svn merge -r83872:83893 linden/branches/Branch_1-20-0-Server to linden/release

HAVOK4 IN TEH HOUSE!!11!!ONE!!
If it is broken blame Joel for not fixing the loginassetdatabaseinventorygroupIM server instead of working on this.

QAR-448

1 files changed, 351 insertions, 0 deletions

diff --git a/indra/llmath/llsphere.cpp b/indra/llmath/llsphere.cpp
new file mode 100644
index 0000000000..3428dc1487
--- /dev/null
+++ b/indra/llmath/llsphere.cpp
@@ -0,0 +1,351 @@
+/** 
+ * @file llsphere.cpp
+ * @author Andrew Meadows
+ * @brief Simple line class that can compute nearest approach between two lines
+ *
+ * Copyright (c) 2006-$CurrentYear$, Linden Research, Inc.
+ * $License$
+ */
+
+#include "llsphere.h"
+
+LLSphere::LLSphere()
+:	mCenter(0.f, 0.f, 0.f),
+	mRadius(0.f)
+{ }
+
+LLSphere::LLSphere( const LLVector3& center, F32 radius)
+{
+	set(center, radius);
+}
+
+void LLSphere::set( const LLVector3& center, F32 radius )
+{
+	mCenter = center;
+	setRadius(radius);
+}
+
+void LLSphere::setCenter( const LLVector3& center)
+{
+	mCenter = center;
+}
+
+void LLSphere::setRadius( F32 radius)
+{
+	if (radius < 0.f)
+	{
+		radius = -radius;
+	}
+	mRadius = radius;
+}
+	
+const LLVector3& LLSphere::getCenter() const
+{
+	return mCenter;
+}
+
+F32 LLSphere::getRadius() const
+{
+	return mRadius;
+}
+
+// returns 'TRUE' if this sphere completely contains other_sphere
+BOOL LLSphere::contains(const LLSphere& other_sphere) const
+{
+	F32 separation = (mCenter - other_sphere.mCenter).length();
+	return (mRadius >= separation + other_sphere.mRadius) ? TRUE : FALSE;
+}
+
+// returns 'TRUE' if this sphere completely contains other_sphere
+BOOL LLSphere::overlaps(const LLSphere& other_sphere) const
+{
+	F32 separation = (mCenter - other_sphere.mCenter).length();
+	return (separation <= mRadius + other_sphere.mRadius) ? TRUE : FALSE;
+}
+
+// returns overlap
+// negative overlap is closest approach
+F32 LLSphere::getOverlap(const LLSphere& other_sphere) const
+{
+	// separation is distance from other_sphere's edge and this center
+	return (mCenter - other_sphere.mCenter).length() - mRadius - other_sphere.mRadius;
+}
+
+bool LLSphere::operator==(const LLSphere& rhs) const
+{
+	// TODO? -- use approximate equality for centers?
+	return (mRadius == rhs.mRadius
+			&& mCenter == rhs.mCenter);
+}
+
+std::ostream& operator<<( std::ostream& output_stream, const LLSphere& sphere)
+{
+	output_stream << "{center=" << sphere.mCenter << "," << "radius=" << sphere.mRadius << "}";
+	return output_stream;
+}
+
+// static 
+// removes any spheres that are contained in others
+void LLSphere::collapse(std::vector<LLSphere>& sphere_list)
+{
+	std::vector<LLSphere>::iterator first_itr = sphere_list.begin();
+	while (first_itr != sphere_list.end())
+	{
+		bool delete_from_front = false;
+
+		std::vector<LLSphere>::iterator second_itr = first_itr;
+		++second_itr;
+		while (second_itr != sphere_list.end())
+		{
+			if (second_itr->contains(*first_itr))
+			{
+				delete_from_front = true;
+				break;
+			}
+			else if (first_itr->contains(*second_itr))
+			{
+				sphere_list.erase(second_itr++);
+			}
+			else
+			{
+				++second_itr;
+			}
+		}
+
+		if (delete_from_front)
+		{
+			sphere_list.erase(first_itr++);
+		}
+		else
+		{
+			++first_itr;
+		}
+	}
+}
+
+// static
+// returns the bounding sphere that contains both spheres
+LLSphere LLSphere::getBoundingSphere(const LLSphere& first_sphere, const LLSphere& second_sphere)
+{
+	LLVector3 direction = second_sphere.mCenter - first_sphere.mCenter;
+
+	// HACK -- it is possible to get enough floating point error in the 
+	// other getBoundingSphere() method that we have to add some slop
+	// at the end.  Unfortunately, this breaks the link-order invarience
+	// for the linkability tests... unless we also apply the same slop
+	// here.
+	F32 half_milimeter = 0.0005f;
+
+	F32 distance = direction.length();
+	if (0.f == distance)
+	{
+		direction.setVec(1.f, 0.f, 0.f);
+	}
+	else
+	{
+		direction.normVec();
+	}
+	// the 'edge' is measured from the first_sphere's center
+	F32 max_edge = 0.f;
+	F32 min_edge = 0.f;
+
+	max_edge = llmax(max_edge + first_sphere.getRadius(), max_edge + distance + second_sphere.getRadius() + half_milimeter);
+	min_edge = llmin(min_edge - first_sphere.getRadius(), min_edge + distance - second_sphere.getRadius() - half_milimeter);
+	F32 radius = 0.5f * (max_edge - min_edge);
+	LLVector3 center = first_sphere.mCenter + (0.5f * (max_edge + min_edge)) * direction;
+	return LLSphere(center, radius);
+}
+
+// static
+// returns the bounding sphere that contains an arbitrary set of spheres
+LLSphere LLSphere::getBoundingSphere(const std::vector<LLSphere>& sphere_list)
+{
+	// this algorithm can get relatively inaccurate when the sphere 
+	// collection is 'small' (contained within a bounding sphere of about 
+	// 2 meters or less)
+	// TODO -- improve the accuracy for small collections of spheres
+
+	LLSphere bounding_sphere( LLVector3(0.f, 0.f, 0.f), 0.f );
+	S32 sphere_count = sphere_list.size();
+	if (1 == sphere_count)
+	{
+		// trivial case -- single sphere
+		std::vector<LLSphere>::const_iterator sphere_itr = sphere_list.begin();
+		bounding_sphere = *sphere_itr;
+	}
+	else if (2 == sphere_count)
+	{
+		// trivial case -- two spheres
+		std::vector<LLSphere>::const_iterator first_sphere = sphere_list.begin();
+		std::vector<LLSphere>::const_iterator second_sphere = first_sphere;
+		++second_sphere;
+		bounding_sphere = LLSphere::getBoundingSphere(*first_sphere, *second_sphere);
+	}
+	else if (sphere_count > 0)
+	{
+		// non-trivial case -- we will approximate the solution
+		//
+		// NOTE -- there is a fancy/fast way to do this for large 
+		// numbers of arbirary N-dimensional spheres -- you can look it
+		// up on the net.  We're dealing with 3D spheres at collection
+		// sizes of 256 spheres or smaller, so we just use this
+		// brute force method.
+
+		// TODO -- perhaps would be worthwile to test for the solution where
+		// the largest spanning radius just happens to work.  That is, where
+		// there are really two spheres that determine the bounding sphere,
+		// and all others are contained therein.
+
+		// compute the AABB
+		std::vector<LLSphere>::const_iterator first_itr = sphere_list.begin();
+		LLVector3 max_corner = first_itr->getCenter() + first_itr->getRadius() * LLVector3(1.f, 1.f, 1.f);
+		LLVector3 min_corner = first_itr->getCenter() - first_itr->getRadius() * LLVector3(1.f, 1.f, 1.f);
+		{
+			std::vector<LLSphere>::const_iterator sphere_itr = sphere_list.begin();
+			for (++sphere_itr; sphere_itr != sphere_list.end(); ++sphere_itr)
+			{
+				LLVector3 center = sphere_itr->getCenter();
+				F32 radius = sphere_itr->getRadius();
+				for (S32 i=0; i<3; ++i)
+				{
+					if (center.mV[i] + radius > max_corner.mV[i])
+					{
+						max_corner.mV[i] = center.mV[i] + radius;
+					}
+					if (center.mV[i] - radius < min_corner.mV[i])
+					{
+						min_corner.mV[i] = center.mV[i] - radius;
+					}
+				}
+			}
+		}
+
+		// get the starting center and radius from the AABB
+		LLVector3 diagonal = max_corner - min_corner;
+		F32 bounding_radius = 0.5f * diagonal.length();
+		LLVector3 bounding_center = 0.5f * (max_corner + min_corner);
+
+		// compute the starting step-size
+		F32 minimum_radius = 0.5f * llmin(diagonal.mV[VX], llmin(diagonal.mV[VY], diagonal.mV[VZ]));
+		F32 step_length = bounding_radius - minimum_radius;
+		S32 step_count = 0;
+		S32 max_step_count = 12;
+		F32 half_milimeter = 0.0005f;
+
+		// wander the center around in search of tighter solutions
+		S32 last_dx = 2;	// 2 is out of bounds --> no match
+		S32 last_dy = 2;
+		S32 last_dz = 2;
+
+		while (step_length > half_milimeter
+				&& step_count < max_step_count)
+		{
+			// the algorithm for testing the maximum radius could be expensive enough
+			// that it makes sense to NOT duplicate testing when possible, so we keep
+			// track of where we last tested, and only test the new points
+
+			S32 best_dx = 0;
+			S32 best_dy = 0;
+			S32 best_dz = 0;
+
+			// sample near the center of the box
+			bool found_better_center = false;
+			for (S32 dx = -1; dx < 2; ++dx)
+			{
+				for (S32 dy = -1; dy < 2; ++dy)
+				{
+					for (S32 dz = -1; dz < 2; ++dz)
+					{
+						if (dx == 0 && dy == 0 && dz == 0)
+						{
+							continue;
+						}
+
+						// count the number of indecies that match the last_*'s
+						S32 match_count = 0;
+						if (last_dx == dx) ++match_count;
+						if (last_dy == dy) ++match_count;
+						if (last_dz == dz) ++match_count;
+						if (match_count == 2)
+						{
+							// we've already tested this point
+							continue;
+						}
+
+						LLVector3 center = bounding_center;
+						center.mV[VX] += (F32) dx * step_length;
+						center.mV[VY] += (F32) dy * step_length;
+						center.mV[VZ] += (F32) dz * step_length;
+
+						// compute the radius of the bounding sphere
+						F32 max_radius = 0.f;
+						std::vector<LLSphere>::const_iterator sphere_itr;
+						for (sphere_itr = sphere_list.begin(); sphere_itr != sphere_list.end(); ++sphere_itr)
+						{
+							F32 radius = (sphere_itr->getCenter() - center).length() + sphere_itr->getRadius();
+							if (radius > max_radius)
+							{
+								max_radius = radius;
+							}
+						}
+						if (max_radius < bounding_radius)
+						{
+							best_dx = dx;
+							best_dy = dy;
+							best_dz = dz;
+							bounding_center = center;
+							bounding_radius = max_radius;
+							found_better_center = true;
+						}
+					}
+				}
+			}
+			if (found_better_center)
+			{
+				// remember where we came from so we can avoid retesting
+				last_dx = -best_dx;
+				last_dy = -best_dy;
+				last_dz = -best_dz;
+			}
+			else
+			{
+				// reduce the step size
+				step_length *= 0.5f;
+				//++step_count;
+				// reset the last_*'s
+				last_dx = 2;	// 2 is out of bounds --> no match
+				last_dy = 2;
+				last_dz = 2;
+			}
+		}
+
+		// HACK -- it is possible to get enough floating point error for the
+		// bounding sphere to too small on the order of 10e-6, but we only need
+		// it to be accurate to within about half a millimeter
+		bounding_radius += half_milimeter;
+
+		// this algorithm can get relatively inaccurate when the sphere 
+		// collection is 'small' (contained within a bounding sphere of about 
+		// 2 meters or less)
+		// TODO -- fix this
+		/* debug code
+		{
+			std::vector<LLSphere>::const_iterator sphere_itr;
+			for (sphere_itr = sphere_list.begin(); sphere_itr != sphere_list.end(); ++sphere_itr)
+			{
+				F32 radius = (sphere_itr->getCenter() - bounding_center).length() + sphere_itr->getRadius();
+				if (radius + 0.1f > bounding_radius)
+				{
+					std::cout << " rad = " << radius << "  bounding - rad = " << (bounding_radius - radius) << std::endl;
+				}
+			}
+			std::cout << "\n" << std::endl;
+		}
+		*/ 
+
+		bounding_sphere.set(bounding_center, bounding_radius);
+	}
+	return bounding_sphere;
+}
+
+