334 lines
9.2 KiB
JavaScript
334 lines
9.2 KiB
JavaScript
/*
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* Copyright (c) 2006-2007 Erin Catto http:
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked, and must not be
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* misrepresented the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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var b2Distance = Class.create();
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b2Distance.prototype =
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{
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// GJK using Voronoi regions (Christer Ericson) and region selection
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// optimizations (Casey Muratori).
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// The origin is either in the region of points[1] or in the edge region. The origin is
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// not in region of points[0] because that is the old point.
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// Possible regions:
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// - points[2]
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// - edge points[0]-points[2]
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// - edge points[1]-points[2]
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// - inside the triangle
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initialize: function() {}};
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b2Distance.ProcessTwo = function(p1Out, p2Out, p1s, p2s, points)
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{
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// If in point[1] region
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//b2Vec2 r = -points[1];
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var rX = -points[1].x;
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var rY = -points[1].y;
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//b2Vec2 d = points[1] - points[0];
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var dX = points[0].x - points[1].x;
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var dY = points[0].y - points[1].y;
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//float32 length = d.Normalize();
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var length = Math.sqrt(dX*dX + dY*dY);
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dX /= length;
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dY /= length;
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//float32 lambda = b2Dot(r, d);
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var lambda = rX * dX + rY * dY;
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if (lambda <= 0.0 || length < Number.MIN_VALUE)
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{
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// The simplex is reduced to a point.
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//*p1Out = p1s[1];
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p1Out.SetV(p1s[1]);
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//*p2Out = p2s[1];
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p2Out.SetV(p2s[1]);
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//p1s[0] = p1s[1];
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p1s[0].SetV(p1s[1]);
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//p2s[0] = p2s[1];
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p2s[0].SetV(p2s[1]);
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points[0].SetV(points[1]);
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return 1;
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}
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// Else in edge region
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lambda /= length;
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//*p1Out = p1s[1] + lambda * (p1s[0] - p1s[1]);
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p1Out.x = p1s[1].x + lambda * (p1s[0].x - p1s[1].x);
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p1Out.y = p1s[1].y + lambda * (p1s[0].y - p1s[1].y);
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//*p2Out = p2s[1] + lambda * (p2s[0] - p2s[1]);
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p2Out.x = p2s[1].x + lambda * (p2s[0].x - p2s[1].x);
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p2Out.y = p2s[1].y + lambda * (p2s[0].y - p2s[1].y);
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return 2;
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};
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b2Distance.ProcessThree = function(p1Out, p2Out, p1s, p2s, points)
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{
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//b2Vec2 a = points[0];
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var aX = points[0].x;
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var aY = points[0].y;
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//b2Vec2 b = points[1];
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var bX = points[1].x;
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var bY = points[1].y;
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//b2Vec2 c = points[2];
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var cX = points[2].x;
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var cY = points[2].y;
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//b2Vec2 ab = b - a;
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var abX = bX - aX;
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var abY = bY - aY;
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//b2Vec2 ac = c - a;
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var acX = cX - aX;
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var acY = cY - aY;
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//b2Vec2 bc = c - b;
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var bcX = cX - bX;
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var bcY = cY - bY;
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//float32 sn = -b2Dot(a, ab), sd = b2Dot(b, ab);
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var sn = -(aX * abX + aY * abY);
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var sd = (bX * abX + bY * abY);
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//float32 tn = -b2Dot(a, ac), td = b2Dot(c, ac);
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var tn = -(aX * acX + aY * acY);
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var td = (cX * acX + cY * acY);
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//float32 un = -b2Dot(b, bc), ud = b2Dot(c, bc);
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var un = -(bX * bcX + bY * bcY);
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var ud = (cX * bcX + cY * bcY);
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// In vertex c region?
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if (td <= 0.0 && ud <= 0.0)
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{
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// Single point
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//*p1Out = p1s[2];
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p1Out.SetV(p1s[2]);
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//*p2Out = p2s[2];
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p2Out.SetV(p2s[2]);
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//p1s[0] = p1s[2];
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p1s[0].SetV(p1s[2]);
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//p2s[0] = p2s[2];
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p2s[0].SetV(p2s[2]);
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points[0].SetV(points[2]);
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return 1;
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}
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// Should not be in vertex a or b region.
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//b2Settings.b2Assert(sn > 0.0 || tn > 0.0);
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//b2Settings.b2Assert(sd > 0.0 || un > 0.0);
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//float32 n = b2Cross(ab, ac);
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var n = abX * acY - abY * acX;
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// Should not be in edge ab region.
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//float32 vc = n * b2Cross(a, b);
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var vc = n * (aX * bY - aY * bX);
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//b2Settings.b2Assert(vc > 0.0 || sn > 0.0 || sd > 0.0);
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// In edge bc region?
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//float32 va = n * b2Cross(b, c);
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var va = n * (bX * cY - bY * cX);
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if (va <= 0.0 && un >= 0.0 && ud >= 0.0)
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{
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//b2Settings.b2Assert(un + ud > 0.0);
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//float32 lambda = un / (un + ud);
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var lambda = un / (un + ud);
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//*p1Out = p1s[1] + lambda * (p1s[2] - p1s[1]);
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p1Out.x = p1s[1].x + lambda * (p1s[2].x - p1s[1].x);
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p1Out.y = p1s[1].y + lambda * (p1s[2].y - p1s[1].y);
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//*p2Out = p2s[1] + lambda * (p2s[2] - p2s[1]);
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p2Out.x = p2s[1].x + lambda * (p2s[2].x - p2s[1].x);
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p2Out.y = p2s[1].y + lambda * (p2s[2].y - p2s[1].y);
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//p1s[0] = p1s[2];
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p1s[0].SetV(p1s[2]);
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//p2s[0] = p2s[2];
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p2s[0].SetV(p2s[2]);
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//points[0] = points[2];
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points[0].SetV(points[2]);
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return 2;
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}
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// In edge ac region?
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//float32 vb = n * b2Cross(c, a);
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var vb = n * (cX * aY - cY * aX);
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if (vb <= 0.0 && tn >= 0.0 && td >= 0.0)
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{
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//b2Settings.b2Assert(tn + td > 0.0);
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//float32 lambda = tn / (tn + td);
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var lambda = tn / (tn + td);
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//*p1Out = p1s[0] + lambda * (p1s[2] - p1s[0]);
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p1Out.x = p1s[0].x + lambda * (p1s[2].x - p1s[0].x);
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p1Out.y = p1s[0].y + lambda * (p1s[2].y - p1s[0].y);
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//*p2Out = p2s[0] + lambda * (p2s[2] - p2s[0]);
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p2Out.x = p2s[0].x + lambda * (p2s[2].x - p2s[0].x);
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p2Out.y = p2s[0].y + lambda * (p2s[2].y - p2s[0].y);
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//p1s[1] = p1s[2];
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p1s[1].SetV(p1s[2]);
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//p2s[1] = p2s[2];
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p2s[1].SetV(p2s[2]);
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//points[1] = points[2];
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points[1].SetV(points[2]);
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return 2;
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}
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// Inside the triangle, compute barycentric coordinates
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//float32 denom = va + vb + vc;
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var denom = va + vb + vc;
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//b2Settings.b2Assert(denom > 0.0);
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denom = 1.0 / denom;
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//float32 u = va * denom;
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var u = va * denom;
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//float32 v = vb * denom;
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var v = vb * denom;
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//float32 w = 1.0f - u - v;
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var w = 1.0 - u - v;
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//*p1Out = u * p1s[0] + v * p1s[1] + w * p1s[2];
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p1Out.x = u * p1s[0].x + v * p1s[1].x + w * p1s[2].x;
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p1Out.y = u * p1s[0].y + v * p1s[1].y + w * p1s[2].y;
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//*p2Out = u * p2s[0] + v * p2s[1] + w * p2s[2];
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p2Out.x = u * p2s[0].x + v * p2s[1].x + w * p2s[2].x;
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p2Out.y = u * p2s[0].y + v * p2s[1].y + w * p2s[2].y;
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return 3;
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};
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b2Distance.InPoinsts = function(w, points, pointCount)
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{
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for (var i = 0; i < pointCount; ++i)
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{
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if (w.x == points[i].x && w.y == points[i].y)
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{
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return true;
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}
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}
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return false;
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};
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b2Distance.Distance = function(p1Out, p2Out, shape1, shape2)
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{
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//b2Vec2 p1s[3], p2s[3];
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var p1s = new Array(3);
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var p2s = new Array(3);
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//b2Vec2 points[3];
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var points = new Array(3);
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//int32 pointCount = 0;
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var pointCount = 0;
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//*p1Out = shape1->m_position;
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p1Out.SetV(shape1.m_position);
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//*p2Out = shape2->m_position;
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p2Out.SetV(shape2.m_position);
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var vSqr = 0.0;
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var maxIterations = 20;
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for (var iter = 0; iter < maxIterations; ++iter)
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{
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//b2Vec2 v = *p2Out - *p1Out;
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var vX = p2Out.x - p1Out.x;
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var vY = p2Out.y - p1Out.y;
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//b2Vec2 w1 = shape1->Support(v);
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var w1 = shape1.Support(vX, vY);
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//b2Vec2 w2 = shape2->Support(-v);
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var w2 = shape2.Support(-vX, -vY);
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//float32 vSqr = b2Dot(v, v);
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vSqr = (vX*vX + vY*vY);
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//b2Vec2 w = w2 - w1;
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var wX = w2.x - w1.x;
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var wY = w2.y - w1.y;
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//float32 vw = b2Dot(v, w);
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var vw = (vX*wX + vY*wY);
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//if (vSqr - b2Dot(v, w) <= 0.01f * vSqr)
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if (vSqr - b2Dot(vX * wX + vY * wY) <= 0.01 * vSqr)
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{
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if (pointCount == 0)
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{
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//*p1Out = w1;
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p1Out.SetV(w1);
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//*p2Out = w2;
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p2Out.SetV(w2);
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}
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b2Distance.g_GJK_Iterations = iter;
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return Math.sqrt(vSqr);
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}
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switch (pointCount)
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{
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case 0:
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//p1s[0] = w1;
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p1s[0].SetV(w1);
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//p2s[0] = w2;
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p2s[0].SetV(w2);
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points[0] = w;
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//*p1Out = p1s[0];
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p1Out.SetV(p1s[0]);
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//*p2Out = p2s[0];
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p2Out.SetV(p2s[0]);
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++pointCount;
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break;
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case 1:
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//p1s[1] = w1;
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p1s[1].SetV(w1);
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//p2s[1] = w2;
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p2s[1].SetV(w2);
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//points[1] = w;
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points[1].x = wX;
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points[1].y = wY;
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pointCount = b2Distance.ProcessTwo(p1Out, p2Out, p1s, p2s, points);
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break;
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case 2:
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//p1s[2] = w1;
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p1s[2].SetV(w1);
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//p2s[2] = w2;
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p2s[2].SetV(w2);
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//points[2] = w;
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points[2].x = wX;
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points[2].y = wY;
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pointCount = b2Distance.ProcessThree(p1Out, p2Out, p1s, p2s, points);
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break;
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}
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// If we have three points, then the origin is in the corresponding triangle.
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if (pointCount == 3)
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{
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b2Distance.g_GJK_Iterations = iter;
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return 0.0;
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}
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//float32 maxSqr = -FLT_MAX;
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var maxSqr = -Number.MAX_VALUE;
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for (var i = 0; i < pointCount; ++i)
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{
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//maxSqr = b2Math.b2Max(maxSqr, b2Dot(points[i], points[i]));
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maxSqr = b2Math.b2Max(maxSqr, (points[i].x*points[i].x + points[i].y*points[i].y));
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}
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if (pointCount == 3 || vSqr <= 100.0 * Number.MIN_VALUE * maxSqr)
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{
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b2Distance.g_GJK_Iterations = iter;
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return Math.sqrt(vSqr);
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}
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}
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b2Distance.g_GJK_Iterations = maxIterations;
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return Math.sqrt(vSqr);
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};
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b2Distance.g_GJK_Iterations = 0;
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