1

Hi! I have a problem with assigning color information from an image to a grid of primitives. I want to rebuild the image with primitives to use the third dimension for storing information. It will be for data vis purposes.

// Error-Log: NullReferenceException: Object reference not set to an instance of an object
DrawPrimitives.Start () (at Assets/nuilab/Scripts/DrawPrimitives.cs:13)

I am relatively new to Unity, C# and coding in general. I handled NullReferenceExeptions by myself until now. I do not find the problem. I hope that someone can lend me his or her eyes to track the issue.

Here is the first script which grabs the color information:

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class GetTextureColors: MonoBehaviour
{
    public Texture2D Tex;
    public int skip = 10;

    Color[] AllColors;

    //-------------------------------------------------------------------
    void Start()
    {
        List<Color> ListOfColors = new List<Color>();

        for (int x = 0; x < Tex.width; x += skip)
        {
            for (int z = 0; z < Tex.height; z++)
            {
                int currentPixel = x + z * Tex.width;
                Color currentColor = Tex.GetPixel(x, z);
                ListOfColors.Add(currentColor);
            }
        }
        AllColors = ListOfColors.ToArray();
    }

    //-------------------------------------------------------------------
    public Color[] GetColors()
    {
        return AllColors;
    }
}

Here is the second script that builds all primitives:

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class DrawPrimitives: MonoBehaviour {

    GetTextureColors GetTextureColorsScript;
    Texture2D Texture;
    Color[] currentColor;
    //-------------------------------------------------------------------
	void Start()
	{
        currentColor = GetTextureColorsScript.GetColors();
        GetTextureColorsScript = GetComponent<ChangeTexture>();
        Texture = GetTextureColorsScript.Tex;

        GeneratePrimitives();
    }

	//-------------------------------------------------------------------
	void GeneratePrimitives()
	{
        int skip = ChangeTextureScript.skip;
        for (int x = 0; x < Texture.width; x += skip)
        {
            for (int z = 0; z < Texture.height; z += skip)
            {
                int currentPixel = x + z * Texture.width;

                Vector3 vertex = new Vector3(x * 0.1f, 0, z * 0.1f);

                GameObject Point = GameObject.CreatePrimitive(PrimitiveType.Cube);
                Point.transform.position = vertex;
                Point.transform.localScale = new Vector3(0.5f, 0.5f, 0.5f);

                Renderer rend = GetComponent<Renderer>();
                rend.sharedMaterial.shader = Shader.Find("Cube_Material");
                rend.sharedMaterial.SetColor("_Color" + currentPixel.ToString(), currentColor[currentPixel]);  
            }
        }
	}
}
2

Did you attach GetTextureColors script to the same object that uses your method? Because if you didn’t, your variant GetTextureColorsScript is null.

3

I found the problem. I was accessing the render component of the current gameObject instead of the instance gameObjects.

Old code:

Renderer rend = GetComponent<Renderer>();
rend.sharedMaterial.SetColor("_Color" + currentPixel.ToString(), currentColor[currentPixel]);

New code:

Renderer rend = Point.GetComponent<Renderer>();
rend.material.color = currentColor[currentPixel];