Change vertex color of a mesh.

Question

I am trying to color the vertices of a mesh based on each vertex's distance from some nodes. Ultimately I want to use this to color the ground to visually message the player about the fertility of the ground.

I made a test with a cube in the middle and 2 nodes that had different colors associated with them.

         Mesh _mesh; 
     Vector3[] _vertexs; 
 
     public Color _color1;
     public Color _color2; 
     public Transform pos1; 
     public Transform pos2; 
 
     // Use this for initialization
     void ChangeColors(){
         Color[] _color = new Color[_vertexs.Length]; 
         for (int i = 0; i < _vertexs.Length; i++){
             float _distance1 = Distance (_vertexs[i], pos1.position); 
             float _distance2 = Distance (_vertexs[i], pos2.position); 
             float _ratio1 = _distance1 / (_distance1+_distance2); 
             float _ratio2= _distance2 / (_distance1+_distance2);
             _color[i] = _color1 * _ratio1 + _color2*_ratio2; 
         }
         _mesh.colors = _color; 
     }
 
     void Start () {
         _mesh = GetComponent<MeshFilter> ().mesh;  
         _vertexs = _mesh.vertices; 
         ChangeColors (); 
 
 
 
     }
     float Distance(Vector3 _start, Vector3 _end){
         return Vector3.Distance (_start, _end); 
     }
     void ChangeToRed(){
         for (int i = 0; i < _mesh.colors.Length; i++) {
             _mesh.colors[i] = Color.red;         
         }
     }

The interpolation bit works (I used to have it spit out the numbers to the log.) But the colors don't take. If I go through and print out the colors array it's all just white.

I have tried finding shaders that use vertex color but this doesn't seem to be working. (I have no experience with shaders, but I think I may have to learn a bit to solve this problem.)

To reiterate, I'm trying to find a way to assign a color to each vertex of a mesh. Thanks.

Answer 1

Answer by drudiverse · Oct 18, 2014 at 10:01 PM

i think there is a code by c petersen to rewrite the UVS to all the same for each vertex, and make them a function of the distance from point. otherwise, is just sent point informations to the shader and say color values +/- distance from worldspace, say a loop of 10 points that are in view in the map, hopefully less of them.

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Answer 2

Answer by seth_slax · Sep 23, 2015 at 02:43 AM

I'm not sure if this is necessary in C# (I work in JS), but getting the vertex world position, from your code would be:

 float _distance1 = Distance (transform.TransformPoint(_vertexs[i]), pos1.position);

Also for the vertex shader, can't recall where I got this from but this is the simplest one I've found:

  Shader "Vertex Color Lit" {
      Properties {
         _MainTex ("Base (RGB)", 2D) = "white" {}
      }
      SubShader {
         Pass {
             Lighting On
             ColorMaterial AmbientAndDiffuse
             SetTexture [_MainTex] {
                combine texture * primary DOUBLE
             }
         }
      }
  }

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Change vertex color of a mesh.

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