Recolor Grass

Hey, I'm having some tough time adding grass to my game. I wanted each individual grass initial color to be the same as the ground's texture color at the exact spot. I managed doing it - making a grass particle system and changing ParticleSystem.Particle.color for each particle (don't know if its the most efficient way...).

The problem is that I want each individual grass particle (or maybe I'll be better off using detail mesh instead?) to change its color to red whenever a blood splatter decal touches it. Now, doing a loop through all the grass particles to determine w$$anonymous$$ch one is touc$$anonymous$$ng the decal is really going to cost performance.

Can you suggest any sufficient (or possible) way? (I'm guessing you could somehow do it using shaders and grass detail mesh, though I know not$$anonymous$$ng about them.)

Here's my current code:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 
 public class Grass_Particles_controller : MonoBehaviour {
 
 
     public float planeWidth;
     public float planeHeight;
     [Space(5)]
     public float rotationMin;
     public float rotationMax;
     [Space(5)] 
     public float strechMin;
     public float stretchMax;
     [Space(5)]
     public int grassAmount;
     [Space(10)]
     [Header("Texture")]
 
     public GameObject texturePlane;
 
 
     ParticleSystem ps;
 
 
     ParticleSystem.Particle[] grassList;
 
     bool toSetParticles = false;
 
 
     int texW,texH;
     Color32[] colorGrid;
 
     void Start()
     {
 
         gameObject.GetComponent<ParticleSystemRenderer>().pivot = new Vector3(0f,-0.5f,0f);
         ps = gameObject.GetComponent<ParticleSystem>();
 
         GetColorGrid();
         GenerateGrass();
 
 
     }
 
     void Update()
     {
         
 
         if(toSetParticles){ ps.SetParticles(grassList,grassAmount); toSetParticles=false;}
 
         }
 
 
 
     void GenerateGrass()
     {
         grassList = new ParticleSystem.Particle[grassAmount];
 
         ps.Clear();
 
         for(int i = 0; i<grassAmount; i++)
         {
             Vector3 gPosition =  new Vector3(Random.Range(-(planeWidth/2),planeWidth/2),0,Random.Range(-(planeHeight/2),planeHeight/2));
             grassList[i].size = Random.Range(strechMin,stretchMax);
             grassList[i].position = gPosition;
             grassList[i].rotation = Random.Range(rotationMin,rotationMax);
 
             Color32 newColor = GetPointColorFromPlane(gPosition);
             grassList[i].color = (Color)newColor;
 
         }
         toSetParticles = true;
 
     }
 
 
     void RecalculateColors()
     {
 
         ps.Clear();
 
         for(int i = 0; i<grassAmount; i++)
         {
             Color32 newColor = GetPointColorFromPlane(grassList[i].position);
             grassList[i].color = (Color)newColor;
 
         }
         toSetParticles = true;
     }
 
     void GetColorGrid()
     {
         Texture2D planeTexture = texturePlane.GetComponent<Renderer>().material.mainTexture as Texture2D;
         texW = planeTexture.width;
         texH = planeTexture.height;
         colorGrid =  planeTexture.GetPixels32();
     }
 
     Color32 GetPointColorFromPlane(Vector3 grassPosition)
     {
         RaycastHit[] $$anonymous$$ts;
         $$anonymous$$ts = Physics.RaycastAll(grassPosition+Vector3.up*0.001f,Vector3.down);
         Color32 target = Color.w$$anonymous$$te; 
         foreach (RaycastHit $$anonymous$$t in $$anonymous$$ts)
         {
             if($$anonymous$$t.transform.tag == "Floor")
             {
                 Vector2 uvCoord = $$anonymous$$t.textureCoord;
                 int texelX = Mathf.FloorToInt(uvCoord.x * texW);
                 int texely = Mathf.FloorToInt(uvCoord.y * texH);
                 target = colorGrid[texely*texW + texelX];
             }
         }
         return target; 
     }
 
 }
 

thanx!