www.pudn.com > Ray_Tracing_Materials.rar > Triangle.cpp, change:2005-03-02,size:2147b

/* 
   File Name: 
 
      Triangle.cpp 
 
   Created by: 
 
      Allen Sherrod (Programming Ace of www.UltimateGameProgramming.com). 
 
   Description: 
 
      This file has the source for the Triangle class functions. 
*/ 
 
 
#include"Triangle.h" 


TraceResult Triangle::Intersect(Ray &ray)
{ 
   // result will hold the result of the test if the ray hits this triangle. 
   TraceResult result;
   result.hit = false;
   
   // Store these vectors between the points for future use.
   CVector4 vecAB = p2 - p1;
   CVector4 vecAC = p3 - p1;

   // Get the corss product bewteen the p3 - p1 vector and the ray direction.
   CVector4 cross;
   cross.CrossProduct(ray.direction, vecAC);
   
   // Calculate the determinate.
   float det = vecAB.DotProduct3(cross);
   
   // If the dot product between the cross product result and the vector
   // between point 2 and 1 is 0 or less than 0, the ray does not hit.
   if(det < 0.0001f)
      {
         result.hit = false;
         return result;
      }
      
   CVector4 rayPointVec = ray.origin - p1;
   float test1 = rayPointVec.DotProduct3(cross);
   
   // Ray must be behind the plane of the triangle if these are true.
   if(test1 < 0.0f || test1 > det)
      {
         result.hit = false;
         return result;
      }
   
   CVector4 cross2;
   cross2.CrossProduct(rayPointVec , vecAB);
   float test2 = ray.direction.DotProduct3(cross2);

   // If the second test is less than 0 or if test1 + test2 is > det
   // then we don't have a hit.
   if(test2 < 0.0f || test1 + test2 > det)
      {
         result.hit = false;
         return result;
      }
   
   // Else we have a hit and can calculate the distance of intersection.
   float inverseDet = 1.0f / det;
   result.distance = vecAC.DotProduct3(cross2);
   result.distance *= inverseDet;
   result.hit = true;
 
   return result;
} 
 
 
CVector4 Triangle::GetNormal()
{
	CVector4 normal;
	normal.CrossProduct(p2 - p1, p3 - p1);
	normal.Normal();

   return normal;
} 
 
 
// Copyright February 2005 
// All Rights Reserved! 
// Allen Sherrod 
// ProgrammingAce@UltimateGameProgramming.com 
// www.UltimateGameProgramming.com