Change Mesh face colors / materials at runtime

Question

I'm trying to change the color/material of the faces on my object at runtime. My object has a default SpatialMappingWireframe to begin with:

And I'm trying to assign new colors on start like so:

void Start()
{
    Mesh mesh = GetComponent<MeshFilter>().mesh;

    Color[] colours = new Color[mesh.vertices.Length];

    for (int i = 0; i < mesh.vertices.Length; i++)
    {
        colours[i] = Color.red;
    }

    mesh.colors = colours;

    Debug.Log($"Colour Count: {colours.Length}");
}

I can see the debug line being output, but no changes to my scene:

Apologies if I'm missing something obvious

Answer 1

The default shader on a material does not support assigning new colours. Assigning a new shader to the material asset resolves the issue:

Quoting the a StackOverflow answer:

1. in the Project view (Assets) do right click → Create → Material

   

2. Give that material a name

3. For the Shader from the Dropdown menu find and select e.g. Particles → Standard Unlit (or if you want to receive lightning Standard Surface)

   

4. Finally use this material for your object either by dragging it into the MeshRenderer → material or by simply dragging it onto the according object in the Scene view (the latter might not work if there is no mesh for that object yet)

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Result: