Exemple #1
0
        /**
         * Generates the particle based physical representation of the rope. This is the initialization method for the rope object
         * and should not be called directly once the object has been created.
         */
        protected override IEnumerator Initialize()
        {
            initialized           = false;
            initializing          = true;
            interParticleDistance = -1;

            RemoveFromSolver(null);

            if (ropePath == null)
            {
                Debug.LogError("Cannot initialize rope. There's no ropePath present. Please provide a spline to define the shape of the rope");
                yield break;
            }

            ropePath.RecalculateSplineLenght(0.00001f, 7);
            closed     = ropePath.closed;
            restLength = ropePath.Length;

            usedParticles  = Mathf.CeilToInt(restLength / thickness * resolution) + (closed ? 0:1);
            totalParticles = usedParticles;

            active              = new bool[totalParticles];
            positions           = new Vector3[totalParticles];
            orientations        = new Quaternion[totalParticles];
            velocities          = new Vector3[totalParticles];
            angularVelocities   = new Vector3[totalParticles];
            invMasses           = new float[totalParticles];
            invRotationalMasses = new float[totalParticles];
            principalRadii      = new Vector3[totalParticles];
            phases              = new int[totalParticles];
            restPositions       = new Vector4[totalParticles];
            restOrientations    = new Quaternion[totalParticles];
            colors              = new Color[totalParticles];

            int numSegments = usedParticles - (closed ? 0:1);

            if (numSegments > 0)
            {
                interParticleDistance = restLength / (float)numSegments;
            }
            else
            {
                interParticleDistance = 0;
            }

            float radius = interParticleDistance * resolution;

            for (int i = 0; i < usedParticles; i++)
            {
                active[i]              = true;
                invMasses[i]           = 1.0f / DEFAULT_PARTICLE_MASS;
                invRotationalMasses[i] = 1.0f / DEFAULT_PARTICLE_ROTATIONAL_MASS;
                float mu = ropePath.GetMuAtLenght(interParticleDistance * i);
                positions[i]      = transform.InverseTransformPoint(ropePath.transform.TransformPoint(ropePath.GetPositionAt(mu)));
                principalRadii[i] = Vector3.one * radius;
                phases[i]         = Oni.MakePhase(1, selfCollisions?Oni.ParticlePhase.SelfCollide:0);
                colors[i]         = Color.white;

                if (i % 100 == 0)
                {
                    yield return(new CoroutineJob.ProgressInfo("ObiRod: generating particles...", i / (float)usedParticles));
                }
            }

            StretchShearConstraints.Clear();
            ObiStretchShearConstraintBatch stretchBatch = new ObiStretchShearConstraintBatch(false, false, MIN_YOUNG_MODULUS, MAX_YOUNG_MODULUS);

            StretchShearConstraints.AddBatch(stretchBatch);

            // rotation minimizing frame:
            ObiCurveFrame frame = new ObiCurveFrame();

            frame.Reset();

            for (int i = 0; i < numSegments; i++)
            {
                int next = (i + 1) % (ropePath.closed ? usedParticles:usedParticles + 1);

                float   mu     = ropePath.GetMuAtLenght(interParticleDistance * i);
                Vector3 normal = transform.InverseTransformVector(ropePath.transform.TransformVector(ropePath.GetNormalAt(mu)));

                frame.Transport(positions[i], (positions[next] - positions[i]).normalized, 0);

                orientations[i]     = Quaternion.LookRotation(frame.tangent, normal);
                restOrientations[i] = orientations[i];

                // Also set the orientation of the next particle. If it is not the last one, we will overwrite it.
                // This makes sure that open rods provide an orientation for their last particle (or rather, a phantom segment past the last particle).

                orientations[next]     = orientations[i];
                restOrientations[next] = orientations[i];

                stretchBatch.AddConstraint(i, next, interParticleDistance, Quaternion.identity, Vector3.one);

                if (i % 500 == 0)
                {
                    yield return(new CoroutineJob.ProgressInfo("ObiRod: generating structural constraints...", i / (float)numSegments));
                }
            }

            BendTwistConstraints.Clear();
            ObiBendTwistConstraintBatch twistBatch = new ObiBendTwistConstraintBatch(false, false, MIN_YOUNG_MODULUS, MAX_YOUNG_MODULUS);

            BendTwistConstraints.AddBatch(twistBatch);

            // the last bend constraint couples the last segment and a phantom segment past the last particle.
            for (int i = 0; i < numSegments; i++)
            {
                int next = (i + 1) % (ropePath.closed ? usedParticles:usedParticles + 1);

                Quaternion darboux = keepInitialShape ? ObiUtils.RestDarboux(orientations[i], orientations[next]) : Quaternion.identity;
                twistBatch.AddConstraint(i, next, darboux, Vector3.one);

                if (i % 500 == 0)
                {
                    yield return(new CoroutineJob.ProgressInfo("ObiRod: generating structural constraints...", i / (float)numSegments));
                }
            }

            ChainConstraints.Clear();
            ObiChainConstraintBatch chainBatch = new ObiChainConstraintBatch(false, false, MIN_YOUNG_MODULUS, MAX_YOUNG_MODULUS);

            ChainConstraints.AddBatch(chainBatch);

            int[] indices = new int[usedParticles + (closed ? 1:0)];

            for (int i = 0; i < usedParticles; ++i)
            {
                indices[i] = i;
            }

            // Add the first particle as the last index of the chain, if closed.
            if (closed)
            {
                indices[usedParticles] = 0;
            }

            chainBatch.AddConstraint(indices, interParticleDistance, 1, 1);


            // Initialize tether constraints:
            TetherConstraints.Clear();

            // Initialize pin constraints:
            PinConstraints.Clear();
            ObiPinConstraintBatch pinBatch = new ObiPinConstraintBatch(false, false, MIN_YOUNG_MODULUS, MAX_YOUNG_MODULUS);

            PinConstraints.AddBatch(pinBatch);

            initializing = false;
            initialized  = true;

            RegenerateRestPositions();
        }