780 lines
25 KiB
C#
780 lines
25 KiB
C#
/*
|
|
* Farseer Physics Engine based on Box2D.XNA port:
|
|
* Copyright (c) 2010 Ian Qvist
|
|
*
|
|
* Box2D.XNA port of Box2D:
|
|
* Copyright (c) 2009 Brandon Furtwangler, Nathan Furtwangler
|
|
*
|
|
* Original source Box2D:
|
|
* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
|
|
*
|
|
* 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 as such, and must not be
|
|
* misrepresented as being the original software.
|
|
* 3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
|
|
using System;
|
|
using System.Diagnostics;
|
|
using FarseerPhysics.Collision.Shapes;
|
|
using FarseerPhysics.Common;
|
|
using Microsoft.Xna.Framework;
|
|
|
|
namespace FarseerPhysics.Collision
|
|
{
|
|
/// <summary>
|
|
/// A distance proxy is used by the GJK algorithm.
|
|
/// It encapsulates any shape.
|
|
/// </summary>
|
|
public class DistanceProxy
|
|
{
|
|
internal float Radius;
|
|
internal Vertices Vertices = new Vertices();
|
|
|
|
/// <summary>
|
|
/// Initialize the proxy using the given shape. The shape
|
|
/// must remain in scope while the proxy is in use.
|
|
/// </summary>
|
|
/// <param name="shape">The shape.</param>
|
|
/// <param name="index">The index.</param>
|
|
public void Set(Shape shape, int index)
|
|
{
|
|
switch (shape.ShapeType)
|
|
{
|
|
case ShapeType.Circle:
|
|
{
|
|
CircleShape circle = (CircleShape)shape;
|
|
Vertices.Clear();
|
|
Vertices.Add(circle.Position);
|
|
Radius = circle.Radius;
|
|
}
|
|
break;
|
|
|
|
case ShapeType.Polygon:
|
|
{
|
|
PolygonShape polygon = (PolygonShape)shape;
|
|
Vertices.Clear();
|
|
for (int i = 0; i < polygon.Vertices.Count; i++)
|
|
{
|
|
Vertices.Add(polygon.Vertices[i]);
|
|
}
|
|
Radius = polygon.Radius;
|
|
}
|
|
break;
|
|
|
|
case ShapeType.Loop:
|
|
{
|
|
LoopShape loop = (LoopShape)shape;
|
|
Debug.Assert(0 <= index && index < loop.Vertices.Count);
|
|
Vertices.Clear();
|
|
Vertices.Add(loop.Vertices[index]);
|
|
Vertices.Add(index + 1 < loop.Vertices.Count ? loop.Vertices[index + 1] : loop.Vertices[0]);
|
|
|
|
Radius = loop.Radius;
|
|
}
|
|
break;
|
|
|
|
case ShapeType.Edge:
|
|
{
|
|
EdgeShape edge = (EdgeShape)shape;
|
|
Vertices.Clear();
|
|
Vertices.Add(edge.Vertex1);
|
|
Vertices.Add(edge.Vertex2);
|
|
Radius = edge.Radius;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
Debug.Assert(false);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Get the supporting vertex index in the given direction.
|
|
/// </summary>
|
|
/// <param name="direction">The direction.</param>
|
|
/// <returns></returns>
|
|
public int GetSupport(Vector2 direction)
|
|
{
|
|
int bestIndex = 0;
|
|
float bestValue = Vector2.Dot(Vertices[0], direction);
|
|
for (int i = 1; i < Vertices.Count; ++i)
|
|
{
|
|
float value = Vector2.Dot(Vertices[i], direction);
|
|
if (value > bestValue)
|
|
{
|
|
bestIndex = i;
|
|
bestValue = value;
|
|
}
|
|
}
|
|
|
|
return bestIndex;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Get the supporting vertex in the given direction.
|
|
/// </summary>
|
|
/// <param name="direction">The direction.</param>
|
|
/// <returns></returns>
|
|
public Vector2 GetSupportVertex(Vector2 direction)
|
|
{
|
|
int bestIndex = 0;
|
|
float bestValue = Vector2.Dot(Vertices[0], direction);
|
|
for (int i = 1; i < Vertices.Count; ++i)
|
|
{
|
|
float value = Vector2.Dot(Vertices[i], direction);
|
|
if (value > bestValue)
|
|
{
|
|
bestIndex = i;
|
|
bestValue = value;
|
|
}
|
|
}
|
|
|
|
return Vertices[bestIndex];
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Used to warm start ComputeDistance.
|
|
/// Set count to zero on first call.
|
|
/// </summary>
|
|
public struct SimplexCache
|
|
{
|
|
/// <summary>
|
|
/// Length or area
|
|
/// </summary>
|
|
public ushort Count;
|
|
|
|
/// <summary>
|
|
/// Vertices on shape A
|
|
/// </summary>
|
|
public FixedArray3<byte> IndexA;
|
|
|
|
/// <summary>
|
|
/// Vertices on shape B
|
|
/// </summary>
|
|
public FixedArray3<byte> IndexB;
|
|
|
|
public float Metric;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Input for ComputeDistance.
|
|
/// You have to option to use the shape radii
|
|
/// in the computation.
|
|
/// </summary>
|
|
public class DistanceInput
|
|
{
|
|
public DistanceProxy ProxyA = new DistanceProxy();
|
|
public DistanceProxy ProxyB = new DistanceProxy();
|
|
public Transform TransformA;
|
|
public Transform TransformB;
|
|
public bool UseRadii;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Output for ComputeDistance.
|
|
/// </summary>
|
|
public struct DistanceOutput
|
|
{
|
|
public float Distance;
|
|
|
|
/// <summary>
|
|
/// Number of GJK iterations used
|
|
/// </summary>
|
|
public int Iterations;
|
|
|
|
/// <summary>
|
|
/// Closest point on shapeA
|
|
/// </summary>
|
|
public Vector2 PointA;
|
|
|
|
/// <summary>
|
|
/// Closest point on shapeB
|
|
/// </summary>
|
|
public Vector2 PointB;
|
|
}
|
|
|
|
internal struct SimplexVertex
|
|
{
|
|
/// <summary>
|
|
/// Barycentric coordinate for closest point
|
|
/// </summary>
|
|
public float A;
|
|
|
|
/// <summary>
|
|
/// wA index
|
|
/// </summary>
|
|
public int IndexA;
|
|
|
|
/// <summary>
|
|
/// wB index
|
|
/// </summary>
|
|
public int IndexB;
|
|
|
|
/// <summary>
|
|
/// wB - wA
|
|
/// </summary>
|
|
public Vector2 W;
|
|
|
|
/// <summary>
|
|
/// Support point in proxyA
|
|
/// </summary>
|
|
public Vector2 WA;
|
|
|
|
/// <summary>
|
|
/// Support point in proxyB
|
|
/// </summary>
|
|
public Vector2 WB;
|
|
}
|
|
|
|
internal struct Simplex
|
|
{
|
|
internal int Count;
|
|
internal FixedArray3<SimplexVertex> V;
|
|
|
|
internal void ReadCache(ref SimplexCache cache,
|
|
DistanceProxy proxyA, ref Transform transformA,
|
|
DistanceProxy proxyB, ref Transform transformB)
|
|
{
|
|
Debug.Assert(cache.Count <= 3);
|
|
|
|
// Copy data from cache.
|
|
Count = cache.Count;
|
|
for (int i = 0; i < Count; ++i)
|
|
{
|
|
SimplexVertex v = V[i];
|
|
v.IndexA = cache.IndexA[i];
|
|
v.IndexB = cache.IndexB[i];
|
|
Vector2 wALocal = proxyA.Vertices[v.IndexA];
|
|
Vector2 wBLocal = proxyB.Vertices[v.IndexB];
|
|
v.WA = MathUtils.Multiply(ref transformA, wALocal);
|
|
v.WB = MathUtils.Multiply(ref transformB, wBLocal);
|
|
v.W = v.WB - v.WA;
|
|
v.A = 0.0f;
|
|
V[i] = v;
|
|
}
|
|
|
|
// Compute the new simplex metric, if it is substantially different than
|
|
// old metric then flush the simplex.
|
|
if (Count > 1)
|
|
{
|
|
float metric1 = cache.Metric;
|
|
float metric2 = GetMetric();
|
|
if (metric2 < 0.5f * metric1 || 2.0f * metric1 < metric2 || metric2 < Settings.Epsilon)
|
|
{
|
|
// Reset the simplex.
|
|
Count = 0;
|
|
}
|
|
}
|
|
|
|
// If the cache is empty or invalid ...
|
|
if (Count == 0)
|
|
{
|
|
SimplexVertex v = V[0];
|
|
v.IndexA = 0;
|
|
v.IndexB = 0;
|
|
Vector2 wALocal = proxyA.Vertices[0];
|
|
Vector2 wBLocal = proxyB.Vertices[0];
|
|
v.WA = MathUtils.Multiply(ref transformA, wALocal);
|
|
v.WB = MathUtils.Multiply(ref transformB, wBLocal);
|
|
v.W = v.WB - v.WA;
|
|
V[0] = v;
|
|
Count = 1;
|
|
}
|
|
}
|
|
|
|
internal void WriteCache(ref SimplexCache cache)
|
|
{
|
|
cache.Metric = GetMetric();
|
|
cache.Count = (UInt16)Count;
|
|
for (int i = 0; i < Count; ++i)
|
|
{
|
|
cache.IndexA[i] = (byte)(V[i].IndexA);
|
|
cache.IndexB[i] = (byte)(V[i].IndexB);
|
|
}
|
|
}
|
|
|
|
internal Vector2 GetSearchDirection()
|
|
{
|
|
switch (Count)
|
|
{
|
|
case 1:
|
|
return -V[0].W;
|
|
|
|
case 2:
|
|
{
|
|
Vector2 e12 = V[1].W - V[0].W;
|
|
float sgn = MathUtils.Cross(e12, -V[0].W);
|
|
if (sgn > 0.0f)
|
|
{
|
|
// Origin is left of e12.
|
|
return new Vector2(-e12.Y, e12.X);
|
|
}
|
|
else
|
|
{
|
|
// Origin is right of e12.
|
|
return new Vector2(e12.Y, -e12.X);
|
|
}
|
|
}
|
|
|
|
default:
|
|
Debug.Assert(false);
|
|
return Vector2.Zero;
|
|
}
|
|
}
|
|
|
|
internal Vector2 GetClosestPoint()
|
|
{
|
|
switch (Count)
|
|
{
|
|
case 0:
|
|
Debug.Assert(false);
|
|
return Vector2.Zero;
|
|
|
|
case 1:
|
|
return V[0].W;
|
|
|
|
case 2:
|
|
return V[0].A * V[0].W + V[1].A * V[1].W;
|
|
|
|
case 3:
|
|
return Vector2.Zero;
|
|
|
|
default:
|
|
Debug.Assert(false);
|
|
return Vector2.Zero;
|
|
}
|
|
}
|
|
|
|
internal void GetWitnessPoints(out Vector2 pA, out Vector2 pB)
|
|
{
|
|
switch (Count)
|
|
{
|
|
case 0:
|
|
pA = Vector2.Zero;
|
|
pB = Vector2.Zero;
|
|
Debug.Assert(false);
|
|
break;
|
|
|
|
case 1:
|
|
pA = V[0].WA;
|
|
pB = V[0].WB;
|
|
break;
|
|
|
|
case 2:
|
|
pA = V[0].A * V[0].WA + V[1].A * V[1].WA;
|
|
pB = V[0].A * V[0].WB + V[1].A * V[1].WB;
|
|
break;
|
|
|
|
case 3:
|
|
pA = V[0].A * V[0].WA + V[1].A * V[1].WA + V[2].A * V[2].WA;
|
|
pB = pA;
|
|
break;
|
|
|
|
default:
|
|
throw new Exception();
|
|
}
|
|
}
|
|
|
|
internal float GetMetric()
|
|
{
|
|
switch (Count)
|
|
{
|
|
case 0:
|
|
Debug.Assert(false);
|
|
return 0.0f;
|
|
|
|
case 1:
|
|
return 0.0f;
|
|
|
|
case 2:
|
|
return (V[0].W - V[1].W).Length();
|
|
|
|
case 3:
|
|
return MathUtils.Cross(V[1].W - V[0].W, V[2].W - V[0].W);
|
|
|
|
default:
|
|
Debug.Assert(false);
|
|
return 0.0f;
|
|
}
|
|
}
|
|
|
|
// Solve a line segment using barycentric coordinates.
|
|
//
|
|
// p = a1 * w1 + a2 * w2
|
|
// a1 + a2 = 1
|
|
//
|
|
// The vector from the origin to the closest point on the line is
|
|
// perpendicular to the line.
|
|
// e12 = w2 - w1
|
|
// dot(p, e) = 0
|
|
// a1 * dot(w1, e) + a2 * dot(w2, e) = 0
|
|
//
|
|
// 2-by-2 linear system
|
|
// [1 1 ][a1] = [1]
|
|
// [w1.e12 w2.e12][a2] = [0]
|
|
//
|
|
// Define
|
|
// d12_1 = dot(w2, e12)
|
|
// d12_2 = -dot(w1, e12)
|
|
// d12 = d12_1 + d12_2
|
|
//
|
|
// Solution
|
|
// a1 = d12_1 / d12
|
|
// a2 = d12_2 / d12
|
|
|
|
internal void Solve2()
|
|
{
|
|
Vector2 w1 = V[0].W;
|
|
Vector2 w2 = V[1].W;
|
|
Vector2 e12 = w2 - w1;
|
|
|
|
// w1 region
|
|
float d12_2 = -Vector2.Dot(w1, e12);
|
|
if (d12_2 <= 0.0f)
|
|
{
|
|
// a2 <= 0, so we clamp it to 0
|
|
SimplexVertex v0 = V[0];
|
|
v0.A = 1.0f;
|
|
V[0] = v0;
|
|
Count = 1;
|
|
return;
|
|
}
|
|
|
|
// w2 region
|
|
float d12_1 = Vector2.Dot(w2, e12);
|
|
if (d12_1 <= 0.0f)
|
|
{
|
|
// a1 <= 0, so we clamp it to 0
|
|
SimplexVertex v1 = V[1];
|
|
v1.A = 1.0f;
|
|
V[1] = v1;
|
|
Count = 1;
|
|
V[0] = V[1];
|
|
return;
|
|
}
|
|
|
|
// Must be in e12 region.
|
|
float inv_d12 = 1.0f / (d12_1 + d12_2);
|
|
SimplexVertex v0_2 = V[0];
|
|
SimplexVertex v1_2 = V[1];
|
|
v0_2.A = d12_1 * inv_d12;
|
|
v1_2.A = d12_2 * inv_d12;
|
|
V[0] = v0_2;
|
|
V[1] = v1_2;
|
|
Count = 2;
|
|
}
|
|
|
|
// Possible regions:
|
|
// - points[2]
|
|
// - edge points[0]-points[2]
|
|
// - edge points[1]-points[2]
|
|
// - inside the triangle
|
|
internal void Solve3()
|
|
{
|
|
Vector2 w1 = V[0].W;
|
|
Vector2 w2 = V[1].W;
|
|
Vector2 w3 = V[2].W;
|
|
|
|
// Edge12
|
|
// [1 1 ][a1] = [1]
|
|
// [w1.e12 w2.e12][a2] = [0]
|
|
// a3 = 0
|
|
Vector2 e12 = w2 - w1;
|
|
float w1e12 = Vector2.Dot(w1, e12);
|
|
float w2e12 = Vector2.Dot(w2, e12);
|
|
float d12_1 = w2e12;
|
|
float d12_2 = -w1e12;
|
|
|
|
// Edge13
|
|
// [1 1 ][a1] = [1]
|
|
// [w1.e13 w3.e13][a3] = [0]
|
|
// a2 = 0
|
|
Vector2 e13 = w3 - w1;
|
|
float w1e13 = Vector2.Dot(w1, e13);
|
|
float w3e13 = Vector2.Dot(w3, e13);
|
|
float d13_1 = w3e13;
|
|
float d13_2 = -w1e13;
|
|
|
|
// Edge23
|
|
// [1 1 ][a2] = [1]
|
|
// [w2.e23 w3.e23][a3] = [0]
|
|
// a1 = 0
|
|
Vector2 e23 = w3 - w2;
|
|
float w2e23 = Vector2.Dot(w2, e23);
|
|
float w3e23 = Vector2.Dot(w3, e23);
|
|
float d23_1 = w3e23;
|
|
float d23_2 = -w2e23;
|
|
|
|
// Triangle123
|
|
float n123 = MathUtils.Cross(e12, e13);
|
|
|
|
float d123_1 = n123 * MathUtils.Cross(w2, w3);
|
|
float d123_2 = n123 * MathUtils.Cross(w3, w1);
|
|
float d123_3 = n123 * MathUtils.Cross(w1, w2);
|
|
|
|
// w1 region
|
|
if (d12_2 <= 0.0f && d13_2 <= 0.0f)
|
|
{
|
|
SimplexVertex v0_1 = V[0];
|
|
v0_1.A = 1.0f;
|
|
V[0] = v0_1;
|
|
Count = 1;
|
|
return;
|
|
}
|
|
|
|
// e12
|
|
if (d12_1 > 0.0f && d12_2 > 0.0f && d123_3 <= 0.0f)
|
|
{
|
|
float inv_d12 = 1.0f / (d12_1 + d12_2);
|
|
SimplexVertex v0_2 = V[0];
|
|
SimplexVertex v1_2 = V[1];
|
|
v0_2.A = d12_1 * inv_d12;
|
|
v1_2.A = d12_2 * inv_d12;
|
|
V[0] = v0_2;
|
|
V[1] = v1_2;
|
|
Count = 2;
|
|
return;
|
|
}
|
|
|
|
// e13
|
|
if (d13_1 > 0.0f && d13_2 > 0.0f && d123_2 <= 0.0f)
|
|
{
|
|
float inv_d13 = 1.0f / (d13_1 + d13_2);
|
|
SimplexVertex v0_3 = V[0];
|
|
SimplexVertex v2_3 = V[2];
|
|
v0_3.A = d13_1 * inv_d13;
|
|
v2_3.A = d13_2 * inv_d13;
|
|
V[0] = v0_3;
|
|
V[2] = v2_3;
|
|
Count = 2;
|
|
V[1] = V[2];
|
|
return;
|
|
}
|
|
|
|
// w2 region
|
|
if (d12_1 <= 0.0f && d23_2 <= 0.0f)
|
|
{
|
|
SimplexVertex v1_4 = V[1];
|
|
v1_4.A = 1.0f;
|
|
V[1] = v1_4;
|
|
Count = 1;
|
|
V[0] = V[1];
|
|
return;
|
|
}
|
|
|
|
// w3 region
|
|
if (d13_1 <= 0.0f && d23_1 <= 0.0f)
|
|
{
|
|
SimplexVertex v2_5 = V[2];
|
|
v2_5.A = 1.0f;
|
|
V[2] = v2_5;
|
|
Count = 1;
|
|
V[0] = V[2];
|
|
return;
|
|
}
|
|
|
|
// e23
|
|
if (d23_1 > 0.0f && d23_2 > 0.0f && d123_1 <= 0.0f)
|
|
{
|
|
float inv_d23 = 1.0f / (d23_1 + d23_2);
|
|
SimplexVertex v1_6 = V[1];
|
|
SimplexVertex v2_6 = V[2];
|
|
v1_6.A = d23_1 * inv_d23;
|
|
v2_6.A = d23_2 * inv_d23;
|
|
V[1] = v1_6;
|
|
V[2] = v2_6;
|
|
Count = 2;
|
|
V[0] = V[2];
|
|
return;
|
|
}
|
|
|
|
// Must be in triangle123
|
|
float inv_d123 = 1.0f / (d123_1 + d123_2 + d123_3);
|
|
SimplexVertex v0_7 = V[0];
|
|
SimplexVertex v1_7 = V[1];
|
|
SimplexVertex v2_7 = V[2];
|
|
v0_7.A = d123_1 * inv_d123;
|
|
v1_7.A = d123_2 * inv_d123;
|
|
v2_7.A = d123_3 * inv_d123;
|
|
V[0] = v0_7;
|
|
V[1] = v1_7;
|
|
V[2] = v2_7;
|
|
Count = 3;
|
|
}
|
|
}
|
|
|
|
public static class Distance
|
|
{
|
|
public static int GJKCalls, GJKIters, GJKMaxIters;
|
|
|
|
public static void ComputeDistance(out DistanceOutput output,
|
|
out SimplexCache cache,
|
|
DistanceInput input)
|
|
{
|
|
cache = new SimplexCache();
|
|
++GJKCalls;
|
|
|
|
// Initialize the simplex.
|
|
Simplex simplex = new Simplex();
|
|
simplex.ReadCache(ref cache, input.ProxyA, ref input.TransformA, input.ProxyB, ref input.TransformB);
|
|
|
|
// Get simplex vertices as an array.
|
|
const int k_maxIters = 20;
|
|
|
|
// These store the vertices of the last simplex so that we
|
|
// can check for duplicates and prevent cycling.
|
|
FixedArray3<int> saveA = new FixedArray3<int>();
|
|
FixedArray3<int> saveB = new FixedArray3<int>();
|
|
|
|
Vector2 closestPoint = simplex.GetClosestPoint();
|
|
float distanceSqr1 = closestPoint.LengthSquared();
|
|
float distanceSqr2 = distanceSqr1;
|
|
|
|
// Main iteration loop.
|
|
int iter = 0;
|
|
while (iter < k_maxIters)
|
|
{
|
|
// Copy simplex so we can identify duplicates.
|
|
int saveCount = simplex.Count;
|
|
for (int i = 0; i < saveCount; ++i)
|
|
{
|
|
saveA[i] = simplex.V[i].IndexA;
|
|
saveB[i] = simplex.V[i].IndexB;
|
|
}
|
|
|
|
switch (simplex.Count)
|
|
{
|
|
case 1:
|
|
break;
|
|
|
|
case 2:
|
|
simplex.Solve2();
|
|
break;
|
|
|
|
case 3:
|
|
simplex.Solve3();
|
|
break;
|
|
|
|
default:
|
|
Debug.Assert(false);
|
|
break;
|
|
}
|
|
|
|
// If we have 3 points, then the origin is in the corresponding triangle.
|
|
if (simplex.Count == 3)
|
|
{
|
|
break;
|
|
}
|
|
|
|
// Compute closest point.
|
|
Vector2 p = simplex.GetClosestPoint();
|
|
distanceSqr2 = p.LengthSquared();
|
|
|
|
// Ensure progress
|
|
if (distanceSqr2 >= distanceSqr1)
|
|
{
|
|
//break;
|
|
}
|
|
distanceSqr1 = distanceSqr2;
|
|
|
|
// Get search direction.
|
|
Vector2 d = simplex.GetSearchDirection();
|
|
|
|
// Ensure the search direction is numerically fit.
|
|
if (d.LengthSquared() < Settings.Epsilon * Settings.Epsilon)
|
|
{
|
|
// The origin is probably contained by a line segment
|
|
// or triangle. Thus the shapes are overlapped.
|
|
|
|
// We can't return zero here even though there may be overlap.
|
|
// In case the simplex is a point, segment, or triangle it is difficult
|
|
// to determine if the origin is contained in the CSO or very close to it.
|
|
break;
|
|
}
|
|
|
|
// Compute a tentative new simplex vertex using support points.
|
|
SimplexVertex vertex = simplex.V[simplex.Count];
|
|
vertex.IndexA = input.ProxyA.GetSupport(MathUtils.MultiplyT(ref input.TransformA.R, -d));
|
|
vertex.WA = MathUtils.Multiply(ref input.TransformA, input.ProxyA.Vertices[vertex.IndexA]);
|
|
|
|
vertex.IndexB = input.ProxyB.GetSupport(MathUtils.MultiplyT(ref input.TransformB.R, d));
|
|
vertex.WB = MathUtils.Multiply(ref input.TransformB, input.ProxyB.Vertices[vertex.IndexB]);
|
|
vertex.W = vertex.WB - vertex.WA;
|
|
simplex.V[simplex.Count] = vertex;
|
|
|
|
// Iteration count is equated to the number of support point calls.
|
|
++iter;
|
|
++GJKIters;
|
|
|
|
// Check for duplicate support points. This is the main termination criteria.
|
|
bool duplicate = false;
|
|
for (int i = 0; i < saveCount; ++i)
|
|
{
|
|
if (vertex.IndexA == saveA[i] && vertex.IndexB == saveB[i])
|
|
{
|
|
duplicate = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If we found a duplicate support point we must exit to avoid cycling.
|
|
if (duplicate)
|
|
{
|
|
break;
|
|
}
|
|
|
|
// New vertex is ok and needed.
|
|
++simplex.Count;
|
|
}
|
|
|
|
GJKMaxIters = Math.Max(GJKMaxIters, iter);
|
|
|
|
// Prepare output.
|
|
simplex.GetWitnessPoints(out output.PointA, out output.PointB);
|
|
output.Distance = (output.PointA - output.PointB).Length();
|
|
output.Iterations = iter;
|
|
|
|
// Cache the simplex.
|
|
simplex.WriteCache(ref cache);
|
|
|
|
// Apply radii if requested.
|
|
if (input.UseRadii)
|
|
{
|
|
float rA = input.ProxyA.Radius;
|
|
float rB = input.ProxyB.Radius;
|
|
|
|
if (output.Distance > rA + rB && output.Distance > Settings.Epsilon)
|
|
{
|
|
// Shapes are still no overlapped.
|
|
// Move the witness points to the outer surface.
|
|
output.Distance -= rA + rB;
|
|
Vector2 normal = output.PointB - output.PointA;
|
|
normal.Normalize();
|
|
output.PointA += rA * normal;
|
|
output.PointB -= rB * normal;
|
|
}
|
|
else
|
|
{
|
|
// Shapes are overlapped when radii are considered.
|
|
// Move the witness points to the middle.
|
|
Vector2 p = 0.5f * (output.PointA + output.PointB);
|
|
output.PointA = p;
|
|
output.PointB = p;
|
|
output.Distance = 0.0f;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
} |