141 lines
2.8 KiB
C++
Executable File
141 lines
2.8 KiB
C++
Executable File
//***********************************************************
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//
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// Name: Plane.Cpp
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// Last Update: 17/2/02
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// Author: Poya Manouchehri
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//
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// Description: A Plane in R3 and several utility methods.
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// Note that the format used for the plane
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// equation is Ax + By + Cz + D = 0, where
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// <A,B,C> is the normal vector.
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//
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//***********************************************************
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#include "precompiled.h"
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#include "Plane.h"
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CPlane::CPlane ()
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{
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m_Norm.Clear ();
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m_Dist = 0.0f;
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}
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//sets the plane equation from 3 points on that plane
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void CPlane::Set (CVector3D &p1, CVector3D &p2, CVector3D &p3)
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{
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CVector3D D1, D2;
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CVector3D Norm;
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//calculate two vectors on the surface of the plane
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D1 = p2-p1;
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D2 = p3-p1;
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//cross multiply gives normal
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Norm = D2.Cross(D1);
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Set (Norm, p1);
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}
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//sets the plane equation from a normal and a point on
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//that plane
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void CPlane::Set (CVector3D &norm, CVector3D &point)
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{
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m_Norm = norm;
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m_Dist = - (norm.X * point.X +
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norm.Y * point.Y +
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norm.Z * point.Z);
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// Normalize ();
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}
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//normalizes the plane equation
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void CPlane::Normalize ()
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{
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float Scale;
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Scale = 1.0f/m_Norm.GetLength ();
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m_Norm.X *= Scale;
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m_Norm.Y *= Scale;
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m_Norm.Z *= Scale;
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m_Dist *= Scale;
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}
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//returns the side of the plane on which this point
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//lies.
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PLANESIDE CPlane::ClassifyPoint (const CVector3D &point) const
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{
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float Dist;
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Dist = m_Norm.X * point.X +
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m_Norm.Y * point.Y +
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m_Norm.Z * point.Z +
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m_Dist;
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if (Dist > 0.0f)
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return PS_FRONT;
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else if (Dist < 0.0f)
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return PS_BACK;
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return PS_ON;
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}
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//solves the plane equation for a particular point
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float CPlane::DistanceToPlane (const CVector3D &point) const
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{
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float Dist;
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Dist = m_Norm.X * point.X +
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m_Norm.Y * point.Y +
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m_Norm.Z * point.Z +
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m_Dist;
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return Dist;
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}
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//calculates the intersection point of a line with this
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//plane. Returns false if there is no intersection
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bool CPlane::FindLineSegIntersection (CVector3D &start, CVector3D &end, CVector3D *intsect)
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{
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PLANESIDE StartS, EndS;
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CVector3D Dir;
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float Length;
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//work out where each point is
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StartS = ClassifyPoint (start);
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EndS = ClassifyPoint (end);
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//if they are not on opposite sides of the plane return false
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if (StartS == EndS)
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return false;
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//work out a normalized vector in the direction start to end
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Dir = end - start;
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Dir.Normalize ();
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//a bit of algebra to work out how much we need to scale
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//this direction vector to get to the plane
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Length = -m_Norm.Dot(start)/m_Norm.Dot(Dir);
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//scale it by this amount
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Dir *= Length;
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//workout actual position vector of impact
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*intsect = start + Dir;
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return true;
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}
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bool CPlane::FindRayIntersection (CVector3D &start, CVector3D &direction, CVector3D *intsect)
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{
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float dot = m_Norm.Dot (direction);
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if (dot == 0.0f)
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return false;
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CVector3D a;
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*intsect = start - (direction * (DistanceToPlane (start)/dot));
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return true;
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}
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