Actually apply all previous SetPixel and SetPixels changes.

If updateMipmaps is true, the mipmap levels are recalculated as well, using the base level as a source. Usually you want to use true in all cases except when you've modified the mip levels yourself using SetPixels. By default updateMipmaps is set to true.

If makeNoLongerReadable is true, texture will be marked as no longer readable and memory will be freed after uploading to GPU. By default makeNoLongerReadable is set to false.

This is a potentially expensive operation, so you'll want to change as many pixels as possible between Apply calls.

The texture has to have Is Readable flag set in the import settings.

	function Start () {
		// Create a new texture and assign it to the renderer's material
		var texture = new Texture2D(128, 128);
		renderer.material.mainTexture = texture;
		// Fill the texture with Sierpinski's fractal pattern!
		for (var y : int = 0; y < texture.height; ++y) {
			for (var x : int = 0; x < texture.width; ++x) {
				var color = (x&y) ? Color.white : Color.gray;
				texture.SetPixel (x, y, color);
			}
		}
		// Apply all SetPixel calls
		texture.Apply();
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Start() {
        Texture2D texture = new Texture2D(128, 128);
        renderer.material.mainTexture = texture;
        int y = 0;
        while (y < texture.height) {
            int x = 0;
            while (x < texture.width) {
                Color color = ((x & y) ? Color.white : Color.gray);
                texture.SetPixel(x, y, color);
                ++x;
            }
            ++y;
        }
        texture.Apply();
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Start() as void:
		texture as Texture2D = Texture2D(128, 128)
		renderer.material.mainTexture = texture
		y as int = 0
		while y < texture.height:
			x as int = 0
			while x < texture.width:
				color as Color = (Color.white if (x & y) else Color.gray)
				texture.SetPixel(x, y, color)
				++x
			++y
		texture.Apply()

See Also: SetPixel, SetPixels functions.