source: GTP/trunk/Lib/Illum/GPUObscurancesGT/src/PLANE.cpp @ 930

Revision 930, 2.4 KB checked in by igarcia, 18 years ago (diff)
RevLine 
[930]1//////////////////////////////////////////////////////////////////////////////////////////
2//      PLANE.cpp
3//      function definitions for RGBA color class
4//      You may use this code however you wish, but if you do, please credit me and
5//      provide a link to my website in a readme file or similar
6//      Downloaded from: www.paulsprojects.net
7//      Created:        20th July 2002
8//      Modified:       6th August 2002 -       Added "Normalize"
9//                              7th November 2002       -       Altered constructor layout
10//                                                                      -       Corrected "lerp"
11//////////////////////////////////////////////////////////////////////////////////////////     
12
13#include "Maths.h"
14
15void PLANE::SetFromPoints(const VECTOR3D & p0, const VECTOR3D & p1, const VECTOR3D & p2)
16{
17        normal=(p1-p0).CrossProduct(p2-p0);
18
19        normal.Normalize();
20
21        CalculateIntercept(p0);
22}
23
24void PLANE::Normalize()
25{
26        float normalLength=normal.GetLength();
27        normal/=normalLength;
28        intercept/=normalLength;
29}
30
31bool PLANE::Intersect3(const PLANE & p2, const PLANE & p3, VECTOR3D & result)//find point of intersection of 3 planes
32{
33        float denominator=normal.DotProduct((p2.normal).CrossProduct(p3.normal));
34                                                                                        //scalar triple product of normals
35        if(denominator==0.0f)                                                                   //if zero
36                return false;                                                                           //no intersection
37
38        VECTOR3D temp1, temp2, temp3;
39        temp1=(p2.normal.CrossProduct(p3.normal))*intercept;
40        temp2=(p3.normal.CrossProduct(normal))*p2.intercept;
41        temp3=(normal.CrossProduct(p2.normal))*p3.intercept;
42
43        result=(temp1+temp2+temp3)/(-denominator);
44
45        return true;
46}
47
48float PLANE::GetDistance(const VECTOR3D & point) const
49{
50        return point.x*normal.x + point.y*normal.y + point.z*normal.z + intercept;
51}
52
53int PLANE::ClassifyPoint(const VECTOR3D & point) const
54{
55        float distance=point.x*normal.x + point.y*normal.y + point.z*normal.z + intercept;
56
57        if(distance>EPSILON)    //==0.0f is too exact, give a bit of room
58                return POINT_IN_FRONT_OF_PLANE;
59       
60        if(distance<-EPSILON)
61                return POINT_BEHIND_PLANE;
62
63        return POINT_ON_PLANE;  //otherwise
64}
65
66PLANE PLANE::lerp(const PLANE & p2, float factor)
67{
68        PLANE result;
69        result.normal=normal*(1.0f-factor) + p2.normal*factor;
70        result.normal.Normalize();
71
72        result.intercept=intercept*(1.0f-factor) + p2.intercept*factor;
73
74        return result;
75}
76
77bool PLANE::operator ==(const PLANE & rhs) const
78{
79        if(normal==rhs.normal && intercept==rhs.intercept)
80                return true;
81
82        return false;
83}
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