How can I loop through every 3D point on a plane's surface in C#?

Questions & Answers
1

I’m making a model editor for Unity 5 that will allow the developer to draw an image, and then inflate the
image into a 3D object. Of course, it would not inflate transparent points. In order to do this, I’ve created a script that’s connected to a plane with particles/alpha blended enabled in order to ensure the plane shows both sides. I’ve also created a custom editor script that links to the plane’s script. I decided it would be a good idea to disable the mesh renderer when the plane is inflated to ensure people can’t see the deflated object. What I want to do is to loop through each Vector3 on the plane’s surface and create a new object with new points based on the pixels in the object.

So the question is: How can I loop through every 3D point on a plane’s surface in C#?

Bonus points if you can help me find the color of each point, but I think I have that figured out.

UPDATE:

Thanks for all the support! I actually thought of a way to do this that I’m suprised I never thought of.
My idea only works well with planes, but that’s all that I need. I also figured out how to filter colors! You can view the code below.

    public static IEnumerable<Vector3> GetPoints(GameObject obj, float res)
    {
        Vector3[] verts = obj.GetComponent<MeshFilter>().sharedMesh.vertices;
        float x1 = float.MaxValue;
        float x2 = 0;
        float z1 = float.MaxValue;
        float z2 = 0;
        foreach (Vector3 vert in verts)
        {
            if (vert.x < x1)
            {
                x1 = vert.x;
            }
            if (vert.x > x2)
            {
                x2 = vert.x;
            }
            if (vert.z < z1)
            {
                z1 = vert.z;
            }
            if (vert.z > z2)
            {
                z2 = vert.z;
            }
        }
        Vector2 size = new Vector2(Mathf.Abs(x1 - x2), Mathf.Abs(z1 - z2));
        Texture2D tex = ((Texture2D)obj.GetComponent<Renderer>().sharedMaterial.mainTexture);
        for (float x = -(size.x / 2); x <= size.x / 2; x += res)
        {
            for (float z = -(size.y / 2); z <= size.y / 2; z += res)
            {
                Vector3 V3 = obj.transform.TransformPoint(new Vector3(x, 1, z));
                if (tex.GetPixel(tex.width - (int)(((x + (size.x / 2)) / size.x) * tex.width), 
                tex.height - (int)(((z + (size.y / 2)) / size.y) * tex.height)).a > 0.5f)
                yield return V3;
            }
        }
    }

If anyone is wondering how to use the code above, here’s a snipplet (0.1f is the increment):

foreach (Vector3 V3 in GetPoints(gameObject, 0.1f))
{
    GameObject t = Instantiate(gameObject2);
    t.transform.position = V3;
}

Here’s a couple screenshots of what you can do:

74896-plane.png

74901-tree.png

2

You mentioned that you now know how to get each vertex of the MeshFilter’s mesh. These verticies are defined in model-space.
In order to convert these to world-space coordinates use the MeshFilter’s transform.
e.g.

worldVertexPoint=meshfilter.gameobject.transform.TransformPoint(modelVertexPoint);

You could now put an object at that particular worldVertexPoint like so:

someObject.transform.position= worldVertexPoint;

Regarding getting the color of the texture, at that vertex:
Lets go back a step- lets say you got your vertex using

modelVertexPoint= mesh.vertices[vertexNumber];

We can also get the Texture coordinate (UV), of that vertexNumber

Vector2 vertexUV = mesh.uv[vertexNumber];

You can then feed this UV coordinate, into the GetPixel function that MrPMorris mentioned.
The advantage to this method is, it eliminates the need to do any raycasting. It does NOT account for any shadows or lighting though.

note: Colored verticies are optional in a Mesh, and they require a vertex-color-shader to work. Fairly rare nowadays. If you import the mesh it might not have vertex colors defined.
If you ARE using colored verticies , rather than a texture, it’s even simpler:

Color vertexColors= mesh.color[vertexNumber];