1 | #ifndef _Plane3_H__
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2 | #define _Plane3_H__
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3 |
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4 | #include "Vector3.h"
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5 |
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6 |
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7 | /** 3D Plane */
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8 | class Plane3 {
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9 | public:
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10 |
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11 | Vector3 mNormal;
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12 | float mD;
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13 |
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14 | Plane3() {}
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15 |
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16 | Plane3(const Vector3 &a,
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17 | const Vector3 &b,
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18 | const Vector3 &c
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19 | ) {
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20 | Vector3 v1=a-b, v2=c-b;
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21 | mNormal = Normalize(CrossProd(v2,v1));
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22 | mD = -DotProd(b, mNormal);
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23 | }
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24 |
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25 | Plane3(const Vector3 &normal,
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26 | const Vector3 &point
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27 | ):mNormal(normal)
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28 | {
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29 | mD = -DotProd(normal, point);
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30 | }
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31 |
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32 | void ReverseOrientation()
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33 | {
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34 | mNormal *= -1;
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35 | mD *= -1;
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36 | }
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37 |
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38 | float Distance(const Vector3 &v) const {
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39 | return DotProd(v, mNormal) + mD;
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40 | }
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41 |
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42 | int Side(const Vector3 &v, const float threshold = 1e-6) const {
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43 | return signum(Distance(v), threshold);
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44 | }
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45 |
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46 | /** Finds intersection of line segment between points a and b with plane.
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47 | @param a start point
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48 | @param b end point
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49 | @param t if not NULL, returns parameter value of intersections
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50 | @param coplanar if not NULL, returns true if plane and line segments are coplanar.
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51 | */
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52 | Vector3 FindIntersection(const Vector3 &a,
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53 | const Vector3 &b,
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54 | float *t = NULL,
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55 | bool *coplanar = NULL) const
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56 | {
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57 | const Vector3 v = b - a; // line from A to B
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58 | float dv = DotProd(v, mNormal);
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59 |
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60 | if (signum(dv) == 0)
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61 | {
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62 | if (coplanar) (*coplanar) = true;
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63 | if (t) (*t) = 0;
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64 | return a;
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65 | }
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66 |
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67 | if (coplanar) (*coplanar) = false;
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68 | float u = - Distance(a) / dv; // TODO: could be done more efficiently
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69 |
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70 | if (t) (*t) = u;
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71 |
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72 | return a + u * v;
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73 | }
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74 |
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75 | /** Finds value of intersection parameter t on line segment from a to b.
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76 | @returns -1 if coplanar, else parameter t
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77 | */
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78 | float FindT(const Vector3 &a, const Vector3 &b) const
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79 | {
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80 | const Vector3 v = b - a; // line from A to B
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81 | const float dv = DotProd(v, mNormal);
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82 |
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83 | // does not intersect or coincident
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84 | if (signum(dv) == 0)
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85 | return 0;
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86 |
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87 | return - Distance(a) / dv; // TODO: could be done more efficiently
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88 | }
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89 |
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90 | friend bool
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91 | PlaneIntersection(const Plane3 &a, const Plane3 &b, const Plane3 &c, Vector3 &result);
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92 |
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93 | friend ostream &operator<<(ostream &s, const Plane3 p) {
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94 | s<<p.mNormal<<" "<<p.mD;
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95 | return s;
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96 | }
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97 |
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98 |
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99 | };
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100 |
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101 |
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102 |
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103 |
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104 | #endif
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