C++ Plane::SignedDistance方法代码示例

bool Polyhedron::IsConvex() const
{
	// This function is O(n^2).
	/** @todo Real-Time Collision Detection, p. 64:
		A faster O(n) approach is to compute for each face F of P the centroid C of F,
		and for all neighboring faces G of F test if C lies behind the supporting plane of
		G. If some C fails to lie behind the supporting plane of one or more neighboring
		faces, P is concave, and is otherwise assumed convex. However, note that just as the
		corresponding polygonal convexity test may fail for a pentagram this test may fail for,
		for example, a pentagram extruded out of its plane and capped at the ends. */

	for(int f = 0; f < NumFaces(); ++f)
	{
		Plane p = FacePlane(f);
		for(int i = 0; i < NumVertices(); ++i)
		{
			float d = p.SignedDistance(Vertex(i));
			if (d > 1e-3f) // Tolerate a small epsilon error.
			{
				printf("Distance of vertex %d from plane %d: %f", i, f, d);
				return false;
			}
		}
	}
	return true;
}

bool Polygon::Intersects(const Plane &plane) const
{
	// Project the points of this polygon onto the 1D axis of the plane normal.
	// If there are points on both sides of the plane, then the polygon intersects the plane.
	float minD = inf;
	float maxD = -inf;
	for(size_t i = 0; i < p.size(); ++i)
	{
		float d = plane.SignedDistance(p[i]);
		minD = Min(minD, d);
		maxD = Max(maxD, d);
	}
	// Allow a very small epsilon tolerance.
	return minD <= 1e-4f && maxD >= -1e-4f;
}

void Polyhedron::MergeConvex(const float3 &point)
{
//	LOGI("mergeconvex.");
	std::set<std::pair<int, int> > deletedEdges;
	std::map<std::pair<int, int>, int> remainingEdges;

	for(size_t i = 0; i < v.size(); ++i)
		if (point.DistanceSq(v[i]) < 1e-3f)
			return;

//	bool hadDisconnectedHorizon = false;

	for(int i = 0; i < (int)f.size(); ++i)
	{
		// Delete all faces that don't contain the given point. (they have point in their positive side)
		Plane p = FacePlane(i);
		Face &face = f[i];
		if (p.SignedDistance(point) > 1e-5f)
		{
			bool isConnected = (deletedEdges.empty());

			int v0 = face.v.back();
			for(size_t j = 0; j < face.v.size() && !isConnected; ++j)
			{
				int v1 = face.v[j];
				if (deletedEdges.find(std::make_pair(v1, v0)) != deletedEdges.end())
				{
					isConnected = true;
					break;
				}
				v0 = v1;
			}

			if (isConnected)
			{
				v0 = face.v.back();
				for(size_t j = 0; j < face.v.size(); ++j)
				{
					int v1 = face.v[j];
					deletedEdges.insert(std::make_pair(v0, v1));
			//		LOGI("Edge %d,%d is to be deleted.", v0, v1);
					v0 = v1;
				}
		//		LOGI("Deleting face %d: %s. Distance to vertex %f", i, face.ToString().c_str(), p.SignedDistance(point));
				std::swap(f[i], f.back());
				f.pop_back();
				--i;
				continue;
			}
//			else
//				hadDisconnectedHorizon = true;
		}

		int v0 = face.v.back();
		for(size_t j = 0; j < face.v.size(); ++j)
		{
			int v1 = face.v[j];
			remainingEdges[std::make_pair(v0, v1)] = i;
	//		LOGI("Edge %d,%d is to be deleted.", v0, v1);
			v0 = v1;
		}

	}

	// The polyhedron contained our point, nothing to merge.
	if (deletedEdges.empty())
		return;

	// Add the new point to this polyhedron.
//	if (!v.back().Equals(point))
		v.push_back(point);

/*
	// Create a look-up index of all remaining uncapped edges of the polyhedron.
	std::map<std::pair<int,int>, int> edgesToFaces;
	for(size_t i = 0; i < f.size(); ++i)
	{
		Face &face = f[i];
		int v0 = face.v.back();
		for(size_t j = 0; j < face.v.size(); ++j)
		{
			int v1 = face.v[j];
			edgesToFaces[std::make_pair(v1, v0)] = i;
			v0 = v1;
		}
	}
*/
	// Now fix all edges by adding new triangular faces for the point.
//	for(size_t i = 0; i < deletedEdges.size(); ++i)
	for(std::set<std::pair<int, int> >::iterator iter = deletedEdges.begin(); iter != deletedEdges.end(); ++iter)
	{
		std::pair<int, int> opposite = std::make_pair(iter->second, iter->first);
		if (deletedEdges.find(opposite) != deletedEdges.end())
			continue;

//		std::map<std::pair<int,int>, int>::iterator iter = edgesToFaces.find(deletedEdges[i]);
//		std::map<std::pair<int,int>, int>::iterator iter = edgesToFaces.find(deletedEdges[i]);
//		if (iter != edgesToFaces.end())
		{
			// If the adjoining face is planar to the triangle we'd like to add, instead extend the face to enclose
//.........这里部分代码省略.........