1 | // This file is a part of the Framsticks GDK library. |
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2 | // Copyright (C) 2002-2011 Szymon Ulatowski. See LICENSE.txt for details. |
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3 | // Refer to http://www.framsticks.com/ for further information. |
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4 | |
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5 | #ifndef _USERTAGS_H_ |
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6 | #define _USERTAGS_H_ |
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7 | |
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8 | /** |
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9 | UserTags is the fast way to associate custom data with general purpose objects. |
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10 | Objects don't have to know about their users and we can add more users later without recompilation. |
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11 | For example: MechObject is general physical object in MechaStick engine. |
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12 | In Framsticks simulator every MechObject is connected with Model object, MechParts and MechJoints are |
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13 | connected with their counterparts in the Model as well, but the MechObject doesn't even know about it. |
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14 | If the SSG visualisation is used, the same MechObject is also connected with SSGFramObject. |
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15 | UserTags class is implemented as array, therefore the access is very fast but we have to define |
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16 | maximum possible number of tags for every object: |
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17 | |
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18 | UserTags<anyclass,datatype,maximumtags> object; |
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19 | (all UserTags object for a given 'anyclass' will share registered id's) |
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20 | |
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21 | usage: |
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22 | 1.allocate private id: |
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23 | int id=object->userdata.newID(); |
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24 | 'id' is shared across all objects of that class (in this example) |
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25 | and therefore you need to allocate it only once. |
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26 | 0 is illegal here and means that we run out of id values. |
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27 | |
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28 | 2.now you can use id to access your private data inside UserTags: |
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29 | object->userdata[id]=...; |
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30 | ...=object->userdata[id]; |
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31 | ... |
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32 | 3.you can also assign/access object->userdata (which is a shortcut for |
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33 | object->userdata[0]). no id here, so in that case it is your responsibility |
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34 | to avoid conflicts. |
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35 | object->userdata=...; |
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36 | ...=object->userdata; |
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37 | ... |
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38 | |
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39 | 4.free your id when finished: |
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40 | object->userdata.freeID(id); |
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41 | */ |
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42 | |
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43 | template<class ID,class T,int N> class UserTags |
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44 | { |
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45 | static char reg[N]; |
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46 | T data[N]; |
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47 | public: |
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48 | UserTags() {memset(data,0,sizeof(data));} |
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49 | |
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50 | /** allocate new id */ |
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51 | static int newID() |
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52 | { for(int i=1;i<N;i++) if (!reg[i]) {reg[i]=1; return i;} |
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53 | DB(printf("Warning: UserTags run out of ids!\n")); |
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54 | return 0; } |
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55 | static void freeID(int id) |
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56 | { reg[id]=0; } |
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57 | T& operator[](int id) |
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58 | { |
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59 | DB(if (!id) printf("Warning: UserTags @ %p is using id=0\n",this);) |
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60 | return data[id]; |
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61 | } |
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62 | operator T() { return data[0]; } |
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63 | void operator=(T x) { data[0]=x; } |
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64 | }; |
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65 | |
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66 | #endif |
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67 | |
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68 | |
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69 | |
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70 | |
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71 | |
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