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G4VCSGface.hh
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26 //
27 // $Id: G4VCSGface.hh 67011 2013-01-29 16:17:41Z gcosmo $
28 //
29 //
30 // --------------------------------------------------------------------
31 // GEANT 4 class header file
32 //
33 //
34 // G4VCSGface
35 //
36 // Class description:
37 //
38 // Definition of the virtual base class G4VCSGface, one side (or face)
39 // of a CSG-like solid. It should be possible to build a CSG entirely out of
40 // connecting CSG faces.
41 //
42 // Each face has an inside and outside surface, the former represents
43 // the inside of the volume, the latter, the outside.
44 //
45 // Virtual members:
46 //
47 // -------------------------------------------------------------------
48 // Intersect( const G4ThreeVector &p, const G4ThreeVector &v,
49 // G4bool outGoing, G4double surfTolerance,
50 // G4double &distance, G4double &distFromSurface,
51 // G4ThreeVector &normal, G4bool &allBehind );
52 //
53 // p - (in) position
54 // v - (in) direction (assumed to be a unit vector)
55 // outgoing - (in) true, to consider only inside surfaces
56 // false, to consider only outside surfaces
57 // distance - (out) distance to intersection
58 // distFromSurface - (out) distance from surface (along surface normal),
59 // < 0 if the point is in front of the surface
60 // normal - (out) normal of surface at intersection point
61 // allBehind - (out) true, if entire surface is behind normal
62 //
63 // return value = true if there is an intersection,
64 // false if there is no intersection
65 // (all output arguments undefined)
66 //
67 // Determine the distance along a line to the face.
68 //
69 // -------------------------------------------------------------------
70 // Distance( const G4ThreeVector &p, const G4bool outgoing );
71 //
72 // p - (in) position
73 // outgoing - (in) true, to consider only inside surfaces
74 // false, to consider only outside surfaces
75 //
76 // return value = distance to closest surface satisifying requirements
77 // or kInfinity if no such surface exists
78 //
79 // Determine the distance of a point from either the inside or outside
80 // surfaces of the face.
81 //
82 // -------------------------------------------------------------------
83 // Inside( const G4ThreeVector &p, const G4double tolerance,
84 // G4double *bestDistance );
85 //
86 // p - (in) position
87 // tolerance - (in) tolerance defining the bounds of the "kSurface",
88 // nominally equal to kCarTolerance/2
89 // bestDistance - (out) distance to closest surface (in or out)
90 //
91 // return value = kInside if the point is closest to the inside surface
92 // kOutside if the point is closest to the outside surface
93 // kSurface if the point is withing tolerance of the surface
94 //
95 // Determine whether a point is inside, outside, or on the surface of
96 // the face.
97 //
98 // -------------------------------------------------------------------
99 // Normal( const G4ThreeVector &p, G4double *bestDistance );
100 //
101 // p - (in) position
102 // bestDistance - (out) distance to closest surface (in or out)
103 //
104 // return value = the normal of the surface nearest the point
105 //
106 // Return normal of surface closest to the point.
107 //
108 // -------------------------------------------------------------------
109 // Extent( const G4ThreeVector axis );
110 //
111 // axis - (in) unit vector defining direction
112 //
113 // return value = the largest point along the given axis of the
114 // the face's extent.
115 //
116 // -------------------------------------------------------------------
117 // CalculateExtent( const EAxis pAxis,
118 // const G4VoxelLimit &pVoxelLimit,
119 // const G4AffineTransform &pTransform,
120 // G4double &min, G4double &max )
121 //
122 // pAxis - (in) The x,y, or z axis in which to check
123 // the shapes 3D extent against
124 // pVoxelLimit - (in) Limits along x, y, and/or z axes
125 // pTransform - (in) A coordinate transformation on which
126 // to apply to the shape before testing
127 // min - (out) If the face has any point on its
128 // surface after tranformation and limits
129 // along pAxis that is smaller than the value
130 // of min, than it is used to replace min.
131 // Undefined if the return value is false.
132 // max - (out) Same as min, except for the largest
133 // point.
134 // Undefined if the return value is false.
135 //
136 // return value = true if anything remains of the face
137 //
138 // Calculate the extent of the face for the voxel navigator.
139 // In analogy with CalculateExtent for G4VCSGfaceted, this is
140 // done in the following steps:
141 //
142 // 1. Transform the face using pTranform, an arbitrary 3D
143 // rotation/offset/reflection
144 // 2. Clip the face to those boundaries as specified in
145 // pVoxelLimit. This may include limits in any number
146 // of x, y, or z axes.
147 // 3. For each part of the face that remains (there could
148 // be many separate pieces in general):
149 // 4. Check to see if the piece overlaps the currently
150 // existing limits along axis pAxis. For
151 // pVoxelLimit.IsLimited(pAxis) = false, there are
152 // no limits.
153 // 5. For a piece that does overlap, update min/max
154 // accordingly (within confines of pre-existing
155 // limits) along the direction pAxis.
156 // 6. If min/max were updated, return true
157 //
158 // -------------------------------------------------------------------
159 // G3VCSGface *Clone()
160 //
161 // This method is invoked by G4CSGfaceted during the copy constructor
162 // or the assignment operator. Its purpose is to return a pointer
163 // (of type G4VCSGface) to a duplicate copy of the face.
164 // The implementation is straight forward for inherited classes. Example:
165 //
166 // G4VCSGface G4PolySideFace::Clone() { return new G4PolySideFace(*this); }
167 //
168 // Of course, this assumes the copy constructor of G4PolySideFace is
169 // correctly implemented.
170 //
171 // Implementation notes:
172 // * distance.
173 // The meaning of distance includes the boundaries of the face.
174 // For example, for a rectangular, planer face:
175 //
176 // A | B | C
177 // | |
178 // -------+--------------+-----
179 // D | I | E
180 // | |
181 // -------+--------------+-----
182 // F | G | H
183 // | |
184 //
185 // A, C, F, and H: closest distance is the distance to
186 // the adjacent corner.
187 //
188 // B, D, E, and G: closest distance is the distance to
189 // the adjacent line.
190 //
191 // I: normal distance to plane
192 //
193 // For non-planer faces, one can use the normal to decide when
194 // a point falls off the edge and then act accordingly.
195 //
196 //
197 // Usage:
198 //
199 // A CSG shape can be defined by putting together any number of generic
200 // faces, as long as the faces cover the entire surface of the shape
201 // without overlapping.
202 //
203 // G4VSolid::CalculateExtent
204 //
205 // Define unit vectors along the specified transform axis.
206 // Use the inverse of the specified coordinate transformation to rotate
207 // these unit vectors. Loop over each face, call face->Extent, and save
208 // the maximum value.
209 //
210 // G4VSolid::Inside
211 //
212 // To decide if a point is inside, outside, or on the surface of the shape,
213 // loop through all faces, and find the answer from face->Inside which gives
214 // a value of "bestDistance" smaller than any other. While looping, if any
215 // face->Inside returns kSurface, this value can be returned immediately.
216 //
217 // EInside answer;
218 // G4VCSGface *face = faces;
219 // G4double best = kInfinity;
220 // do {
221 // G4double distance;
222 // EInside result = (*face)->Inside( p, kCarTolerance/2, distance );
223 // if (result == kSurface) return kSurface;
224 // if (distance < best) {
225 // best = distance;
226 // answer = result;
227 // }
228 // } while( ++face < faces + numFaces );
229 //
230 // return(answer);
231 //
232 // G4VSolid::SurfaceNormal
233 //
234 // Loop over all faces, call face->Normal, and return the normal to the face
235 // that is closest to the point.
236 //
237 // G4VSolid::DistanceToIn(p)
238 //
239 // Loop over all faces, invoking face->Distance with outgoing = false,
240 // and save the answer that is smallest.
241 //
242 // G4VSolid::DistanceToIn(p,v)
243 //
244 // Loop over all faces, invoking face->Intersect with outgoing = false,
245 // and save the answer that is smallest.
246 //
247 // G4VSolid::DistanceToOut(p)
248 //
249 // Loop over all faces, invoking face->Distance with outgoing = true,
250 // and save the answer that is smallest.
251 //
252 // G4VSolid::DistanceToOut(p,v)
253 //
254 // Loop over all faces, invoking face->Intersect with outgoing = true,
255 // and save the answer that is smallest. If there is more than one answer,
256 // or if allBehind is false for the one answer, return validNorm as false.
257 
258 // Author:
259 // David C. Williams (davidw@scipp.ucsc.edu)
260 // --------------------------------------------------------------------
261 #ifndef G4VCSGface_hh
262 #define G4VCSGface_hh
263 
264 #include "G4Types.hh"
265 #include "G4ThreeVector.hh"
266 #include "geomdefs.hh"
267 #include "G4VSolid.hh"
268 
269 class G4VoxelLimits;
270 class G4AffineTransform;
271 class G4SolidExtentList;
272 
274 {
275  public: // with description
276 
278  virtual ~G4VCSGface() {}
279 
280  virtual G4bool Intersect( const G4ThreeVector &p, const G4ThreeVector &v,
281  G4bool outgoing, G4double surfTolerance,
282  G4double &distance, G4double &distFromSurface,
283  G4ThreeVector &normal, G4bool &allBehind ) = 0;
284 
285  virtual G4double Distance( const G4ThreeVector &p, G4bool outgoing ) = 0;
286 
287  virtual EInside Inside( const G4ThreeVector &p, G4double tolerance,
288  G4double *bestDistance ) = 0;
289 
290  virtual G4ThreeVector Normal( const G4ThreeVector &p,
291  G4double *bestDistance ) = 0;
292 
293  virtual G4double Extent( const G4ThreeVector axis ) = 0;
294 
295  virtual void CalculateExtent( const EAxis axis,
296  const G4VoxelLimits &voxelLimit,
297  const G4AffineTransform &tranform,
298  G4SolidExtentList &extentList ) = 0;
299 
300  virtual G4VCSGface* Clone() = 0;
301 
302  virtual G4double SurfaceArea( ) = 0;
303  virtual G4ThreeVector GetPointOnFace() = 0;
304 };
305 
306 #endif