Input for ComputeDistance. You have to option to use the shape radii in the computation.
        public static void ComputeDistance(out DistanceOutput output,
            out SimplexCache cache,
            ref DistanceInput input)
        {
            cache = new SimplexCache();
            ++GJKCalls;

            // Initialize the simplex.
            Simplex simplex = new Simplex();
            simplex.ReadCache(ref cache, ref input.ProxyA, ref input.TransformA, ref 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.GetVertex(vertex.IndexA));

                vertex.IndexB = input.ProxyB.GetSupport(MathUtils.MultiplyT(ref input.TransformB.R, d));
                vertex.WB = MathUtils.Multiply(ref input.TransformB, input.ProxyB.GetVertex(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;
                }
            }
        }
Example #2
0
        public static bool TestOverlap(Shape shapeA, int indexA,
                                       Shape shapeB, int indexB,
                                       ref Transform xfA, ref Transform xfB)
        {
            DistanceInput input = new DistanceInput();
            input.ProxyA.Set(shapeA, indexA);
            input.ProxyB.Set(shapeB, indexB);
            input.TransformA = xfA;
            input.TransformB = xfB;
            input.UseRadii = true;

            SimplexCache cache;
            DistanceOutput output;
            Distance.ComputeDistance(out output, out cache, ref input);

            return output.Distance < 10.0f*Settings.Epsilon;
        }