/// <summary>
/// Classifies the face based on the ray trace technique
/// </summary>
/// <param name="obj">object3d used to compute the face status</param>
public void RayTraceClassify(Object3D obj)
{
//creating a ray starting at the face baricenter going to the normal direction
Line ray = new Line(GetNormal(), center);
bool success;
double distance;
Vector3 intersectionPoint;
Face closestFace = null;
double closestDistance;
do
{
success = true;
closestDistance = Double.MaxValue;
//for each face from the other solid...
for (int faceIndex = 0; faceIndex < obj.GetNumFaces(); faceIndex++)
{
Face face = obj.GetFace(faceIndex);
intersectionPoint = ray.ComputePlaneIntersection(face.GetPlane());
//if ray intersects the plane...
if (intersectionPoint.x != double.PositiveInfinity)
{
double dotProduct = Vector3.Dot(face.GetNormal(), ray.Direction);
distance = ray.ComputePointToPointDistance(intersectionPoint);
//if ray lies in plane...
if (Math.Abs(distance) < EqualityTolerance && Math.Abs(dotProduct) < EqualityTolerance)
{
//disturb the ray in order to not lie into another plane
ray.PerturbDirection();
success = false;
break;
}
//if ray starts in plane...
if (Math.Abs(distance) < EqualityTolerance && Math.Abs(dotProduct) > EqualityTolerance)
{
//if ray intersects the face...
if (face.ContainsPoint(intersectionPoint))
{
//faces coincide
closestFace = face;
closestDistance = 0;
break;
}
}
//if ray intersects plane...
else if (Math.Abs(dotProduct) > EqualityTolerance && distance > EqualityTolerance)
{
if (distance < closestDistance)
{
//if ray intersects the face;
if (face.ContainsPoint(intersectionPoint))
{
//this face is the closest face until now
closestDistance = distance;
closestFace = face;
}
}
}
}
}
} while (success == false);
if (closestFace == null)
{
//none face found: outside face
status = Status.OUTSIDE;
}
else //face found: test dot product
{
double dotProduct = Vector3.Dot(closestFace.GetNormal(), ray.Direction);
//distance = 0: coplanar faces
if (Math.Abs(closestDistance) < EqualityTolerance)
{
if (dotProduct > EqualityTolerance)
{
status = Status.SAME;
}
else if (dotProduct < -EqualityTolerance)
{
status = Status.OPPOSITE;
}
}
else if (dotProduct > EqualityTolerance)
{
//dot product > 0 (same direction): inside face
status = Status.INSIDE;
}
else if (dotProduct < -EqualityTolerance)
{
//dot product < 0 (opposite direction): outside face
status = Status.OUTSIDE;
}
}
}
/// <summary>
/// 为表面分类，基于光线追踪技术
/// </summary>
/// <param name="obj">计算面状态的 3D 物件</param>
public void RayTraceClassify(Object3D obj)
{
Line ray = new Line(PlaneNormal, Center); // 射线从面的几何中心发出，方向为法线方向
Face closet = default;
bool foundCloset = false;
double closestDistance;
bool success;
do
{
success = true;
closestDistance = double.MaxValue;
for (int faceIndex = 0; faceIndex < obj.GetNumFaces(); faceIndex++)
{
Face face = obj.GetFace(faceIndex);
var intersectionPoint = ray.ComputePlaneIntersection(face.Plane); // 对三角面所在的平面采样
if (intersectionPoint.x < float.PositiveInfinity) // 射线被平面拦截
{
var distance = ray.ComputePointToPointDistance(intersectionPoint);
var dot = Vector3Double.Dot(face.PlaneNormal, ray.Direction);
bool parallel = Math.Abs(dot) < epsilon; // 射线与平面平行
//if ray lies in plane...
if (Math.Abs(distance) < epsilon) // 交点是射线起点
{
if (parallel)
{
// 略微抖动光线方向以免采样到另一平面
ray.PerturbDirection();
success = false;
break;
}
else if (face.ContainsPoint(intersectionPoint))
{
// 面重合
closet = face;
foundCloset = true;
closestDistance = 0;
break;
}
}
else if (!parallel && distance > epsilon) // 射线产生交点
{
if (distance < closestDistance && face.ContainsPoint(intersectionPoint))
{
closestDistance = distance;
closet = face; // 当前的面时最近的平面
foundCloset = true;
}
}
}
}
} while (!success);
if (!foundCloset)
{
Status = Status.OUTSIDE;
} // 没有找到面，自己是外部面
else // 由离自己最近的面，检查方向
{
var dot = Vector3Double.Dot(closet.PlaneNormal, ray.Direction);
if (Math.Abs(closestDistance) < epsilon) // 距离为零，这个面和自己重合
{
if (dot > epsilon)
{
Status = Status.SAME;
}
else if (dot < -epsilon)
{
Status = Status.OPPOSITE;
}
}
else if (dot > epsilon)
{
Status = Status.INSIDE;
} // 不重合，同向，在参数物件内部
else if (dot < -epsilon)
{
Status = Status.OUTSIDE;
} // 不重合，反向，在参数物件外部
}
}