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RegenerateRestPositions strange code
#1
Exclamación 
Here original code from ObiRope
public override void RegenerateRestPositions(){

            var distanceBatch = DistanceConstraints.GetFirstBatch();
            if (distanceBatch.ConstraintCount > 0)
            {
                // Iterate trough all distance constraints in order:
                int particle = -1;
                int lastParticle = -1;
                float accumulatedDistance = 0;
                for (int i = 0; i < distanceBatch.ConstraintCount; ++i)
                {
                    if (i == 0)
                    {
                        lastParticle = particle = distanceBatch.springIndices[i * 2];
                        restPositions[particle] = new Vector4(0, 0, 0, 1);
                    }
                    accumulatedDistance += Mathf.Min(interParticleDistance, principalRadii[particle][0],principalRadii[lastParticle][0]);
                    particle = distanceBatch.springIndices[i * 2 + 1];
                    restPositions[particle] = Vector3.right * accumulatedDistance;
                    restPositions[particle][3] = 1; // activate rest position
                }
            }

            PushDataToSolver(ParticleData.REST_POSITIONS);
        }
First: this code generate (distanceBatch.ConstraintCount-1) float[3] arrays while Mathf.Min function, this makes unity garbage collector crazy.
Second: lastParticle  newer updated in cycle, this result in accumulatedDistance sum of distances from rope start to current point, not from previous to current point.
So finally accumulatedDistance  contains not total rope length but (distanceBatch.ConstraintCount-1)*ropeLength/2.
Are you sure that is right, because this is strange.
This is my implementation
public override void RegenerateRestPositions(){
            ObiDistanceConstraintBatch distanceBatch = DistanceConstraints.GetFirstBatch();
            if (distanceBatch.ConstraintCount > 0)
            {
                Vector3 right=Vector3.right;
                // Iterate trough all distance constraints in order:
                int lastParticle = distanceBatch.springIndices[0];
                float accumulatedDistance = 0;
                restPositions[0] = new Vector4(0, 0, 0, 1);
                for (int i = 0; i < distanceBatch.ConstraintCount; ++i)
                {
                    int particle = distanceBatch.springIndices[i * 2 + 1];
                    accumulatedDistance += Mathf.Min(interParticleDistance, Math.Min(principalRadii[particle][0],principalRadii[lastParticle][0]));
                    var ditanceoffset = right * accumulatedDistance;
                    restPositions[particle] =new Vector4(ditanceoffset.x,ditanceoffset.y,ditanceoffset.z,1);
                    lastParticle = particle;
                }
                PushDataToSolver(ParticleData.REST_POSITIONS);
            }
        }
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Messages In This Thread
RegenerateRestPositions strange code - by Teolog - 08-04-2019, 12:02 PM