1 // bbox_intersect.ysl2 |
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2 // |
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3 // bounding boxes intersection tests |
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4 |
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5 // Rates 1D intersection of 2 segments A and B |
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6 // described respectively with a0,a1 and b0,b1 |
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7 def "func:intersect_1d" { |
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8 // it is assumed that a1 > a0 and b1 > b0 |
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9 param "a0"; |
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10 param "a1"; |
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11 param "b0"; |
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12 param "b1"; |
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13 |
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14 const "d0", "$a0 >= $b0"; |
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15 const "d1", "$a1 >= $b1"; |
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16 choose { |
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17 when "not($d0) and $d1" |
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18 // b contained in a |
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19 // a0<b0 b1<a1 |
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20 // a +--------+ |
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21 // b +--+ |
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22 result "3"; |
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23 when "$d0 and not($d1)" |
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24 // a contained in b |
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25 // b0<a0 a1<b1 |
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26 // a +--+ |
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27 // b +--------+ |
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28 result "2"; |
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29 when "$d0 and $d1 and $a0 < $b1" |
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30 // a and b are overlapped |
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31 // b0<a0<b1<a1 |
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32 // a +-----+ |
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33 // b +-----+ |
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34 result "1"; |
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35 when "not($d0) and not($d1) and $b0 < $a1" |
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36 // a and b are overlapped |
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37 // a0<b0<a1<b1 |
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38 // a +-----+ |
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39 // b +-----+ |
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40 result "1"; |
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41 // since orientation doesn't matter, |
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42 // rated same as previous symetrical overlapping |
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43 otherwise |
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44 result "0"; /* no intersection*/ |
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45 } |
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46 } |
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47 |
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48 |
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49 // Rates intersection A and B areas described with x,y,w and h |
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50 // attributes passed as $a and $b parameters. |
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51 // |
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52 // returns : |
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53 // 0 - no intersection |
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54 // .-----. |
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55 // .-----. | b| |
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56 // | | | | |
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57 // | | '-----' |
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58 // |a | |
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59 // '-----' |
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60 // |
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61 // 1 - overlapping |
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62 // .-----. |
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63 // .---|--. b| |
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64 // | | | | |
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65 // | '-----' |
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66 // |a | |
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67 // '------' |
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68 // |
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69 // 2 - overlapping |
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70 // .-----. |
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71 // | a | |
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72 // .---|-----|---. |
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73 // | '-----' | |
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74 // | b | |
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75 // '-------------' |
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76 // |
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77 // 3 - overlapping |
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78 // .-----. |
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79 // | b | |
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80 // .---|-----|---. |
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81 // | '-----' | |
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82 // | a | |
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83 // '-------------' |
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84 // |
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85 // 4 - a contained in b |
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86 // .-------------. |
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87 // | .-----. | |
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88 // | | a | | |
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89 // |b '-----' | |
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90 // '-------------' |
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91 // |
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92 // 6 - overlapping |
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93 // .----. |
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94 // | b| |
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95 // .---|----|---. |
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96 // |a | | | |
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97 // '---|----|---' |
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98 // '----' |
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99 // |
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100 // 9 - b contained in a |
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101 // .-------------. |
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102 // | .-----. | |
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103 // | | b | | |
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104 // |a '-----' | |
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105 // '-------------' |
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106 // |
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107 def "func:intersect" { |
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108 param "a"; |
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109 param "b"; |
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110 |
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111 const "x_intersect", "func:intersect_1d($a/@x, $a/@x+$a/@w, $b/@x, $b/@x+$b/@w)"; |
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112 |
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113 choose{ |
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114 when "$x_intersect != 0"{ |
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115 const "y_intersect", "func:intersect_1d($a/@y, $a/@y+$a/@h, $b/@y, $b/@y+$b/@h)"; |
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116 result "$x_intersect * $y_intersect"; |
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117 } |
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118 otherwise result "0"; |
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119 } |
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120 } |
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