/*
* 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.
*/
/**
* @class b2Distance
* @constructor
*/
var b2Distance = function () {
//
};
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
};
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;
