示例#1
0
// Intersect ray r with the triangle abc.  If it hits returns true,
// and puts the t parameter, barycentric coordinates, normal, object id,
// and object material in the isect object
bool TrimeshFace::intersectLocal( const ray& r, isect& i ) const
{
  const Vec3d& a = parent->vertices[ids[0]];
  const Vec3d& b = parent->vertices[ids[1]];
  const Vec3d& c = parent->vertices[ids[2]];

  // tangent vectors
  Vec3d t1 = b - a;
  Vec3d t2 = c - a;
  
  Vec3d n = crossProd(t1,t2);

  double D = -n*a;

  // if the surface is parallel to the ray there is no intersection
  if(r.getDirection()*n == 0)
  {
    return false;
  }  

  double t = -(n*r.getPosition() + D)/(n*r.getDirection() );
  if (t <= RAY_EPSILON)
    return false;

  // point of intersection with the same plane (doesn't mean intersection with triangle) p(t)=p+t*d
  Vec3d p = r.at(t);

  // triangle area
  double A = n.length()/2.0;

  // barycentric coords
  double wa = crossProd(c-b, p-b).length() / (2.0*A);
  double wb = crossProd(a-c, p-c).length() / (2.0*A);
  double wc = crossProd(b-a, p-a).length() / (2.0*A);

  if((wa >= 0.0) && (wb >= 0.0) && (wc >= 0.0) && (wa+wb+wc-1.0 <= 0.00001)) {
    i.setT(t);
    i.setBary(wa, wb, wc);
    if (parent->normals.size() == 0) {
      i.setN(n);
    } else {
      Vec3d inter_n = wa*parent->normals[ids[0]] + wb*parent->normals[ids[1]]
                    + wc*parent->normals[ids[2]];
      inter_n.normalize();
      i.setN(inter_n);
    }
    i.setObject(this);
    if (parent->materials.size() == 0) {
      i.setMaterial(this->getMaterial() );
    } else {
      Material inter_m = wa*(*parent->materials[ids[0]]);
      inter_m += wb*(*parent->materials[ids[1]]);
      inter_m += wc*(*parent->materials[ids[2]]);
      i.setMaterial(inter_m);
    }
    return true;
  }

  return false;
}
示例#2
0
bool Box::intersectLocal( const ray& r, isect& i ) const
{

        Vec3d p = r.getPosition();
        Vec3d d = r.getDirection();

        int it;
        double x, y, t, bestT; 
        int mod0, mod1, mod2, bestIndex;

        bestT = HUGE_DOUBLE;
        bestIndex = -1;

        for(it=0; it<6; it++){ 
                mod0 = it%3;

                if(d[mod0] == 0){
                        continue;
                }
                
                t = ((it/3) - 0.5 - p[mod0]) / d[mod0];                 

                if(t < RAY_EPSILON || t > bestT){
                        continue;
                }

                mod1 = (it+1)%3;
                mod2 = (it+2)%3;
                x = p[mod1]+t*d[mod1];
                y = p[mod2]+t*d[mod2];
                
                if(     x<=0.5 && x>=-0.5 &&
                        y<=0.5 && y>=-0.5)
                {
                        if(bestT > t){
                                bestT = t;
                                bestIndex = it;
                        }
                }                       
                
        }

        if(bestIndex < 0) return false;
        
        i.setT(bestT);
        i.setObject(this);

		Vec3d intersect_point = r.at(i.t);

		int i1 = (bestIndex + 1) % 3;
		int i2 = (bestIndex + 2) % 3;

        if(bestIndex < 3)
		{
                i.setN(Vec3d(-double(bestIndex == 0), -double(bestIndex == 1), -double(bestIndex == 2)));
				i.setUVCoordinates( Vec2d(	0.5 - intersect_point[ min(i1, i2) ], 
											0.5 + intersect_point[ max(i1, i2) ] ) );
		}
        else
		{
                i.setN(Vec3d(double(bestIndex==3), double(bestIndex == 4), double(bestIndex == 5)));
				i.setUVCoordinates( Vec2d(	0.5 + intersect_point[ min(i1, i2) ],
											0.5 + intersect_point[ max(i1, i2) ] ) );

		}
        return true;

}