/*

* Copyright (c) 2006-2007 Erin Catto http:

*

* This software is provided 'as-is', without any express or implied

* warranty.  In no event will the authors be held liable for any damages

* arising from the use of this software.

* Permission is granted to anyone to use this software for any purpose,

* including commercial applications, and to alter it and redistribute it

* freely, subject to the following restrictions:

* 1. The origin of this software must not be misrepresented; you must not

* claim that you wrote the original software. If you use this software

* in a product, an acknowledgment in the product documentation would be

* appreciated but is not required.

* 2. Altered source versions must be plainly marked, and must not be

* misrepresented the original software.

* 3. This notice may not be removed or altered from any source distribution.

*/







var b2Distance = Class.create();

b2Distance.prototype = 

{



	// GJK using Voronoi regions (Christer Ericson) and region selection

	// optimizations (Casey Muratori).



	// The origin is either in the region of points[1] or in the edge region. The origin is

	// not in region of points[0] because that is the old point.



	// Possible regions:

	// - points[2]

	// - edge points[0]-points[2]

	// - edge points[1]-points[2]

	// - inside the triangle













	initialize: function() {}};

b2Distance.ProcessTwo = function(p1Out, p2Out, p1s, p2s, points)

	{

		// If in point[1] region

		//b2Vec2 r = -points[1];

		var rX = -points[1].x;

		var rY = -points[1].y;

		//b2Vec2 d = points[1] - points[0];

		var dX = points[0].x - points[1].x;

		var dY = points[0].y - points[1].y;

		//float32 length = d.Normalize();

		var length = Math.sqrt(dX*dX + dY*dY);

		dX /= length;

		dY /= length;



		//float32 lambda = b2Dot(r, d);

		var lambda = rX * dX + rY * dY;

		if (lambda <= 0.0 || length < Number.MIN_VALUE)

		{

			// The simplex is reduced to a point.

			//*p1Out = p1s[1];

			p1Out.SetV(p1s[1]);

			//*p2Out = p2s[1];

			p2Out.SetV(p2s[1]);

			//p1s[0] = p1s[1];

			p1s[0].SetV(p1s[1]);

			//p2s[0] = p2s[1];

			p2s[0].SetV(p2s[1]);

			points[0].SetV(points[1]);

			return 1;

		}



		// Else in edge region

		lambda /= length;

		//*p1Out = p1s[1] + lambda * (p1s[0] - p1s[1]);

		p1Out.x = p1s[1].x + lambda * (p1s[0].x - p1s[1].x);

		p1Out.y = p1s[1].y + lambda * (p1s[0].y - p1s[1].y);

		//*p2Out = p2s[1] + lambda * (p2s[0] - p2s[1]);

		p2Out.x = p2s[1].x + lambda * (p2s[0].x - p2s[1].x);

		p2Out.y = p2s[1].y + lambda * (p2s[0].y - p2s[1].y);

		return 2;

	};

b2Distance.ProcessThree = function(p1Out, p2Out, p1s, p2s, points)

	{

		//b2Vec2 a = points[0];

		var aX = points[0].x;

		var aY = points[0].y;

		//b2Vec2 b = points[1];

		var bX = points[1].x;

		var bY = points[1].y;

		//b2Vec2 c = points[2];

		var cX = points[2].x;

		var cY = points[2].y;



		//b2Vec2 ab = b - a;

		var abX = bX - aX;

		var abY = bY - aY;

		//b2Vec2 ac = c - a;

		var acX = cX - aX;

		var acY = cY - aY;

		//b2Vec2 bc = c - b;

		var bcX = cX - bX;

		var bcY = cY - bY;



		//float32 sn = -b2Dot(a, ab), sd = b2Dot(b, ab);

		var sn = -(aX * abX + aY * abY);

		var sd = (bX * abX + bY * abY);

		//float32 tn = -b2Dot(a, ac), td = b2Dot(c, ac);

		var tn = -(aX * acX + aY * acY);

		var td = (cX * acX + cY * acY);

		//float32 un = -b2Dot(b, bc), ud = b2Dot(c, bc);

		var un = -(bX * bcX + bY * bcY);

		var ud = (cX * bcX + cY * bcY);



		// In vertex c region?

		if (td <= 0.0 && ud <= 0.0)

		{

			// Single point

			//*p1Out = p1s[2];

			p1Out.SetV(p1s[2]);

			//*p2Out = p2s[2];

			p2Out.SetV(p2s[2]);

			//p1s[0] = p1s[2];

			p1s[0].SetV(p1s[2]);

			//p2s[0] = p2s[2];

			p2s[0].SetV(p2s[2]);

			points[0].SetV(points[2]);

			return 1;

		}



		// Should not be in vertex a or b region.

		//b2Settings.b2Assert(sn > 0.0 || tn > 0.0);

		//b2Settings.b2Assert(sd > 0.0 || un > 0.0);



		//float32 n = b2Cross(ab, ac);

		var n = abX * acY - abY * acX;



		// Should not be in edge ab region.

		//float32 vc = n * b2Cross(a, b);

		var vc = n * (aX * bY - aY * bX);

		//b2Settings.b2Assert(vc > 0.0 || sn > 0.0 || sd > 0.0);



		// In edge bc region?

		//float32 va = n * b2Cross(b, c);

		var va = n * (bX * cY - bY * cX);

		if (va <= 0.0 && un >= 0.0 && ud >= 0.0)

		{

			//b2Settings.b2Assert(un + ud > 0.0);



			//float32 lambda = un / (un + ud);

			var lambda = un / (un + ud);

			//*p1Out = p1s[1] + lambda * (p1s[2] - p1s[1]);

			p1Out.x = p1s[1].x + lambda * (p1s[2].x - p1s[1].x);

			p1Out.y = p1s[1].y + lambda * (p1s[2].y - p1s[1].y);

			//*p2Out = p2s[1] + lambda * (p2s[2] - p2s[1]);

			p2Out.x = p2s[1].x + lambda * (p2s[2].x - p2s[1].x);

			p2Out.y = p2s[1].y + lambda * (p2s[2].y - p2s[1].y);

			//p1s[0] = p1s[2];

			p1s[0].SetV(p1s[2]);

			//p2s[0] = p2s[2];

			p2s[0].SetV(p2s[2]);

			//points[0] = points[2];

			points[0].SetV(points[2]);

			return 2;

		}



		// In edge ac region?

		//float32 vb = n * b2Cross(c, a);

		var vb = n * (cX * aY - cY * aX);

		if (vb <= 0.0 && tn >= 0.0 && td >= 0.0)

		{

			//b2Settings.b2Assert(tn + td > 0.0);



			//float32 lambda = tn / (tn + td);

			var lambda = tn / (tn + td);

			//*p1Out = p1s[0] + lambda * (p1s[2] - p1s[0]);

			p1Out.x = p1s[0].x + lambda * (p1s[2].x - p1s[0].x);

			p1Out.y = p1s[0].y + lambda * (p1s[2].y - p1s[0].y);

			//*p2Out = p2s[0] + lambda * (p2s[2] - p2s[0]);

			p2Out.x = p2s[0].x + lambda * (p2s[2].x - p2s[0].x);

			p2Out.y = p2s[0].y + lambda * (p2s[2].y - p2s[0].y);

			//p1s[1] = p1s[2];

			p1s[1].SetV(p1s[2]);

			//p2s[1] = p2s[2];

			p2s[1].SetV(p2s[2]);

			//points[1] = points[2];

			points[1].SetV(points[2]);

			return 2;

		}



		// Inside the triangle, compute barycentric coordinates

		//float32 denom = va + vb + vc;

		var denom = va + vb + vc;

		//b2Settings.b2Assert(denom > 0.0);

		denom = 1.0 / denom;

		//float32 u = va * denom;

		var u = va * denom;

		//float32 v = vb * denom;

		var v = vb * denom;

		//float32 w = 1.0f - u - v;

		var w = 1.0 - u - v;

		//*p1Out = u * p1s[0] + v * p1s[1] + w * p1s[2];

		p1Out.x = u * p1s[0].x + v * p1s[1].x + w * p1s[2].x;

		p1Out.y = u * p1s[0].y + v * p1s[1].y + w * p1s[2].y;

		//*p2Out = u * p2s[0] + v * p2s[1] + w * p2s[2];

		p2Out.x = u * p2s[0].x + v * p2s[1].x + w * p2s[2].x;

		p2Out.y = u * p2s[0].y + v * p2s[1].y + w * p2s[2].y;

		return 3;

	};

b2Distance.InPoinsts = function(w, points, pointCount)

	{

		for (var i = 0; i < pointCount; ++i)

		{

			if (w.x == points[i].x && w.y == points[i].y)

			{

				return true;

			}

		}



		return false;

	};

b2Distance.Distance = function(p1Out, p2Out, shape1, shape2)

	{

		//b2Vec2 p1s[3], p2s[3];

		var p1s = new Array(3);

		var p2s = new Array(3);

		//b2Vec2 points[3];

		var points = new Array(3);

		//int32 pointCount = 0;

		var pointCount = 0;



		//*p1Out = shape1->m_position;

		p1Out.SetV(shape1.m_position);

		//*p2Out = shape2->m_position;

		p2Out.SetV(shape2.m_position);



		var vSqr = 0.0;

		var maxIterations = 20;

		for (var iter = 0; iter < maxIterations; ++iter)

		{

			//b2Vec2 v = *p2Out - *p1Out;

			var vX = p2Out.x - p1Out.x;

			var vY = p2Out.y - p1Out.y;

			//b2Vec2 w1 = shape1->Support(v);

			var w1 = shape1.Support(vX, vY);

			//b2Vec2 w2 = shape2->Support(-v);

			var w2 = shape2.Support(-vX, -vY);

			//float32 vSqr = b2Dot(v, v);

			vSqr = (vX*vX + vY*vY);

			//b2Vec2 w = w2 - w1;

			var wX = w2.x - w1.x;

			var wY = w2.y - w1.y;

			//float32 vw = b2Dot(v, w);

			var vw = (vX*wX + vY*wY);

			//if (vSqr - b2Dot(v, w) <= 0.01f * vSqr)

			if (vSqr - b2Dot(vX * wX + vY * wY) <= 0.01 * vSqr)

			{

				if (pointCount == 0)

				{

					//*p1Out = w1;

					p1Out.SetV(w1);

					//*p2Out = w2;

					p2Out.SetV(w2);

				}

				b2Distance.g_GJK_Iterations = iter;

				return Math.sqrt(vSqr);

			}



			switch (pointCount)

			{

			case 0:

				//p1s[0] = w1;

				p1s[0].SetV(w1);

				//p2s[0] = w2;

				p2s[0].SetV(w2);

				points[0] = w;

				//*p1Out = p1s[0];

				p1Out.SetV(p1s[0]);

				//*p2Out = p2s[0];

				p2Out.SetV(p2s[0]);

				++pointCount;

				break;



			case 1:

				//p1s[1] = w1;

				p1s[1].SetV(w1);

				//p2s[1] = w2;

				p2s[1].SetV(w2);

				//points[1] = w;

				points[1].x = wX;

				points[1].y = wY;

				pointCount = b2Distance.ProcessTwo(p1Out, p2Out, p1s, p2s, points);

				break;



			case 2:

				//p1s[2] = w1;

				p1s[2].SetV(w1);

				//p2s[2] = w2;

				p2s[2].SetV(w2);

				//points[2] = w;

				points[2].x = wX;

				points[2].y = wY;

				pointCount = b2Distance.ProcessThree(p1Out, p2Out, p1s, p2s, points);

				break;

			}



			// If we have three points, then the origin is in the corresponding triangle.

			if (pointCount == 3)

			{

				b2Distance.g_GJK_Iterations = iter;

				return 0.0;

			}



			//float32 maxSqr = -FLT_MAX;

			var maxSqr = -Number.MAX_VALUE;

			for (var i = 0; i < pointCount; ++i)

			{

				//maxSqr = b2Math.b2Max(maxSqr, b2Dot(points[i], points[i]));

				maxSqr = b2Math.b2Max(maxSqr, (points[i].x*points[i].x + points[i].y*points[i].y));

			}



			if (pointCount == 3 || vSqr <= 100.0 * Number.MIN_VALUE * maxSqr)

			{

				b2Distance.g_GJK_Iterations = iter;

				return Math.sqrt(vSqr);

			}

		}



		b2Distance.g_GJK_Iterations = maxIterations;

		return Math.sqrt(vSqr);

	};

b2Distance.g_GJK_Iterations = 0;