Vertex Tweaker

using UnityEngine;
using System.Collections;

public class VertexTweaker : MonoBehaviour
{
    private Mesh thisMesh;

    private Vector3[] vertexPositionsWorld;
    private Vector3[] vertexNormalsWorld;

    private float distanceToChanger = 100f;
    private Color[] colours;
    private float vertexCount = 0;

    public void ClearVertexColours()
    {
        if (thisMesh == null)
            thisMesh = GetComponent<MeshFilter>().mesh;
        colours = new Color[thisMesh.vertexCount];

        for (int j = 0; j < thisMesh.vertexCount; j++)
        {
            colours[j] = Color.black;
            //colours[j].a = 0f; // you can do this, but I've just tweaked the shader so A is inverted, A == 1 is no blood
        }
        thisMesh.colors = colours;
    }
    void Awake()
    {
        thisMesh = GetComponent<MeshFilter>().mesh;
        colours = new Color[thisMesh.vertexCount];

        ClearVertexColours();
        vertexPositionsWorld = new Vector3[thisMesh.vertexCount];
        vertexNormalsWorld = new Vector3[thisMesh.vertexCount];
        for (int j = 0; j < thisMesh.vertexCount; j++)
        {
            vertexPositionsWorld[j] = transform.TransformPoint(thisMesh.vertices[j]);
            //vertexNormalsWorld[j] = transform.TransformDirection(thisMesh.normals[j]);

        }
        vertexNormalsWorld = thisMesh.normals;
        vertexCount = thisMesh.vertexCount;
    }


    public void ChangeInArea(Color color, Vector3 position, float radius, float strength)
    {
        colours = thisMesh.colors;
        for (int j = 0; j < vertexCount; j++)
        {
            distanceToChanger = (vertexPositionsWorld[j] - position).magnitude;
            if (distanceToChanger < radius)
            {
                colours[j].r = color.r;
                colours[j].g = color.g;
                colours[j].b = color.b;

                colours[j].a -= strength;
                colours[j].a = Mathf.Clamp01(colours[j].a);

            }


        }

        thisMesh.colors = colours;
    }
    public void ChangeInArea(Color color, Vector3 position, float radius, float strength, Vector3 direction)
    {
        colours = thisMesh.colors;
        direction = direction.normalized;
        float facingDot = 0;
        for (int j = 0; j < vertexCount; j++) //iterate through each vertex
        {
            distanceToChanger = (vertexPositionsWorld[j]- position).sqrMagnitude;
            facingDot = Vector3.Dot(direction, vertexNormalsWorld[j]);
            if (distanceToChanger < radius)
            {
                if (facingDot < 0.5f)
                {

                    colours[j].r = color.r;
                    colours[j].g = color.g;
                    colours[j].b = color.b;

                    colours[j].a -= strength;
                    colours[j].a = Mathf.Clamp01(colours[j].a);
                    //uv3s[j].x += strength;
                    //uv3s[j].x = Mathf.Clamp01(uv3s[j].x);
                }
            }


        }
        thisMesh.colors = colours; //apply the new colours
    }


}