colour red. |
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| 79 | </td> |
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| 80 | </tr> |
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| 81 | </table></center> |
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| 82 | <P> |
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| 83 | |
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| 84 | <h4>8.9.2 Markers</h4> |
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| 85 | |
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| 86 | Here we explain how to use 3D markers in Geant4 Visualization. |
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| 87 | <p> |
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| 88 | <B>What are Markers?</B> |
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| 89 | <p> |
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| 90 | Markers set marks at arbitrary positions in the 3D space. They are often |
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| 91 | used to visualize hits of particles at detector components. A marker is |
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| 92 | a 2-dimensional primitive with shape (square, circle, etc), color, and |
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| 93 | special properties (a) of always facing the camera and (b) of having the |
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| 94 | possibility of a size defined in screen units (pixels). Here "size" means |
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| 95 | "overall size", e.g., diameter of circle and side of square (but diameter |
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| 96 | and radius access functions are defined to avoid ambiguity). |
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| 97 | <P> |
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| 98 | So the user who constructs a marker should decide whether or not it |
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| 99 | should be visualized to a given size in world coordinates by setting the |
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| 100 | world size. Alternatively, the user can set the screen size and the marker |
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| 101 | is visualized to its screen size. Finally, the user may decide not to set |
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| 102 | any size; in that case, it is drawn according to the sizes specified in |
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| 103 | the default marker specified in the class <i>G4ViewParameters</i>. |
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| 104 | <P> |
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| 105 | By default, "square" and "circle" are supported in Geant4 Visualization. |
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| 106 | The former is described with class <i>G4Square</i>, and the latter with class |
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| 107 | <i>G4Circle</i>: |
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| 108 | <p> |
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| 109 | <CENTER><TABLE BORDER=2 cellpadding=10> |
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| 110 | <TR> |
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| 111 | <TD><B>Marker Type</B></TD> |
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| 112 | <TD><B>Class Name</B></TD> |
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| 113 | </TR> |
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| 114 | <TR> |
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| 115 | <TD>circle</TD> |
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| 116 | <TD><i>G4Circle</i></TD> |
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| 117 | </TR> |
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| 118 | <TR> |
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| 119 | <TD>right square</TD> |
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| 120 | <TD><i>G4Square</i></TD> |
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| 121 | </TR> |
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| 122 | </TABLE></CENTER> |
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| 123 | <p> |
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| 124 | These classes are inherited from class <i>G4VMarker</i>. They have constructors |
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| 125 | as follows: |
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| 126 | <PRE> |
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| 127 | //----- Constructors of G4Circle and G4Square |
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| 128 | G4Circle::G4Circle (const G4Point3D& pos ); |
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| 129 | G4Square::G4Square (const G4Point3D& pos); |
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| 130 | </PRE> |
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| 131 | Access functions of class <i>G4VMarker</i> are summarized below. |
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| 132 | <p> |
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| 133 | <b>Access functions of markers</B> |
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| 134 | <P> |
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| 135 | Source listing 8.9.2 shows the access functions inherited from the base class <i>G4VMarker</i>. |
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| 136 | <P> |
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| 137 | <center> |
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| 138 | <table border=2 cellpadding=10> |
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| 139 | <tr> |
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| 140 | <td> |
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| 141 | <PRE> |
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| 142 | //----- Set functions of G4VMarker |
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| 143 | void G4VMarker::SetPosition( const G4Point3D& ); |
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| 144 | void G4VMarker::SetWorldSize( G4double ); |
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| 145 | void G4VMarker::SetWorldDiameter( G4double ); |
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| 146 | void G4VMarker::SetWorldRadius( G4double ); |
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| 147 | void G4VMarker::SetScreenSize( G4double ); |
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| 148 | void G4VMarker::SetScreenDiameter( G4double ); |
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| 149 | void G4VMarker::SetScreenRadius( G4double ); |
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| 150 | void G4VMarker::SetFillStyle( FillStyle ); |
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| 151 | // Note: enum G4VMarker::FillStyle {noFill, hashed, filled}; |
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| 152 | |
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| 153 | //----- Get functions of G4VMarker |
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| 154 | G4Point3D G4VMarker::GetPosition () const; |
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| 155 | G4double G4VMarker::GetWorldSize () const; |
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| 156 | G4double G4VMarker::GetWorldDiameter () const; |
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| 157 | G4double G4VMarker::GetWorldRadius () const; |
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| 158 | G4double G4VMarker::GetScreenSize () const; |
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| 159 | G4double G4VMarker::GetScreenDiameter () const; |
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| 160 | G4double G4VMarker::GetScreenRadius () const; |
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| 161 | FillStyle G4VMarker::GetFillStyle () const; |
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| 162 | // Note: enum G4VMarker::FillStyle {noFill, hashed, filled}; |
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| 163 | </PRE> |
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| 164 | </td> |
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| 165 | </tr> |
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| 166 | <tr> |
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| 167 | <td align=center> |
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| 168 | Source listing 8.9.2<BR> |
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| 169 | The access functions inherited from the base class <i>G4VMarker</i>. |
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| 170 | </td> |
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| 171 | </tr> |
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| 172 | </table></center> |
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| 173 | <P> |
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| 174 | Source listing 8.9.3 shows sample C++ source code to define a very small red circle, |
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| 175 | i.e., a dot with diameter 1.0 pixel. Such a dot is often used to visualize |
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| 176 | a hit. |
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| 177 | <P> |
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| 178 | <center> |
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| 179 | <table border=2 cellpadding=10> |
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| 180 | <tr> |
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| 181 | <td> |
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| 182 | <PRE> |
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| 183 | //----- C++ source codes: An example of defining a red small maker |
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| 184 | G4Circle circle(position); // Instantiate a circle with its 3D |
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| 185 | // position. The argument "position" |
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| 186 | // is defined as G4Point3D instance |
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| 187 | circle.SetScreenDiameter (1.0); // Should be circle.SetScreenDiameter |
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| 188 | // (1.0 * pixels) - to be implemented |
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| 189 | circle.SetFillStyle (G4Circle::filled); // Make it a filled circle |
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| 190 | G4Colour colour(1.,0.,0.); // Define red color |
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| 191 | G4VisAttributes attribs(colour); // Define a red visualization attribute |
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| 192 | circle.SetVisAttributes(attribs); // Assign the red attribute to the circle |
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| 193 | //----- end of C++ source codes |
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| 194 | </PRE> |
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| 195 | </td> |
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| 196 | </tr> |
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| 197 | <tr> |
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| 198 | <td align=center> |
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| 199 | Source listing 8.9.3<BR> |
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| 200 | Sample C++ source code to define a very small red circle. |
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| 201 | </td> |
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| 202 | </tr> |
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| 203 | </table></center> |
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| 204 | <P> |
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| 205 | |
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| 206 | <h4>8.9.3 Text</h4> |
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| 207 | |
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| 208 | Text, i.e., a character string, is used to visualize various kinds of description, |
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| 209 | particle name, energy, coordinate names etc. Text is described by the class |
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| 210 | <i>G4Text</i> . The following constructors are supported: |
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| 211 | <PRE> |
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| 212 | //----- Constructors of G4Text |
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| 213 | G4Text (const G4String& text); |
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| 214 | G4Text (const G4String& text, const G4Point3D& pos); |
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| 215 | </PRE> |
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| 216 | |
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| 217 | where the argument <tt>text</tt> is the text (string) to be visualized, and <tt>pos</tt> |
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| 218 | is the 3D position at which the text is visualized. |
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| 219 | <P> |
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| 220 | Note that class <i>G4Text</i> also inherits <i>G4VMarker</i>. Size of text is recognized |
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| 221 | as "font size", i.e., height of the text. All the access functions defined |
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| 222 | for class <i>G4VMarker</i> mentioned above are available. In addition, the following |
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| 223 | access functions are available, too: |
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| 224 | <PRE> |
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| 225 | //----- Set functions of G4Text |
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| 226 | void G4Text::SetText ( const G4String& text ) ; |
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| 227 | void G4Text::SetOffset ( double dx, double dy ) ; |
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| 228 | |
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| 229 | //----- Get functions of G4Text |
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| 230 | G4String G4Text::GetText () const; |
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| 231 | G4double G4Text::GetXOffset () const; |
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| 232 | G4double G4Text::GetYOffset () const; |
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| 233 | </PRE> |
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| 234 | |
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| 235 | Method <tt>SetText()</tt> defines text to be visualized, and <tt>GetText()</tt> returns the |
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| 236 | defined text. Method <tt>SetOffset()</tt> defines x (horizontal) and y (vertical) |
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| 237 | offsets in the screen coordinates. By default, both offsets are zero, and |
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| 238 | the text starts from the 3D position given to the constructor or to the |
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| 239 | method <tt>G4VMarker:SetPosition()</tt>. Offsets should be given with the same units |
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| 240 | as the one adopted for the size, i.e., world-size or screen-size units. |
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| 241 | <P> |
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| 242 | Source listing 8.9.4 shows sample C++ source code to define text with the following properties: |
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| 243 | |
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| 244 | <UL> |
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| 245 | <LI>Text: "Welcome to Geant4 Visualization"</LI> |
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| 246 | <LI>Position: (0.,0.,0.) in the world coordinates</LI> |
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| 247 | <LI>Horizontal offset: 10 pixels</LI> |
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| 248 | <LI>Vertical offset: -20 pixels</LI> |
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| 249 | <LI>Colour: blue (default)</LI> |
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| 250 | </UL> |
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| 251 | |
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| 252 | <P> |
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| 253 | <center> |
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| 254 | <table border=2 cellpadding=10> |
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| 255 | <tr> |
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| 256 | <td> |
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| 257 | <PRE> |
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| 258 | //----- C++ source codes: An example of defining a visualizable text |
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| 259 | |
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| 260 | //----- Instantiation |
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| 261 | G4Text text ; |
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| 262 | text.SetText ( "Welcome to Geant4 Visualization"); |
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| 263 | text.SetPosition ( G4Point3D(0.,0.,0.) ); |
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| 264 | // These three lines are equivalent to: |
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| 265 | // G4Text text ( "Welcome to Geant4 Visualization", |
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| 266 | // G4Point3D(0.,0.,0.) ); |
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| 267 | |
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| 268 | //----- Size (font size in units of pixels) |
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| 269 | G4double fontsize = 24.; // Should be 24. * pixels - to be implemented. |
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| 270 | text.SetScreenSize ( fontsize ); |
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| 271 | |
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| 272 | //----- Offsets |
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| 273 | G4double x_offset = 10.; // Should be 10. * pixels - to be implemented. |
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| 274 | G4double y_offset = -20.; // Should be -20. * pixels - to be implemented. |
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| 275 | text.SetOffset( x_offset, y_offset ); |
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| 276 | |
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| 277 | //----- Color (Blue is the default setting, and so the codes below are omissible) |
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| 278 | G4Colour blue( 0., 0., 1. ); |
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| 279 | G4VisAttributes att ( blue ); |
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| 280 | text.SetVisAttributes ( att ); |
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| 281 | |
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| 282 | //----- end of C++ source codes |
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| 283 | </PRE> |
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| 284 | </td> |
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| 285 | </tr> |
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| 286 | <tr> |
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| 287 | <td align=center> |
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| 288 | Source listing 8.9.4<BR> |
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| 289 | An example of defining text. |
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| 290 | </td> |
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| 291 | </tr> |
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| 292 | </table></center> |
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| 293 | <P> |
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| 294 | |
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| 295 | <HR> |
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