去掉obi，使用自写绳索

Assets/Obi/Scripts/Common/Backends/Burst/Solver/UpdateVelocitiesJob.cs

@@ -1,58 +0,0 @@
-#if (OBI_BURST && OBI_MATHEMATICS && OBI_COLLECTIONS)
-using UnityEngine;
-using Unity.Jobs;
-using Unity.Collections;
-using Unity.Mathematics;
-using Unity.Burst;
-using System;
-using System.Collections;
-
-namespace Obi
-{
-    [BurstCompile]
-    struct UpdateVelocitiesJob : IJobParallelFor
-    {
-        [ReadOnly] public NativeArray<int> activeParticles;
-
-        // linear/position properties:
-        [ReadOnly] public NativeArray<float> inverseMasses;
-        [ReadOnly] public NativeArray<float4> previousPositions;
-        [NativeDisableParallelForRestriction] public NativeArray<float4> positions;
-        [NativeDisableParallelForRestriction] [WriteOnly] public NativeArray<float4> velocities;
-
-        // angular/orientation properties:
-        [ReadOnly] public NativeArray<float> inverseRotationalMasses;
-        [ReadOnly] public NativeArray<quaternion> previousOrientations;
-        [NativeDisableParallelForRestriction] public NativeArray<quaternion> orientations;
-        [NativeDisableParallelForRestriction] public NativeArray<float4> angularVelocities;
-
-        [ReadOnly] public float deltaTime;
-        [ReadOnly] public bool is2D;
-
-        // The code actually running on the job
-        public void Execute(int index)
-        {
-            int i = activeParticles[index];
-
-            // Project particles on the XY plane if we are in 2D mode:
-            if (is2D)
-            {
-                // restrict position to the 2D plane
-                float4 pos = positions[i];
-                pos[2] = previousPositions[i][2];
-                positions[i] = pos;
-            }
-
-            if (inverseMasses[i] > 0)
-                velocities[i] = BurstIntegration.DifferentiateLinear(positions[i], previousPositions[i], deltaTime);
-            else
-                velocities[i] = float4.zero;
-
-            if (inverseRotationalMasses[i] > 0)
-                angularVelocities[i] = new float4(BurstIntegration.DifferentiateAngular(orientations[i], previousOrientations[i], deltaTime).xyz, angularVelocities[i].w);
-            else
-                angularVelocities[i] = float4.zero;
-        }
-    }
-}
-#endif