(17-02-2020, 07:36 AM)GrimCaplan Wrote: I'm attempting to put together a simple script based off ObiParticlePicker that supports multiple touches. The multiple touches is working fine. The issue I'm having is that when I select a particle index, I do not seem to understand how to modify the particle's position.

I'm attempting to add a value to the y-level of a renderable position in order to increase its height. I know the axis in which I need to affect depends on the rotation and position of the cloth.

I have also done some debugging and confirmed that an index is in-fact being selected.



The reason for this is because I don't really want the effect that the particle dragger produces. When moving the finger around the screen it attempts to hold on to that particle even if I swipe to the other side of the screen whereas my desired functionality is the elevation and/or depression of particles under the finger. I know I could simply adapt the OnParticleDragged and treat all movement as a sequence of OnParticlePicked and then OnParticleReleased, but my goal is not just functioning but actually increasing my understanding of the system. I'll probably be using it a lot in the future. Directly effecting the elevation also seems less 'hackish' than hooking the two events in series.

Also if it would be helpful you can use the multi-touch for the "courtesy" code because that does actually work. I promise I'm not a terrible developer, Obi has just been hard for me to absorb.

Code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Obi;

public class SlimeSolverManager : MonoBehaviour
{
   [SerializeField]
   ObiSolver m_Solver;

   [SerializeField]
   float m_TouchRadius;
   [SerializeField]
   float m_TouchDistortionLevel = 1;

   private int[] m_PickedParticleIndices;
   private float pickedParticleDepth = 0;

   private void OnEnable()
   {
       Debug.Assert(m_Solver != null, "Slime Solver Manager Missing Obi Solver Component Reference!");
   }

   // Update is called once per frame
   void LateUpdate()
   {
       if (m_Solver)
       {
           if (Input.touchCount > 0)
               m_PickedParticleIndices = new int[Input.touchCount];

           foreach (Touch touch in Input.touches)
           {
               m_PickedParticleIndices[touch.fingerId] = -1;

               Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);

               float closestMu = float.MaxValue;
               float closestDistance = float.MaxValue;

               // Find the closest particle hit by the ray:
               for (int i = 0; i < m_Solver.renderablePositions.count; ++i)
               {
                   float mu;
                   Vector3 projected = ObiUtils.ProjectPointLine
                       (m_Solver.renderablePositions[i], ray.origin, ray.origin + ray.direction, out mu, false);

                   float distanceToRay = Vector3.SqrMagnitude
                       ((Vector3)m_Solver.renderablePositions[i] - projected);

                   mu = Mathf.Max(0, mu);

                   float radius = m_Solver.principalRadii[i][0] * m_TouchRadius;

                   if (distanceToRay <= radius * radius && distanceToRay < closestDistance && mu < closestMu)
                   {
                       closestMu = mu;
                       closestDistance = distanceToRay;
                       m_PickedParticleIndices[touch.fingerId] = i;
                   }
               }

               if (m_PickedParticleIndices[touch.fingerId] >= 0)
               {
                   pickedParticleDepth = Camera.main.transform.InverseTransformVector((Vector3)m_Solver.renderablePositions
                       [m_PickedParticleIndices[touch.fingerId]] - Camera.main.transform.position).z;

                   Vector3 worldPosition = Camera.main.ScreenToWorldPoint
                           (new Vector3(Input.mousePosition.x, Input.mousePosition.y, pickedParticleDepth));

                   float x = m_Solver.renderablePositions[m_PickedParticleIndices[touch.fingerId]].x;
                   float y = m_Solver.renderablePositions[m_PickedParticleIndices[touch.fingerId]].y;
                   float z = m_Solver.renderablePositions[m_PickedParticleIndices[touch.fingerId]].z;
                   float w = m_Solver.renderablePositions[m_PickedParticleIndices[touch.fingerId]].w;

                   m_Solver.renderablePositions
                       [m_PickedParticleIndices[touch.fingerId]] =
                           new Vector4(x, y + m_TouchDistortionLevel, z, w);
               }

           }

       }
   }
}

I know the declaration of four floats is a little lazy but at this point I'm simply trying to get results. I'll opt later.

Quote:If the solver's interpolation mode is set to interpolate, solver.renderablePositions will contain temporally smoothed-out positions that won´t coincide with the actual particle positions at the end of the simulation step. That's why they are called "renderable": they are only used for smooth rendering, but they aren't needed by the solver and thus not calculated unless requested.

Quote:- Calculate a spring force that strives to keep each particle at y = 0. This is what will cause particles to fall back to their position when a touch ceases.

- When there's a touch present, calculate a force opposite to the previous one, that strives to keep the particle at y = some positive value.

(17-02-2020, 01:35 PM)GrimCaplan Wrote: Could you actually provide some code snippets on how to accomplish what you're describing? I'd appreciate it.

For instance: