www.pudn.com > Ray_Tracing_Materials.rar > Sphere.cpp, change:2005-03-02,size:2761b

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


TraceResult Sphere::Intersect(Ray &ray)
{ 
   // result will hold the result of the test if the ray hits this sphere. 
   // RayToSphereDir will hold the direction of the ray's origin to the sphere origin. 
   TraceResult result;
   CVector4 RayToSphereDir; 
 
   // RayToSphereLength will hold the length of the ray's origin to the spheres origin. 
   // IntersectPoint will be greater than or equal to 0 if the ray hits the sphere. 
   // SquaredPoint will be used after the IntersectPoint test has turned up a hit. 
   float RayToSphereLength = 0.0f; 
   float IntersectPoint = 0.0f; 
   float SquaredPoint = 0.0f;
 
   // Get the direction of the ray to the current object we are testing against. 
   RayToSphereDir = center - ray.origin;
 
   // Dot product the direction of the ray to current sphere to get the length. 
   RayToSphereLength = RayToSphereDir.DotProduct3(RayToSphereDir); 
 
   // Get the dot product of the direction of the ray to the sphere with the direction the 
   // ray is moving to find the intersect point.
   IntersectPoint = RayToSphereDir.DotProduct3(ray.direction); 
 
   // If this is less than zero then the ray does not hit the sphere else it might.
   if(IntersectPoint < 0 )
      {
         result.hit = false;
         return result;
      }

   // Get the squared sphere radius - the length of the ray direction to the sphere 
   // plus the IntersectPoint squared.
   SquaredPoint = (radius * radius) - RayToSphereLength + 
                  (IntersectPoint * IntersectPoint);
 
   // If this is less than zero then the ray does not hit the sphere at all for sure.                                                         
   if(SquaredPoint < 0)
      {
         result.hit = false;
         return result;
      }
 
   // Else it does hit the sphere and we record the results.
   result.hit = true;
   result.distance = IntersectPoint - (float)sqrt(SquaredPoint); 
 
   return result;
} 
 
 
CVector4 Sphere::GetNormal(CVector4 &RayShapeIntersect) 
{ 
   CVector4 normal; 
 
   // Calculate the sphere normal at the point of intersection. 
   float oneOverRadius = 1 / radius; 
   normal.x = (RayShapeIntersect.x - center.x) * oneOverRadius; 
   normal.y = (RayShapeIntersect.y - center.y) * oneOverRadius; 
   normal.z = (RayShapeIntersect.z - center.z) * oneOverRadius; 
   normal.Normal(); 
 
   return normal; 
} 
 
 
// Copyright February 2005 
// All Rights Reserved! 
// Allen Sherrod 
// ProgrammingAce@UltimateGameProgramming.com 
// www.UltimateGameProgramming.com